Aircrete Blocks Technical Manual

aircrete blockstechnical manual

aircre

teblo

cks

technicalmanual

Customer Services:

T 08705 626500 F 08705 626550E [email protected] www.hanson.biz/uk

Hanson Building ProductsHead OfficeStewartbyBedfordMK43 9LZ

Aircrete Blocks CI/SfB

February 2007Ff4

Uniclass L3221: P2

464.5 Thermalite binder_2:464.5 Thermalite binder_2 7/3/07 13:23

1

ContentsIntroduction 2-3

Sustainability and the environment 4-8

1. Product data

Product summary 10-11

Product data 12-22

2. Thin joint masonry 24-31

3. Performance

Thermal insulation 34-41

Air permeability 42

Fire protection 43

Sound insulation 44-49

Moisture penetration 50-51

Frost resistance 52

4. Design detailing

Foundations 54-55

Floors 56

External walls 57-60

Partitions 61-62

Separating walls 63

Reveals 64

Movement control 65-68

Structural use 69-70

5. Sitework

CDM Regulations 72-73

Health and Safety 74-75

Mortar 76-77

Workability 78

Fixings 79-81

Internal finishes 82-83

External finishes 84-86

6. Other information

Sales and technical advice 88-89

Quality 90

464.4 Thermalite manual V8 b:464.4 Thermalite manual V8 b 7/3/07 14:07 Page 1

Thermalite introduced the autoclavedaerated concrete block over 50 yearsago, and now produces the best sellingrange of building blocks in the UnitedKingdom.?????

Thermalite aircrete blocks

2

Continual research and development have resulted in a range of building blocks that meets the demands of the modern construction industry. Consequently, the Thermalite range of aerated concrete blocks offers both builders and specifiers a wealth of benefits unrivalled by any other concrete block manufacturer.

Thermalite blocks are not only easy to handle, they are extremely workable and can be easily cut, sawn andchased accurately with ordinary hand tools.

Up to 80% of the raw material used in the manufacture of Thermalite is pulverised fuel ash (PFA), a stable ‘by-product’ of coal-burning power stations. This recycled material is mixed with sand, cement, lime, aluminium powder, together with processed waste and water, to produce a range of blocks noted for their high thermal insulation.

IntroductionThe Thermalite brand of aircrete blocksfrom Hanson offers cost effectivesolutions for a wide range ofapplications. The micro-cellular structureof Thermalite, featuring millions of tinypockets of trapped air, gives this productits distinctive features: high compressivestrength, lightness for handling, highthermal insulation and moistureresistance.


3

QualityAll Thermalite products are manufactured to a qualityassured system, in accordance with EN ISO 9001 andBS EN 771-4, ensuring compliance with all relevantstandards and codes of practice. In addition, Thermaliteproducts have independent accreditation from theBritish Board of Agrément.

All manufacturing locations hold a Kitemark license andhave dedicated laboratories where testing is routinelyconducted. Hanson also has a UKAS accreditedlaboratory (see also page 90).

Sustainability and the environment Thermalite is the most environmentally friendly aircreteproduct available in the United Kingdom. All manufacturing locations are certified by both theenvironmental standards BS EN ISO 14001 and theBuilding Research Establishment (BRE).

See pages 4-7 for further information on Thermalite’senvironmental credentials.

Construction (Design and Management)Regulations The Thermalite micro-cellular structure results in aproduct range that is both strong and exceptionally lightto handle. Indeed, standard size blocks are available inweights less than 20kg, in accordance with guidelines.The Health & Safety Executive also recommends thatblocks with handholds should be selected whereverpossible. Thermalite is the first aircrete product in theUnited Kingdom to offer handholds, which have beenintroduced in the Trenchblock range, to further aid theprocess of lifting and laying foundations, makingbuilding with Thermalite not only faster, but safer too.

See also CDM Regulations, page 72.

Thin joint masonryThin joint masonry is a system of construction that isdesigned to lower costs by speeding up the time takento build walls and is recognised as a Modern Method ofConstruction (MMC). By using Thermalite Thin LayerMortar and aircrete blocks, the depth of mortar can bereduced from at least 10mm to 3mm or less.

00/372091/2723

ENP168

0640

The lightweight nature of Thermalite and the rapidsetting time of thin layer mortar, means that acontinuous build is possible, which in turn createssubstantial productivity gains.

Thermalite Thin Layer Mortar is a pre-mixed, cement-based product that only requires adding to water tomake an easily applied mortar. It provides an alternativeto general purpose sand/cement mortar.

The nature of Thermalite blocks and the strict controlover the manufacturing process ensures that the blocksare produced to a high degree of dimensional accuracy,making them ideal for use with thin layer mortar.

The increasing demands of the UK constructionindustry for higher build quality, greater productivity,improved thermal performance, airtightness and wastereduction mean that the benefits offered by thin jointmasonry are becoming increasingly more relevant.

For further information, see page 24, ‘Thin JointMasonry’.

Large format productsThermalite Large Format blocks are available in twoface sizes, the equivalent of at least two normal formatblocks and have been specifically designed to offersignificant gains in productivity.

Independent tests have indicated that the use of LargeFormat blocks can result in time savings of 50%compared with laying normal concrete blocks. Typically, Thermalite Large Format blocks also weighless than 20kg, thus ensuring compliance with the CDM Regulations.

ServicesHanson continually researches the needs of customersin order to develop the range of products available.Additionally, a comprehensive range of literature isavailable along with technical advice on all aspects ofthe application and use of Thermalite products inconstruction.

See Sales and Technical Advice page 88.


4

SustainabilityThe manufacturing process of Hanson’s Thermaliterange of products and services is designed to promotesustainability, both before and after the product leavesthe factory gate.

To be environmentally sustainable, a product needs tobe manufactured and used in such a way as to minimiseits impact on the environment. This is a key issueconfronting the construction industry and commandsconstruction solutions that minimise the consumptionand use of natural resources. At Hanson, we recognisethe impact that we can have on the environment, so wemanage all activities to maximise our contributiontowards the protection of the environment and thepreservation of natural resources.

Reduction, re-use and recyclingThe Thermalite range of aircrete blocks is made from upto 80% recycled materials. Reduction, re-use andrecycling are the only really green solutions to theenvironmental impact of waste and wherever possible,recycled materials are used in the manufacture ofHanson’s products, thereby reducing the use of primaryaggregates.

Sustainability and theenvironmentHanson continues to ensure that itsThermalite products are at the forefrontwhen meeting key sustainability andenvironmental requirements for both newbuild and extensions, making Thermalitethe greenest choice for your project.

Pulverised fuel ashUp to 80% of the material used in Hanson’s Thermaliteblocks is pulverised fuel ash (PFA), a by-product fromcoal burning power stations, which is both stable andenvironmentally friendly.

Waste minimisationA strict waste minimisation scheme is operated duringmanufacture and all waste from the process is eithercrushed and recycled into the next mix, used in otherconcrete products or as an aggregate bulk fillreplacement in road construction.

Energy savingThe micro-cellular structure of the Thermalite productoffers remarkably high thermal insulation and,consequently, lowers energy consumption for theheating of buildings. The finished product alsocontributes to waste reduction – Thermalite blocks aremade to high dimensional tolerances and can be easilyand accurately cut to reduce waste on site.


5

Contributing to energy efficiencyHanson also operates a modern transport fleet, which,when combined with the lightweight Thermalite product,ensures that energy consumption during haulage isminimised.

No pollutionThe Thermalite product provides no direct pollution risk to water or air and the stable and inert wastematerials can be safely used as land infill whererecycling is not feasible.

Ecopoints RatingThermalite is the first block in the UK to receive aCertified Environmental Profile and Ecopoint score fromthe Building Research Establishment (BRE).

When used in an external wall, Thermalite products achieve an “A” rating in the Green Guide to Specification.

EcopointsTo improve the usefulness of the environmental dataand make it easier to understand, BRE has developedEcopoints – a method of ranking and scoring differentenvironmental impacts. Ecopoints allow a wide range ofenvironmental impacts (e.g. energy use and mineralextraction) to be compared using the same measure.The lower the Ecopoints score, the lower theenvironmental impact. As a benchmark, it has beendetermined that 100 Ecopoints are equal to the impactof one UK citizen on the environment for one year. A tonne of Thermalite equates to just 1.9 Ecopoints.

‘ The potential savings from reducing consumption and increasing the re-use and recycling of materials are ona scale which could contribute significantly to national objectives on sustainable development.’Department of Transport, Local Government and the Regions.

Life Cycle AssessmentThermalite was the first aircrete block to have its LifeCycle Assessment (LCA) data independently reviewedand to be awarded Certified Environmental profiles byBRE Certification. For many years, the BuildingResearch Establishment (BRE), through its Centre forSustainable Construction, has been encouraging theuse of Life Cycle Assessment (LCA), to allow architects,builders and clients to make informed environmentalcomparisons between construction products. LCA is amethod that measures the environmental impact of aproduct by assessing the energy and materials usedand released to the environment over its full life cycle.LCA results are presented in the form of anEnvironmental Profile.


6

Sustainability and the environment

Thermalite – analysis of a square metre of wallelement over a 60 year life (measured in Ecopoints)

Brick

Thermalite

Mortar for brick

Rockwool rollbatt insulation

Mortar for block

Plasterboard

Transport

Putting Ecopoints in contextAt its simplest level, the profiling method can assess theimpact of a single building product, such as blocks.However, to make valid comparisons, designers needinformation about a building element, such as a wall.A building element is likely to be made up of severalproducts (such as bricks, blocks and mortar), soEnvironmental Profiles take this into account by addingtogether the contribution of the component parts,allowing comparison between one construction elementand another.

The BRE’s Certified Environmental Profiles enablemanufacturers to demonstrate the credibility of theirproducts. They also help designers and specifiersidentify materials that will best fulfil a sustainable brief.

The pie chart opposite illustrates the relativesignificance of various components of a wall. The chartshows that Thermalite blocks contribute less than 20%of the total environmental impact of a wall construction.

CertificationThermalite was the first aircrete product to be awardedthe coveted environmental manufacturing standard, BS EN ISO 14001, for its manufacturing locations.Thermalite is also the first block in the UK to receive aCertified Environmental Profile and Ecopoint score fromBRE. The Ecopoint score translates into a ‘Green Guide’rating of ‘A’ (when used within an external wall element).This can be used to obtain credits in BREEAM andEcoHomes.

‘The use of aerated blocks, which are lightweight and provide insulation, improves environmental performance.’The Green Guide to Specification


7

Green Guide wall elements Ecopoints /m2 Ecopointsrating

1 square metre over 60 year life: external wall: cavity wall construction:brickwork, 65mm rock wool cavity wall insulation, 100mm ThermaliteTurbo blockwork, plasterboard internal face. 0.98 A

1 square metre over 60 year life: external wall: cavity wall construction:brickwork, 65mm rock wool cavity wall insulation, 115mm ThermaliteTurbo blockwork, plasterboard internal face. 1.0 A

1 square metre over 60 year life: external wall: solid wall construction:rendered, 365mm Thermalite Turbo blockwork, plasterboard internal face. 0.98 A

1 square metre over 60 year life: external wall: cavity wall construction:brickwork, 65mm rock wool cavity wall insulation, 100mm ThermaliteShield blockwork, plasterboard internal face. 1.0 A

1 square metre over 60 year life: external wall: cavity wall construction:brickwork, 75mm rock wool cavity wall insulation, 100mm ThermaliteShield blockwork, plasterboard internal face. 1.0 A

1 square metre over 60 year life: internal wall: cavity wall construction:12.5mm plasterboard on dabs, 7mm nominal parge cement-based render,100mm Thermalite Shield, 75mm clear cavity, 100mm ThermaliteShield, 7mm nominal parge cement-based render & 12.5mmplasterboard on dabs 0.66 A

1 square metre over 60 year life: external wall: cavity wall construction:brickwork, 75mm rock wool cavity wall insulation, 100mm ThermaliteHi-Strength 7 blockwork, plasterboard internal face. 1.1 A

The Green Guide to SpecificationThe ‘Green Guide to Specification’ contains tablesshowing the summary ratings, measured in Ecopointsper m2 for all of the elements included in the GreenGuide. The information below shows the Green Guideratings for external walls, where Thermalite productsreceive an ‘A’ rating.

Applying the Green Guide to SpecificationWhilst all specification choices are important, designersmay wish to pay particular attention to the selection ofbuilding elements that have the potential for the leastenvironmental impact.


8

Sustainability and the environment

Environmental policy

‘One North East’ achieved an ‘Excellent’ rating under BREEAM for Offices 2002

Managing environmental issues is an integral part of Hanson’s business strategy. We endeavour to achievea high standard of environmental performance and to make a positive contribution to society through ourproducts and land management programmes. Our policy is to:

• Comply with environmental legislation, regulations and other codes of practice adopted by the company(such as industry initiatives) and plan ahead for future requirements

• Monitor, evaluate and continuously improve environmental performance through the adoption of environmentalmanagement systems

• Respond to the needs and concerns of local communities

• Strive towards sustainability, balancing today’s needs with those of the future

• Improve employee awareness of environmental issues and encourage the sharing of experience and expertisewithin our business

• Minimise adverse environmental impacts of the company’s activities

• Conserve resources and minimise the generation of waste

• Make appropriate resources and training available to implement the policy


9

1 Product dataProduct summary table 10

Turbo 12

Shield 13

Hi-Strength 7 14

Hi-Strength 10 15

Paint Grade Smooth 16

Hi-Strength Paint Grade Smooth 17

Party Wall 18

Floorblock 19

Trenchblock/Tongue & Groove 20

Hi-Strength Trenchblock/Tongue & Groove 21

Coursing Brick 22


10

Product summary

Product Available block Availablewidths (mm) face dimensions (mm)

Turbo 100 115 125 130 140 150 440 x 215 440 x 430190 200 215 265 300

Shield 75 90 100 125 140 150 440 x 215 440 x 140190 200 440 x 430 440 x 540(4)

Hi-Strength 7 100 140 150 190 200 215 440 x 215 440 x 430

Hi-Strength 10 100 140 150(3) 190(3) 200(3) 215(3) 440 x 215

Paint Grade Smooth 100 140 150 190 200 215 440 x 215 440 x 430

Hi-Strength Paint Grade 100 140 150 190 200 215 440 x 215 440 x 430Smooth

Party Wall 100 215 440 x 215 440 x 430

Floorblock 100 440 x 350 440 x 215 540 x 440

Floor Endblock 150 175 440 x 140

Coursing Slip 40 65 215 x 100 (Plan dimensions)

Trenchblock / 255 275 300 330(3) 355(3) 440 x 215 440 x 140(5)

Tongue & Groove

Hi-Strength Trenchblock / 255 275 300 330(3) 355(3) 440 x 215 440 x 140(5)

Tongue & Groove(7.3N/mm2 shown)

Coursing Brick 100 115 125 130 140 150 215 x 65

Notes (1) BRE Special Digest 1: Concrete in aggressive ground (2) May be used in situations described in A1, A2, but not in situations described in A3 of Table 13 of BS 5628: Part 3

(3) Manufactured to special order only (4) Compressive strength 3N/mm2, manufactured to special order only (5) Not available with Tongue and Groove jointing (6) See notes on page 22

Key � = recommended use Note Thermalite products have a typical mean moisture movement value of 0.4mm/m


11

Compressive Designed thermal Nominal Soil or External Cavity Separating Belowstrength (N/mm2) conductivity λ density groundwater wall solid inner leaf (party) wall dpc levelto: BS EN 771-4 (W/m.K) (kg/m3) D.S. class(1)

2.9 0.11 470 1, 2, 3 �(7) – – �(2)

3.6 0.15 600 1, 2, 3, 4 � � � �

7.3 0.19 730 1, 2, 3, 4 � � � �

8.7(8) 0.20 770 1, 2, 3, 4 � � � �

4.0 0.16 660 – – � – –

7.3 0.19 730 – – � � –

4.0 0.16 660 1, 2, 3, 4 � � � �

4.0 0.16 660 – – – – –

3.6 0.15 600 1, 2, 3, 4 – – – �

7.3 0.19 730 1, 2, 3, 4 – – – �8.7(8) 0.20 770 1, 2, 3, 4 – – – �

(6) n/a n/a – – � � –

This summary is representative of the standard product range. Other sizes may be available to special order. Please contact

Customer Services (see pages 88-89) for further details.

(7) Where an external leaf is constructed using Turbo blocks of widths less than 215mm thick, a traditional sand/cement render should not be applied. This is to minimise the risk of failure caused by the

differences in tensile strength between the finish and background material. If a ‘technical’ render system solution is proposed, the advice of the render system manufacturer should be sought.

(8) 10.4N/mm2 equivalent. Blocks are manufactured to BS EN 771-4, Category 1 which allows the use of an enhanced partial safety factor (BS 5628). Manufactured to special order only. 10.4N/mm2

equivalent Trenchblock is not available with Tongue and Groove jointing.


12

Product data

Turbo

Widths and weights

Block weights at equilibrium density(for 440 x 215mm face dimension)

block width(mm) 100 115 125 130 140 150 190 200 215 265 300**

block weight†

(kg) 4.6 5.3 5.7 6.0 6.4 6.9 8.7 9.2 9.9 12.1 13.7

wall weight‡

(kg/m2) 57 66 72 75 80 86 109 115 123 152 172

**Manufactured to special order only† Block weights are calculated using specified gross dry density,with a moisture content of 3% by weight added to provide theequilibrium value.

‡ Weight of erected wall (including mortar). Add 11kg/m2 per sidefor a 2-coat lightweight plaster finish (24kg/m2 for dense plaster).

external walls • foundations • partitions

Strength 2.9N/mm2

Thermal conductivity 0.11W/m.K

Density 470kg/m3

Turbo offers very high thermal insulation properties andis therefore ideal for external solid wall applications(min. block thickness 215mm) where low U-Values are required.

• Available in large format• For use with Thermalite Thin Layer Mortar• Use only in soils up to Design Sulfate Class DS 3*

below ground

Working dimensionsFace dimensions (mm) 440 x 215, 440 x 430

Tolerances • For general purpose mortar:

Length: + 3mm, - 5mmWidth: ± 2mm Height: + 3mm, - 5mm

• For thin layer mortar: Length: ± 3mm Width: ± 2mm Height: ± 1.5mm

PropertiesMean compressive strength not less than 2.9N/mm2

Designed thermal conductivity (λ) 0.11W/m.K

Specified gross dry density 470kg/m3

* May be used in situations described in A1, A2 but not in situationsdescribed in A3 of Table 13 of BS 5628: Part 3.


13

Shield

Widths and weights


block width(mm) 75 90 100 125 140 150 190 200

block weight†

(kg) 4.4 5.3 5.8 7.3 8.2 8.8 11.1 11.7

wall weight‡

(kg/m2) 52 63 70 87 98 105 133 140

† Block weights are calculated using specified gross dry density,with a moisture content of 3% by weight added to provide theequilibrium value.


external walls • foundations • partitions • separating walls

Strength 3.6N/mm2


Density 600kg/m3

Shield combines all the normal qualities of Thermaliteblocks with extremely high moisture resistance.

• Available in large format• For use with Thermalite Thin Layer Mortar

Working dimensionsFace dimensions (mm) 440 x 215, 440 x 140, 440 x 430, 540 x 440†







†Only available in 100mm thickness with a compressive strength of3N/mm2, manufactured to special order only.


14

Product data

Hi-Strength 7

Widths and weights


block width(mm) 100 140 150 190 200 215

block weight†

(kg) 7.1 10.0 10.7 13.5 14.2 15.3

wall weight‡

(kg/m2) 82 115 124 157 165 177




Strength 7.3N/mm2


Density 730kg/m3

Hi-Strength 7 has been specifically designed forapplications such as flats of three storeys and above,offices, supermarkets and retail parks, where loadingconditions require a 7.3N/mm2 building block.

• Available in large format• For use with Thermalite Thin Layer Mortar









15

Hi-Strength 10

Widths and weights


block width(mm) 100 140 150** 190** 200** 215**

block weight†

(kg) 7.5 10.5 11.3 14.3 15.0 16.1

wall weight‡

(kg/m2) 86 121 129 164 173 186



*Blocks are manufactured to BS EN 771-4, Category 1, whichallows the use of an enhanced partial safety factor (BS 5268). This provides the equivalent of a 10.4N/mm2 compressive strength.

**Manufactured to special order only.


Strength 8.7N/mm2 (10.4N/mm2 equivalent)*


Density 770kg/m3

Hi-Strength 10 has been specifically developed forstructural applications such as three or four storeybuildings, where loading conditions require a10.4N/mm2 building block.

Hi-Strength 10 blocks are available in a range of widthsas a special order item only. Please contact our ProductServices department for full details.





PropertiesMean compressive strength not less than 8.7N/mm2*




16

Product data

• Average saturated compressive strength: not less than 4.0N/mm2

• Designed thermal conductivity (λ): 0.16W/m.K

• Specified gross dry density: 660kg/m3

Widths and weights


block widths(mm) 100 140 150 190 200 215

block weight†

(kg) 6.4 9.0 9.6 12.2 12.9 13.8

wall weight‡

(kg/m2) 76 106 114 144 151 163


‡ Weight of erected wall (including mortar).




* Block weights are calculated using specified dry density, with a moisture content of 3% by weight added to provide theequilibrium value.

Paint Grade Smoothinner leaves of external walls • partitions

Strength 4.0N/mm2


Density 660kg/m3

Paint Grade Smooth is a paint grade block with theclean lines, even surfaces and neat sharp arrises thatsmooth faced walling demands. It is available for use ina variety of building projects such as leisure centres,retail buildings, offices and schools.

Note: If required, Paint Grade Smooth can also be laid fair faced.However, consideration should be given to the fact that colourvariation can occur.

It is recommended that a Paint Grade Smooth sample panel iserected for comparison purposes before construction commencesand that selection is undertaken during construction. It may also benecessary to fill small blow holes before decoration.

Due to width variations within manufacturing tolerances, it may bedifficult to build solid partition walls which have a smooth and evensurface on both sides.

Working dimensionsFace dimensions (mm) 440 x 215





17

Hi-Strength PaintGrade Smoothinner leaves of external walls • partitions

Strength 7.3N/mm2


Density 730kg/m3

Widths and weights


block width(mm) 100 140 150 190 200 215

block weight†

(kg) 7.1 10.0 10.7 13.5 14.2 15.3

wall weight‡

(kg/m2) 82 115 124 157 165 177

†Block weights are calculated using specified gross dry density, witha moisture content of 3% by weight added to provide theequilibrium value.

‡ Weight of erected wall (including mortar).




Hi-Strength Paint Grade Smooth combines the highquality appearance of Paint Grade Smooth with thecompressive strength of Thermalite Hi-Strength blocks.

It is recommended that a Hi-Strength Paint Grade Smooth samplepanel is erected for comparison purposes before constructioncommences and that selection is undertaken during construction. It may also be necessary to fill small blow holes before decoration.Due to width variations within manufacturing tolerances, it may bedifficult to build solid partition walls which have a smooth and evensurface on both sides.

Working dimensionsFace dimensions (mm) 440 x 215





Widths and weights


block width(mm) 100 215

block weight†

(kg) 6.4 13.8

wall weight‡

(kg/m2) 76 163



18

Product data

Party Wallseparating walls • partitions • external walls • foundations

Strength 4.0N/mm2


Density 660kg/m3

Party Wall is a lightweight concrete block that giveshigh levels of sound reduction in separating wallsbetween buildings.

• Suitable for both cavity and solid wall constructions• Available in large format• For use with Thermalite Thin Layer Mortar

Working dimensionsFace dimensions (mm) 440 x 215, 440 x 430*







* Manufactured to special order only


19

Floorblockbeam and block floors

Strength 4.0N/mm2‡


Density 660kg/m3

Widths and weights

Floorblockface dimensions (mm) 440 x 350 440 x 215 540 x 440*block width (mm) 100 100 100block weight† (kg) 10.5 6.4 16.2

Floor Endblockface dimensions (mm) 440 x 140block width (mm) 150, 175block weight† (kg) 6.0, 7.0

Coursing Slipsface dimensions (mm) 215 x 100block width (mm) 40, 65

* Blocks can be laid to correspond with 540mm beam spacing(660kg/m3 density only)





Floorblock is an efficient method of providing insulatedfloors. It is light in weight and is designed for use withall proprietary T-beams and can improve thermalperformance of the floor.

Detailing is made simple by the availability of specialFloor Endblocks and Coursing Slips in two modularbedding heights for closing at the edge of the floor.

Note: After the Floorblocks have been positioned, before anytrafficking or loading is allowed and before any floor finish iscommenced, the floor must be grouted with a 1:4 cement/sharpsand composition.

‡ 7.3N/mm2 also available on request, subject to manufacturer’sassessment.


20

Product data

Trenchblock/Tongue& Groovefoundations

Strength 3.6N/mm2


Density 600kg/m3

Thermalite Trenchblock is a tried and tested, economicalalternative to the construction of cavity walls withconcrete infill for foundations.

• For use in soils of up to Design Sulfate Class DS 4• Available with tongue and groove joints and handholds• Improves thermal performance• Eliminates need to mortar perpends

Dimensions• Face dimensions (mm): 440 x 215, 440 x 140*

*Not available with tongue and groove joints




Properties• Mean compressive strength:

not less than 3.6N/mm2

• Designed thermal conductivity (λ): 0.15W/m.K (above ground), 0.24W/m.K (below ground)

• Specified gross dry density: 600kg/m3

Widths and weights

Block weights at equilibrium density

face dimensions (mm) 440 x 215 440 x 140

block width (mm) 255 275 300 330‡ 355‡ 255 275 300 330‡ 355‡

block weight†

(kg) 14.9 16.1 17.5 20.8 21.3 9.7 10.5 11.4 12.6 13.5

wall weight (kg/m2) 178 192 210 231 248 185 200 218 240 258


‡ Manufactured to special order only.


21

Hi-Strength Trenchblock/Tongue & Groovefoundations

Strength 7.3, 8.7N/mm2 (10.4N/mm2 equivalent)*


Density 730kg/m3

Thermalite Hi-Strength Trenchblock provides all thebenefits of Trenchblock, together with the 7.3N/mm2

compressive strength of Thermalite Hi-Strength.

• For use in soils of up to Design Sulfate Class DS 4

• Available with tongue and groove joints and handholds

Dimensions• Face dimensions (mm): 440 x 215, 440 x 140**




Properties• Mean compressive strength:

not less than 7.3, 8.7N/mm2

• Designed thermal conductivity (λ): 7.3N/mm2 0.19W/m.K (above ground), 7.3N/mm2 0.31W/m.K (below ground)8.7N/mm2 - 0.20W/m.K (above ground)8.7N/mm2 - 0.32W/m.K (below ground)

• Specified gross dry density: 7.3N/mm2 - 730kg/m3

8.7N/mm2 - 770kg/m3

Widths and weights

Block weights at equilibrium density

face dimensions (mm) 440 x 215 440 x 140

block width (mm) 255 275 300 330‡ 355‡ 255 275 300 330‡ 355‡

block weight† (kg)7.3N/mm2 18.1 19.6 21.3 23.5 25.3 11.8 12.7 13.9 15.3 16.48.7N/mm2 19.1 20.6 22.5 24.8 26.6 12.5 13.4 14.7 16.1 17.3

wall weight (kg/m2)7.3N/mm2 210 227 247 272 293 216 233 255 280 3018.7N/mm2 220 237 259 285 306 226 244 266 292 315


‡ Manufactured to special order only.

*Blocks are manufactured to BS EN 771-4, category 1 which allows the use of an enhanced partial safety factor (BS 5268). This provides the equivalent of a 10.4N/mm2 compressive strength.Manufactured to special order only. Not available with Tongue andGroove jointing.

**Not available with Tongue and Groove joints.

Hi-Strength 7

Hi-Strength 10


22

Product data

Coursing Brickbonding • coursing • infill • making-up

Strength 2.9, 7.3*, 8.7*N/mm2 (10.4 N/mm2 equivalent)†

Coursing Bricks are aerated blocks produced instandard brick sizes for use in bonding and infill toensure that a uniform thermal performance is achievedthroughout the wall.

• Protect against pattern staining• Infill above doors and windows• Coursing at floor and ceiling level• Making up between joists• Hi-Strength Coursing Bricks are also available for use

in walls built of Hi-Strength 7 and Hi-Strength 10blocks

Working dimensions• Face dimensions (mm) 215 x 65

NotesThermalite Coursing Bricks are suitable for use externally andinternally, above or below dpc level in loadbearing or non-loadbearing applications.

Loadbearing walls should not be constructed with ThermaliteCoursing Bricks as the sole masonry unit.

Additionally, standard Coursing Bricks should not be used in wallswhere the compressive strength requirement for the blockwork is inexcess of 2.9N/mm2.

Widths

face dimensions(mm) 215 x 65

block width (mm) 100 115 125 130 140 150

*Manufactured to special order only. Please allow a minimum of 10working days for availablity.

† Blocks are manufactured to BS EN 771-4, Category 1 whichallows the use of an enhanced partial safety factor. This providesthe equivalent of 10.4N/mm2 compressive strength. Manufacturedto special order only.


23

2 Thin joint masonryThin joint masonry 24

Products 26

The Thermalite House 27

Speed trial report 28

Installation 29


24

Thin joint masonryThermalite Thin Joint Masonry is a fast, clean and accurate system ofconstruction, designed to lower costs by reducing the time taken to buildwalls. An accepted ‘Modern Method of Construction’ (MMC), the thin jointsystem can achieve improvements on many different build programs andwhen used with aircrete blocks, the depth of mortar can be reduced from10mm to 3mm, or less.

IntroductionThermalite Thin Joint Masonry is a fast, clean andaccurate construction system using Thermalite blocksmanufactured to a high degree of dimensional accuracyand a thin layer of mortar.

Thin joint masonry is accepted as a ‘Modern Method ofConstruction’ that can achieve improvements on manydifferent build programs.

Trials were first conducted on thin joint construction inthe 1980s, but there is a far longer history of its use inContinental Europe. The increasing demands of the UKconstruction industry for higher build quality, greaterproductivity, improved thermal performance, airtightnessand waste reduction, mean that the benefits offered bythin layer mortar are becoming increasingly relevant.

Thin layer mortarThermalite Thin Layer Mortar is a pre-mixed, cement-based product that only needs adding to water to makean easily-applied mortar. It differs from general purposemortar in that it sets far more rapidly, thus giving earlystability to the construction.

It provides an alternative to general purposesand/cement mortar and allows the depth of the mortarto be reduced from at least 10mm to 3mm or less.

Thin joint masonryThe benefits offered by Thermalite Thin Layer Mortarare provided by a system which retains many of thecharacteristics of traditional blockwork construction. This means that familiarity with the build process andflexibility are inherent in the system.

The nature of Thermalite blocks and strict control of the manufacturing process ensures that the blocks areproduced to a high degree of dimensional accuracy (± 1.5mm on bed height) making them ideal for usewith Thermalite Thin Layer Mortar.

BenefitsNearly all of the blocks in the Thermalite range can beproduced with the required tolerances for use in wallsconstructed using Thermalite Thin Layer Mortar. Thisallows both designers and builders to benefit from thefull range of opportunities offered by this construction.

Faster build speed

The application of Thermalite Thin Layer Mortar toThermalite blocks is achieved by the use of a serratedscoop applicator, which allows mortar to be quickly andaccurately applied to the bed joint of the wall. The fullbenefits can be realised on long runs of walling.

Independent speed trials, conducted by a leadingChartered Building Surveyor, have indicated that a wallof Thermalite blocks and Thermalite Thin Layer Mortarcan be laid twice as fast as that built with aggregateblocks and general purpose mortar (see Speed TrialReport, page 28).

This speed of construction can be further enhancedwhen using Thermalite Large Format blocks, which havea face size equivalent to two traditional concrete blocks.

‘Overall, the use of Thermalite blocks in a thin joint construction can improve build quality and offers time and cost savings for the builder.’


25

Increased productivity

Thermalite Thin Layer Mortar is different from generalpurpose mortar in that it sets far more rapidly. The samehigh levels of productivity are not achievable withmasonry built using general purpose mortar, whichrequires more time to attain sufficient strength tosupport further construction, thus limiting the height thatcan be built in one day.

Typically, Thermalite blocks built with Thermalite ThinLayer Mortar will be stable after 60 minutes. This willallow the amount of walling that can be built to beincreased and the earlier installation of othercomponents, such as floors and roof timbers. Thecompletion of a weathertight envelope allows brickworkto be taken off the critical path and for internal work,such as plastering, service installation and partitioning toprogress.

Improved thermal performance

The thermal insulation requirements of the BuildingRegulations call for attention to be given to the effectsof cold bridging. Consequently, when calculating U-Values for walls, heat loss through mortar joints mustbe taken into consideration.

By reducing the amount of mortar in any given area ofwall by at least 70%, compared to a traditional mortarjoint, heat loss through the mortar joints is reduced. In aclear cavity construction, an improvement of up to 10%in U-Values is possible.

Improved airtightness of construction

The thermal performance of the wall is also improved bythe effect of Thermalite Thin Layer Mortar on theairtightness of the construction. Reducing the airinfiltration rate of the masonry will, in turn, decrease theventilation heat loss through the fabric.

Airtightness test results for Thermalite 100mmblockwork and Thermalite Thin Layer Mortar, asconducted by the Building Services Research andInformation Association (BSRIA) were better than0.10m3.hr.-1m-2, the lowest possible score.

Reduced site wastage

A key benefit of Thermalite blocks is that they can beeasily cut, sawn and worked accurately on site. The precision cutting of blocks for use with ThermaliteThin Layer Mortar allows greater utilisation of theblocks, which can substantially reduce site wastage.

Mortar wastage can also be minimised with the batchmixing of small quantities of Thermalite Thin LayerMortar.

Improved construction quality

The combination of high tolerance blocks and thin layermortar allows greater accuracy to be achieved for theinternal face of a completed wall, which can provide asuitable substrate for the application of thin coat sprayplaster. This has the added advantage of fast applicationand quick drying times, resulting in further productivitygains.

Modern Methods of ConstructionModern Methods of Construction (MMC) describeproducts that are produced in off-site manufactureprocesses, or innovative systems and buildingtechniques.

Thermalite blocks used in a thin joint construction areaccepted as a Modern Method of Construction.

A growing percentage of housing funded by theHousing Corporation is now required to employ Modern Methods of Construction. Housing Associationsseeking funding from the Housing Corporation will be better placed to do so using Thermalite’s Thin JointMasonry system.


26

Thin Joint Masonry

Products

Thermalite Large Format blocksThermalite Large Format blocks have been specificallydesigned to complement the use of Thermalite ThinLayer Mortar and offer considerable productivity gains.

They are produced with face dimensions of 440 x 430mm in a range of thicknesses. This isequivalent to two normal concrete blocks, or twelvebricks.

Order quantities In a thin joint masonry construction, the maximum jointthickness is only 3mm. Consequently, when blocks witha face size of 440 x 215mm are selected an additional3.55% of blocks will be required to complete a m2 ofwalling.

When Large Format blocks with a face size of 440 x 430mm are selected for use in thin joint walling,an additional 4.3% of blocks will be required tocomplete a m2 of walling.

Thermalite Thin Layer MortarThermalite Thin Layer Mortar is factory-made andsupplied as a dry, pre-mixed, bagged product. It iscement-based and only requires adding to water to givea mortar that is easily applied and has high stability.

Thermalite Thin Layer Mortar is manufactured under aquality system approved by the BSI.

Thin layer mortar should be stored in dry conditions.

It is recommended that the mortar is used intemperatures at, or above 5°C.

Working below these temperatures, down to -6°C, isonly possible by protecting building elements inaccordance with Codes of Practice.

Product data – thin layer mortar

Bag weight 25kg

Approximate coverage (100mm thick walling) 15m2

Compressive strength 9.0 - 12.0N/mm2

Density 1800kg/m3

Thermalite productsThe high level of performance achieved by Thermaliteproducts, combined with the extensive block rangeoffered, ensures that cost effective solutions for wallsand foundations can be achieved with thin jointconstruction.

Thin joint construction is possible for use with all theThermalite products listed below.

• Turbo• Shield• Trenchblock/Tongue & Groove• Paint Grade Smooth• Hi-Strength 7• Hi-Strength Paint Grade Smooth• Hi-Strength Trenchblock• Party Wall


27

The Thermalite House

The principal objective of the ‘Thermalite House’ projectwas to establish that the thin joint system could safelybe used to construct the loadbearing inner leaf ofmasonry up to wall plate level, without the stabilisingeffect of the brickwork outer leaf and to complete thisprocess quickly and accurately.

The successful results indicated that brickwork could betaken off the critical path and the shell madeweatherproof far earlier in the building programme.

The project also enabled the problems that a typicalbuilder would face when using the thin joint process forthe first time, to be identified, and solved.

Pre-construction planning and partnering agreementswith other component suppliers were found to offersignificant advantages in the construction of thin jointmasonry.

Design datum levels for floors and wall plate were accommodated, as well as the minimising of cutting, by the pre-planned inclusion of standard and cut blocksinto the large format block structure.

Following the successful completion of the project,Thermalite can be recommended and endorsed for thebuilding of the loadbearing inner leaf of a two-storeyhouse, up to roof level, using the thin joint system.

The Thermalite thin joint house trials resulted inacceptance of the system as one of the HousingForum's Demonstration Projects on a site in conjunctionwith Gleeson Homes (North East).

‘The adoption of thin joint in the design and build process will significantly increase speed and efficiency of construction, reduce wastage on site and improve SAP energy ratings.’Conclusions• The inner leaf of a 3 bedroom detached house,

including floor and roof truss installation, was completed in a combined time of just 16 hours. Only a standard team of 2 block layers and one labourer was used.

• The quick setting properties of Thermalite Thin Layer Mortar, combined with the inherent dimensional accuracy of the blocks, aided stability and allowed rapid vertical progress.

• Temporary buttressing was found to be unnecessary at ground floor level, even prior to the inclusion of the first floor joists.

• Because of the design of the first floor walls, temporary buttressing was found to be necessary to aid stability prior to roof truss placement.

• After wall plate location, roof truss placement and restraint strapping, temporary bracing of the upper floor walls could be safely removed without risk to the structure.


28

Thin Joint Masonry

Comparative resultsThe times taken to build one wall panel with corner, ineach of the wall types chosen were as follows:

Conclusions• A simple wall built with standard Thermalite Shield

blocks and thin layer mortar can be erected almost twice as fast as a similar one built with aggregate blocks and general purpose mortar.

• A simple wall built with standard Thermalite Shield blocks and thin layer mortar can be erected 70% faster than a similar wall built with general purposemortar.

• A simple wall built with Large Format blocks and thin layer mortar can be erected 35% faster than a similar wall built with standard size material.

• The erected Thermalite Thin Layer Mortar panels were set and stable within half an hour of laying. This did not apply to the general purpose mortar panels.

• An estimated 12% increase in the rate of laying blocks was achieved by pump application of the mortar replacing use of the hand scoop. Further gains would be achieved by combining the benefits of the pump and Large Format blocks, especially with plain panels of walling.

Speed trial reportThe following is a synopsis of independent tests conducted by Percy Howes, Chartered Surveyors, using Thermalite.

25

Rate of laying(m2 per hour)

20

15

10

5

0

Aggregateblocks &general purposemortar

9.72

Shieldblocks &general purposemortar

Shieldblocks &thin layermortar

LargeFormatblocks &thin layermortar

11.01

20.66 21.26

Wall type Time taken

Aggregate blocks and general purpose mortar 32 mins : 30 secs

Shield blocks and general purpose mortar 28 mins : 50 secs

Shield blocks and thin layer mortar 16 mins : 20 secs

Large Format blocks and thin layer mortar 14 mins : 40 secs

IntroductionThe tests were conducted to determine the effects ofreplacing general purpose mortar with Thermalite ThinLayer Mortar in typical inner leaf masonry constructions.

SpecificationL-shaped walls were constructed, each 100mm thickand of a similar length (4.5m x 1.5m), for stability and toreflect normal building practice.

The wall types chosen for comparison were as follows:

• Aggregate blocks and general purpose mortar

• Thermalite Shield blocks and general purpose mortar

• Thermalite Shield blocks and thin layer mortar

• Thermalite Large Format blocks and thin layer mortar

TestingThe speed tests were undertaken and completed over atwo-day period. The same operatives undertook eachtest to rule out the human factor.

Rate of laying The average block laying rates calculated from thespeed trials are shown in the graph above.


29

InstallationThe build process is as simple as with general purpose mortar. The skillsrequired are very similar. It is necessary, for example, to maintain regularchecks of level and line.

MixingThe correct application and performance of ThermaliteThin Layer Mortar is reliant on attention being given tothe mixing procedure.

Thermalite Thin Layer Mortar must be mixed in asuitable mixing tub (always add mortar to water) at arate of one 25kg bag of mortar to 5.75-6.0 litres ofclean water. Mix with an electrical slow-speed drill witha whisk attachment for approximately 2-3 minutes.Allow to stand for 5 minutes to enable mortar to gain itsproperties. A short final re-mix will create folds in themortar which is indicative of correct consistency.

The mortar remains workable in normal conditions in thetub for not less than 2 hours, with occasional re-mixing.No additional mixtures or water should be added. To minimise wastage, the rate of mixing should beequated to the rate of use.

In common with all types of masonry, Thermalite thin joint blockwork should generally be constructed to BS 5628: Part 3 ‘Code of Practice for the use ofMasonry – Materials, Components, Design andWorkmanship’.

Setting outThe most important aspect to achieving the full benefitsof thin joint masonry lies in the quality of the basecourse. Base course blocks must be bedded in generalpurpose mortar and laid level, aligned, vertical, and befully set before commencement of thin jointconstruction. The use of a laser level has been found tobe beneficial in this process. It must be stressed thatinaccuracy in this base course cannot easily becorrected in the subsequent thin layer mortar beds.

Any damp proof membrane should be incorporated intothe base course bed joint.

Pre-construction planning will allow maximumadvantage to be taken of the thin joint system,particularly with Large Format blocks.

Thin Joint Masonry combines a thin mortar bed of 2-3mm with standard, close-tolerance, Thermaliteblocks. This will not course with the standard brickcoursing of the outer leaf.

For the inner leaf, a mix of standard, large format andcut blocks can be used to meet design datum levels forfloors and roof plate. A thicker bed of thin layer mortar,or general-purpose mortar, can be used when makingup to a level of a few millimetres.


30

Thin joint masonry

Installation

Wall tiesWall ties designed for use with general purpose mortarare not suitable for use with thin joint masonry. Helicalwall ties are most suitable and can be hammered intothe Thermalite blocks to a minimum depth of 50mm(90mm with Turbo material).

Adjustable face fix ties may also be used. Helical tiescan be obtained with a retaining clip allowing installationof cavity insulation without loss of performance.

Ties should be installed at not less than 2.5 ties persquare metre (900mm centres horizontally, 450mmvertically). Additional ties will be required aroundopenings and at movement joints, at centres not morethan 300mm and within 225mm of the unreturned orunbonded edge.

It is important to ensure that the wall is set and stablebefore application of the ties. The tie manufacturer’sinstructions should be followed, and special tools usedwhere recommended.

Wall ties should either comply with DD140 or BS EN845-1 and should be made of material as references 1 or 3 in BS EN 845 Table A1, austenitic stainlesssteel. To satisfy the requirements of ApprovedDocument A, ‘Structure’, wall ties should be selected inaccordance with Table 5 of that document.

LayingMinor adjustments to the build process should beconsidered to gain most benefit from the product. For example, applying mortar to the exposed block perp-ends whilst retained in the pack. Alternatively,blocks could be placed on a flat surface which willenable a number of perpendicular joint faces to bemortared to a consistent standard in one operation.

Use of the recommended notched scoop will deliver theappropriate depth and spread of mortar to the block bedsurface and perpendicular joint. Alternatively, andparticularly when constructing long runs of walling, Thin Layer Mortar may be applied using a proprietarypumping system.

Subject to ambient conditions, the exposed mortar bedwill remain workable for up to 20 minutes. However,once blocks have been laid, initial setting takes placewithin 10 minutes; any adjustment should be madeduring the correction period.

CuttingIt is recommended that the blocks should be cut to sizeusing either a powered band saw, reciprocating saw orblock saw. To ensure the correct meeting of the jointingsurfaces, attention to the squareness and clean lines ofthe cut face is necessary.


31

Movement jointsIn common with all cement-based products, Thermalitewalls are subject to movement as the walls dry out. BS 5628: Part 3 recognises that drying out movementoccurs in all types of concrete masonry andrecommends that such movement should be consideredat the design stage.

It is particularly important to provide movement joints inlong runs of walls such as those that occur in industrial,commercial and large residential buildings. It is alsoimportant to provide movement joints in external solidwalls and in the outer faces of external cavity walls. Thefollowing general recommendations apply to aircrete:

• Blockwork walls in excess of 6m in length should be divided up into a series of rectangular panels, separated by movement joints at no more than 6m centres.

• Where a wall is continuous at internal or external corners, the location of the first joint should be approximately 3m from the angle.

Movement may be accommodated using movementjoints or bed joint reinforcement/movement controlmesh, or a combination of the two. Where a movementjoint is required, this should be built in as workproceeds, with the most common form being a dryvertical butt joint.

Bed joint reinforcement/movement control meshIn walls containing openings, or in areas where stress isanticipated, movement joints may need to be provided atmore frequent intervals than 6m. Alternatively, themasonry should be reinforced with bed jointreinforcement of adequate length to distribute any

stresses into adjacent blockwork and extending at least600mm each side and 430mm above and below eachopening.

Optimum performance can be achieved with theprovision of bed joint reinforcement/movement controlmesh for the full perimeter at levels as indicated.

As the mortar joint is thin, the reinforcement must be nomore than approximately 1.5mm thick. Proprietarystainless steel, galvanised or steel mesh bed jointreinforcement, manufactured for use with thin jointmasonry, is available for use with Thermalite in thin jointblockwork. Always follow manufacturers’ instructions.Alternatively, a GRP (glass reinforced plastic) movementcontrol mesh may be used where reinforcement of themasonry is not required. Please contact Hanson’sProduct Services department for further advice.

Wall junctionsAt wall junctions where either a movement joint islocated, or where normal bonding is not possible,straight joints may be used provided that ties are built inacross the joint.

Other components, e.g. joist hangers, lintels, cavity trays,restraint straps, etc. can be accommodated by chasingor cutting of the blockwork, as necessary.

Supervision and workmanshipAs with all masonry, the level of supervision duringinstallation of Thermalite thin joint blockwork and theassociated structure must be sufficient to ensure thequality of workmanship as described in BS 5628: Part 3and Annex A thereof.


32

Thin Joint Masonry


33

3 PerformanceThermal insulation 34

Air permeability 42

Fire protection 43

Sound insulation 44

Moisture penetration 50

Frost resistance 52


34

A Thermalite wall solution can exceed thesuggested U-Values for Part L 2006, and offersthe added benefits of:• Thermal comfort: The inherent thermal mass of

Thermalite blocks prevents overheating in summer, whilst at the same time storing heat and solar gains, dispatching this in colder periods.

New research shows that this can save significant amounts of energy compared to lightweight timber frame, whilst at the same time providing the homeowner with a comfortable environment all year round.

• Air tightness: Thermalite blocks are highly resistant to the passage of air and have proven results in air seepage tests, see page 36.

• Robustness: Unlike some alternative walling solutions,Thermalite blocks offer long-term durability, in addition to low U-Values.

• Expert technical advice: Hanson’s Product Services department offers technical advice on building regulations, including thermal calculations and energyratings.

Introduction to Part LAfter a long period of consultation within the buildingindustry, the final version of the Part L (Conservation ofFuel and Power) document (2005) was released on16th March 2006 as the instrument for improving theenergy performance in all new buildings from 6th April2006. Headlining these changes has been the aim toimprove the energy performance of all new buildings,and alterations or extensions to existing buildings.

The focus of the new regulations has moved away fromprescribed U-Values for each element of the buildingfabric, and now requires a carbon emissions evaluationfor the building as a whole. This will involve a substantialimprovement in the required U-Values for each buildingelement, which is likely to move within an acceptablerange dependent on the type of building and otherrelated energy use solutions.

The new document has been revised into the followingfour sections:

• Part L1A Work in new dwellings.

• Part L1B Work in existing dwellings.

• Part L2A Work in new buildings other than dwellings.

• Part L2B Work in existing buildings other than dwellings.

The previous version of Part L offered three routes tocompliance, The Elemental Method, Target U-ValueMethod and the Carbon Index Method. These three arenow replaced by the DER (Dwelling CO2 EmissionRate), which is an improved methodology for calculatingthe energy performance in dwellings.

The Target CO2 Emission Rate (TER) is the minimumenergy performance requirement for new dwellings. It isexpressed in terms of the mass of CO2, in units of kgper m2 of floor area per year emitted as a result of theprovision of heating, hot water, ventilation and internalfixed lighting for a standardised household whenassessed using approved licensed calculation tools suchas SAP 2005.

The main emphasis for new-builds remains animprovement in the building fabric to reduce heat loss,with a steer clearly towards the specification ofinnovative measures, including solar collectors andventilation with heat recovery, where appropriate. The use of non-fossil fuel heating such as Geothermaland Biomass energies will also improve the energyperformance of a dwelling.

Parts L1A: ‘Work in new dwellings’ and L2B: ‘Work inexisting dwellings’ state that reasonable provision shallbe made for the conservation of fuel and power inbuildings by means of:

a) Limiting:i. Heat losses through the fabric of the buildings ii. Excessive solar gainsiii. Heat gains and losses from pipes, ducts and vessels

used for space heating, space cooling and hot water storage.

b) Providing energy efficient and properly commissionedfixed building services with effective controls.

c) Providing to the owner, sufficient information about the building and its building services so that the building can be operated and maintained in such a manner as to use no more fuel and power than is reasonable in the circumstances.

d) Minimising technical risk.

Thermal insulationThermalite offers high levels of performance for wall, floor and belowground constructions, satisfying the requirements of Building Regulationsand the needs of builders and designers.


35

Key aspects of the changesA summary of the principal changes contained withinthe revised Approved Document is described below.

For all buildings:

• A significant increase in the thermal insulation performance of the building envelope to be introduced.

• Improving the standard of detail design and workmanship in order to reduce gaps in construction and cold bridging.

• Raising the standard of air-tightness to reduce unnecessary ventilation and including the requirementof air permeability tests to be carried out on all new builds.

• Improving the standard of system insulation (pipework, ducts, etc).

L1A (Work in new dwellings) and L2A (Work in

new buildings other than dwellings):• Avoiding solar overheating.

• Improving the SAP calculation method, removing the Target U-Value, Elemental Method and Carbon Index method, and introducing a new TER (Target CO2

Emission Rate) to replace the existing methods with amore comprehensive calculator, SAP 2005, which willgive a DER (Dwelling CO2 Emission Rate).

• Improving the requirements for properly setting up and adjusting heating and hot water systems and their controls.

• Improving the requirements for the supply of operating and maintenance instructions with heating and hot water systems.

• Improving performance standards for internal lighting efficiency such as low energy lighting.

• Improving the standard of system insulation (pipework, ducts, etc).

• Raising the standard of air-tightness to reduce unnecessary ventilation and including the requirementof air permeability tests to be carried out on all New Builds.

L1B (Work in existing dwellings) and L2B (Work

in existing buildings other than dwellings):• Limiting heat gains and losses:–

a) Through thermal elements and other parts of the building fabric.

b) From pipes, ducts and vessels used for space heating, space cooling and hot water services.

• Providing and commissioning energy efficient fixed building services with effective controls.

• Providing to the owner, sufficient information about the building and its building services, so that the building can be operated and maintained in such a manner as to use no more fuel and power than is reasonable in the circumstances.

Air permeabilityIn addition to the increase of the required U-Values, thenew regulations recommend that the air permeabilitylimits be set at 10m3/hr/m2 (at 50 pascals pressure).Thermalite blocks have a microcrystalline cellularstructure that is highly resistant to the passage of air;these impressive performance levels are confirmed byindependent tests undertaken by BSRIA, detailedbelow:

Report 15055A/1

100mm Thermalite Shield blocks 0.1m3. hr-1. m-2

with acrylic sealed joints.

100mm Thermalite Shield blocks 0.1m3. hr-1. m-2

thin layer mortar joints.

Report 15919A

100mm Thermalite Turbo blocks 0.18m3. hr-1. m-2

with acrylic sealed mortar joints.

Report 16918A


with acrylic sealed mortar joints.


with standard mortar joints.

The conclusion can be drawn, that when used asrecommended, thin layer mortar joints offer a higherlevel of sealing performance than standard mortar joints.


The use of non-fossil fuel heating such as Geothermaland Biomass energies will improve the energyperformance of a dwelling and assist in achieving aDER (Dwelling CO2 Emission Rate) v TER (Target CO2

Emission Rate) pass, while inefficient carbon fuel suchas oil, LPG and electricity will likely require furtherimprovements within the build, such as improved U-Values within elements and or the use of zero carbontechnology such as solar, to achieve a DER v TER pass.

Low and zero carbon systemsWhen using low or zero carbon technologies asmentioned above, there are new technical referencesfrom the Department for Communities and LocalGovernment (DCLG) that give guidance on ways ofcomplying when providing heating and hot waterservices systems and full information of the benefits ofthese zero carbon technologies, such as Geothermaland Biomass.

For further information, please refer to:www.communities.gov.uk

36

Performance

Thermal insulation

Poorest acceptable SEDBUK (standard

efficiency of domestic boilers in the UK)From April 2005 the following changes to the SEDBUKefficiency has been altered to the following as minimumvalue.

Mains natural gas 86%, LPG 86%, Oil 85%Oil combi boiler 82%

Heating and hot water system controlsFor systems incorporating hot water storage, specificlevels of insulation are required, as well as efficientcontrol and performance specification. Reasonableprovision must also be made to insulate pipes andducts.

Thermalite success with air seepage testsThermalite products have achieved success in recent airseepage tests carried out by leading house builderDavid Wilson Homes. Using Thermalite aircrete blocksthroughout the inner leaf of a cavity wall, the houses allachieved less than the required airflow rate of less than10m3/hm2, tested at 50 pascals. These plots,constructed in traditional mortar, returned results thatranged from 2.60m3/hm2 to 8.81m3/hm2, with thehighest figure recorded for an uncompleted house.

Plot number Airflow rate

104 2.60m3/hm2

137 8.81m3/hm2

140 3.96m3/hm2

143 5.90m3/hm2

Solar gainAs required by Part L1 (a) (ii), provisions should bemade to limit internal temperature rise due to solargains. This can be done by an appropriate combinationof window size and orientation, solar protections throughshading and other solar control measures, ventilation(day and night) and high thermal capacity. CE129Reducing Overheating – A Designers Guide, offersguidance on strategies to control overheating.

Other requirements for dwellingsPoorest acceptable U-Values

Since there are no longer prescribed constructions thatcan assure compliance with Part L 2006, it isreasonable to assume that U-Values in the range listedbelow will prove acceptable for the new standardsunder the majority of situations. For details of Thermalitewall solutions to meet 0.30W/m2.K and 0.27W/m2.K,please refer to the tables on pages 38-41.

Walls

0.30W/m2.K to 0.27W/m2.KFloors

0.22W/m2.K to 0.20W/m2.KRoof (horizontal ceiling)

0.16W/m2.K to 0.13W/m2.KWindows & doors

1.8W/m2.K to 1.5W/m2.K

The parameters will generally assume gas to be theprimary heating source, a boiler SEDBUK of no lessthan 86% and the air-tightness default of10m3/hour/m2.


37

Internal and external lighting systemsA way of showing compliance would be to providelighting fittings (including lamp, control gear and anappropriate housing, reflector, shade or diffuser or otherdevice for controlling the output light) that only takelamps having a luminous efficiency greater than 40lumens per circuit-Watt. Circuit-Watts means the powerconsumed in lighting circuits by lamps and theirassociated control gear and power factor correctionsequipment, fixed energy efficient light fittings thatnumber not less than:

a) One per 25m2 of dwelling floor area (excludinggarages) or part thereoforb) One per four fixed lighting fittings.

Limiting thermal bridging at junctions andaround openingsThe building fabric should be constructed to avoidsignificant thermal bridges and gaps in insulation layersin the various elements of the fabric, at joints betweenthe various elements and at the edges of elements suchas those around window and door openings.

To meet the requirements of Part L, the followingminimum depths of cut Thermalite (excluding mortar), ofwidth matching that of the inner leaf block will comply*:

Turbo 50mm, Shield 68mm, Party Wall 72mm

The window frame should overlap the closer block by aminimum of 30mm, (see Detail 1. left) and in verysevere exposure zones, the masonry should be rebated,(see Detail 2 below).

Please contact the DCLG for more information.Fixed external lighting means lighting fixed to anexternal surface of the dwelling supplied from theoccupier’s electrical system.

Provision should be made to enable effective controland/or the use of efficient lamps such that:

a) Either: Lamp capacity does not exceed 150W perlight fitting and the lighting automatically switches off:i. When there is enough daylight.ii. When it is not required at night.orb) The light fittings have sockets that can only be usedwith lamps having efficiency greater than 40 lumens percircuit-Watt.

ConservatoriesTogether with a definition, clear guidance is given onconservatories which are attached to dwellings anddependent on how they are connected to the dwelling,provides ways of achieving compliance.

Wall tiesThe type and number of wall ties can have a significanteffect on the U-Values due to thermal bridging of thecavity and insulation and must be considered in thecalculation of all U-Values. Information can be gainedfrom your wall tie manufacturer or from a qualifiedenergy assessor.

Thermalite inner leaf

d.p.m

Thermalite of suitable depthor proprietary cavity closer

Detail 2 Window frame overlapping cavity closer – rebated reveal

for very severe exposure zones

d.p.m

Thermalite of suitable depth

Detail 1 Window frame overlapping cavity closer – flush reveal

*See note on page 64


38

Performance

Thermal insulation

Table 1- Partially filled cavityUsing insulation type: PIR - Polyisocyanurate/Celotex/Kingspan/Xtratherm 0.023W/m.KGeneral purpose mortar joints (10mm)

Insulation Turbo Shield Hi-Strength 7thickness 100mm 150mm 100mm 150mm 100mm 150mm

25mm - - - - - -

35mm 0.30 0.27 - 0.29 - 0.30

40mm 0.28 0.26 0.30 0.27 0.30 0.28

45mm 0.26 0.24 0.28 0.26 0.28 0.26

50mm 0.25 0.23 0.26 0.24 0.27 0.25

25mm - - - - - -

35mm - 0.28 - 0.30 - -

40mm 0.29 0.26 0.30 0.28 - 0.29

45mm 0.27 0.25 0.28 0.26 0.29 0.27

50mm 0.26 0.23 0.27 0.25 0.28 0.26

Thin layer mortar (<3mm)

Turbo Shield Hi-Strength 7100mm 150mm 100mm 150mm 100mm 150mm

- 0.29 - - - -

0.29 0.25 - 0.28 - 0.30

0.27 0.24 0.29 0.26 0.30 0.28

0.25 0.23 0.27 0.25 0.28 0.26

0.24 0.22 0.26 0.24 0.26 0.25

- 0.30 - - - -

0.30 0.26 - 0.29 - -

0.28 0.25 0.30 0.27 - 0.29

0.26 0.24 0.28 0.26 0.29 0.27

0.25 0.22 0.26 0.24 0.27 0.25

Table 2 - Fully filled cavityUsing insulation type: mineral wool 0.033W/m.K

General purpose mortar joints (10mm)


65mm - 0.28 - 0.30 - -

75mm 0.29 0.26 0.30 0.28 - 0.29

85mm 0.26 0.24 0.28 0.26 0.28 0.27

90mm 0.26 0.23 0.27 0.25 0.27 0.26

100mm 0.24 0.22 0.25 0.23 0.25 0.24

65mm - 0.29 - - - -

75mm 0.30 0.27 - 0.29 - 0.30

85mm 0.27 0.25 0.29 0.26 0.29 0.28

90mm 0.26 0.24 0.27 0.25 0.28 0.27

100mm 0.24 0.22 0.25 0.24 0.26 0.25



0.30 0.27 - 0.29 - -

0.28 0.25 0.30 0.27 - 0.28

0.26 0.23 0.27 0.25 0.28 0.26

0.25 0.22 0.26 0.24 0.27 0.25

0.23 0.21 0.24 0.22 0.25 0.23

- 0.28 - 0.30 - -

0.29 0.26 - 0.28 - 0.29

0.26 0.24 0.28 0.26 0.29 0.27

0.25 0.23 0.27 0.25 0.28 0.26

0.24 0.21 0.25 0.23 0.26 0.24

Table 3 - Solid wall


Insulation Turbo Shield Hi-Strength 7thickness 215mm 265mm 300mm 190mm 200mm 200mm 215mm

16mm render - - - - - - -

- 0.28 0.26 - - - -

0.27 0.25 0.23 - - - -

0.24 0.22 0.21 0.27 0.27 0.28 0.28

0.27 0.25 0.23 - - - -

0.24 0.22 0.21 0.27 0.27 0.28 0.28

0.26 0.24 0.22 - - - -

0.23 0.21 0.20 - - - -

Tile hanging 0.28 0.25 0.24 - 0.30 - -insulation external

0.25 0.23 0.22 0.29 0.28 0.30 0.30

Wonderwall 0.23 0.22 0.22 0.26 0.26 0.27 0.27

0.24 0.22 0.22 0.27 0.27 0.28 0.28


Turbo Shield Hi-Strength 7215mm 265mm 300mm 190mm 200mm 200mm 215mm

- 0.29 0.27 - - - -

0.29 0.25 0.24 - - - -

0.25 0.23 0.21 0.30 0.30 - -

0.22 0.20 0.19 0.26 0.26 0.27 0.27

0.25 0.23 0.21 0.30 0.30 - -

0.22 0.20 0.19 0.26 0.26 0.28 0.28

0.24 0.22 0.20 0.28 0.28 - -

0.21 0.20 0.19 0.25 0.24 - -

0.26 0.23 0.22 - - - -

0.24 0.21 0.20 0.28 0.27 0.29 0.29

0.22 0.20 0.19 0.25 0.25 0.27 0.26

0.23 0.20 0.19 0.26 0.26 0.28 0.27


39

Finish

12.5mm plasterboard on dabs





13mm light weight plaster





Finish











Finish

30mm Lafarge Thermalcheck K board on dabs




50mm Gyproc Thermaline Super board on dabs

60mm Gyproc Thermaline Super board on dabs

42.5mm Kingspan Kooltherm K17 insulated drylining

52.5mm Kingspan Kooltherm K17 insulated drylining

40mm insulation laid between battens PIR 0.023W/m.K with 12.5mm plasterboard

50mm insulation laid between battens PIR 0.023W/m.K with 12.5mm plasterboard



Please note that this table assumes a resistance figure of 0.64m2.K/W for the

clear cavity space of no smaller than 25mm. Thermal massThe inherent thermal mass of Thermalite blocks helps toachieve a comfortable room temperature, preventingoverheating in summer, whilst at the same time storingheat and solar gains and dispatching this in colderperiods. New research has showed that conventionalmasonry houses that take advantage of their inherentthermal mass can save a significant amount of energyover their lifetime, compared to lightweight timber framehouses.

The thermal mass of masonry homes reduces the needfor air conditioning, which is particularly relevant interms of the predicted increase in global temperature inthe 21st century. Additional savings can also beachieved through passive solar design, reducing theconsumption of winter heating fuel.

These savings can offset the slightly higher level ofembodied CO2 in a masonry house over as little as tenyears, and lead to a lower whole life CO2.

Specific heat capacityThe mean specific heat capacity of dry Thermalite overthe temperature range 20° - 100° is 1.05kJ/kg°C.

The effect of thin joint masonryThe use of Thermalite Thin Layer Mortar, with a bedjoint thickness of approximately 2.5mm, can provide asignificant contribution to improving the overall U-Valueof a masonry wall without the need to increase theamount of insulation.

This is seen at its most effective in solid wallconstructions, as shown in Table 3.

For cavity constructions, whilst the contribution toimproved thermal performance of thin layer mortar isless than that for the solid walls, useful improvementson U-Values can be gained, in addition to the airtightness benefits offered by thin joint construction.


40

Performance

Thermal insulation

Table 4 - Block-to-block partially filled cavityUsing insulation type: PIR - Polyisocyanurate/Celotex/Kingspan/Xtratherm 0.023W/m.K



25mm 0.30 0.27 - 0.29 - 0.30

35mm 0.26 0.24 0.27 0.25 0.28 0.27

40mm 0.25 0.23 0.26 0.24 0.27 0.25

45mm 0.23 0.22 0.24 0.23 0.25 0.24

50mm 0.22 0.22 0.23 0.22 0.24 0.23

25mm - 0.28 - 0.30 - -

35mm 0.27 0.25 0.28 0.26 0.29 0.27

40mm 0.26 0.23 0.27 0.25 0.28 0.26

45mm 0.24 0.22 0.25 0.24 0.26 0.24

50mm 0.23 0.21 0.24 0.22 0.25 0.23



0.28 0.25 0.30 0.27 - 0.29

0.25 0.23 0.26 0.24 0.27 0.26

0.24 0.22 0.25 0.23 0.26 0.24

0.22 0.20 0.24 0.22 0.24 0.23

0.21 0.20 0.23 0.21 0.23 0.22

0.29 0.26 - 0.28 - 0.30

0.26 0.23 0.27 0.25 0.28 0.26

0.24 0.22 0.26 0.24 0.27 0.25

0.23 0.21 0.24 0.23 0.25 0.24

0.22 0.20 0.23 0.22 0.24 0.23

Table 5 - Block-to-block fully filled cavityUsing insulation type: mineral wool 0.033W/m.K



50mm - 0.24 - 0.30 - -

65mm 0.27 0.22 0.29 0.27 0.30 0.28

75mm 0.25 0.20 0.27 0.25 0.27 0.26

85mm 0.24 0.19 0.25 0.23 0.25 0.24

90mm 0.23 0.19 0.24 0.22 0.24 0.23

100mm 0.21 0.18 0.22 0.21 0.23 0.21

50mm - 0.29 - - - -

65mm 0.28 0.26 0.30 0.28 - 0.29

75mm 0.26 0.24 0.27 0.24 0.28 0.26

85mm 0.24 0.22 0.25 0.23 0.26 0.25

90mm 0.23 0.22 0.24 0.23 0.25 0.24

100mm 0.22 0.20 0.23 0.21 0.23 0.22



0.30 0.26 - 0.29 - 0.30

0.26 0.23 0.28 0.25 0.29 0.27

0.24 0.22 0.26 0.24 0.26 0.25

0.23 0.21 0.24 0.22 0.24 0.23

0.22 0.20 0.23 0.21 0.24 0.22

0.20 0.19 0.21 0.20 0.22 0.21

- 0.27 - 0.30 - -

0.27 0.24 0.29 0.26 0.30 0.28

0.25 0.22 0.26 0.24 0.27 0.25

0.23 0.21 0.24 0.23 0.25 0.24

0.22 0.20 0.24 0.22 0.24 0.23

0.21 0.19 0.22 0.21 0.23 0.21

Please note that this table assumes a resistance figure of 0.644m2.K/W for the clear cavity space of no smaller than 25mm.

All external leaves are to be 100mm Thermalite Shield with a rendered finish.


41

Finish











Finish














42

Performance

Air permeabilityThermalite blocks have a micro-crystalline cellular structure that is highlyresistant to the passage of air. The fact that air permeability contributes toboth the thermal and sound insulation performance of a building isrecognised in the Building Regulations.

Report 15055A/1100mm Thermalite Shield blocks 0.1m3. hr-1. m-2 with acrylicsealed joints 100mm Thermalite Shield blocks 0.1m3. hr-1. m-2 thin layer mortarjoints

Report 15919A100mm Thermalite Turbo blocks 0.18m3. hr-1. m-2 with acrylicsealed mortar joints

Report 16918A 100mm Thermalite Turbo blocks 0.22m3. hr-1. m-2

with acrylic sealed mortar joints


with standard mortar joints

The conclusion can be drawn, that when used as recommended,thin layer mortar joints offer a higher level of sealing performancethan standard mortar joints

Air permeabilityIn addition to the increase of the required U-Values, Part L of the Building Regulations recommends that theair permeability limits be set at 10m3/hr/m2

(at 50 pascals pressure). Thermalite blocks have a micro-crystalline cellular structure that is highly resistantto the passage of air; these impressive performancelevels are confirmed by independent tests undertakenby BSRIA, detailed below:


43

Fire protectionAll Thermalite products provide excellent fire protection. They are classified as A1, non-combustible in accordance with BS EN 771-4.

Compliance with Building RegulationsThe following requirements of the Building Regulationscan therefore be easily satisfied:

1. Means of escape.

2. Internal fire spread (surfaces): surfaces within the building should be such as to inhibit the spread of flame.

3. Internal fire spread (structure): the structure shall be designed so as to inhibit the spread of fire and retain its stability for a reasonable period.

4. External fire spread: the external surfaces of the building shall offer adequate resistance to the spread of fire from one building to another.

CombustibilityThermalite blocks are classified as non-combustible inaccordance with the Building Regulations, and ClassA1, non-combustible, in accordance with BS EN 771-4.

Fire resistanceInformation contained in the Building Regulations and inBS 5628–3 confirms that Thermalite may be used toachieve fire resistance grades as given in the followingtable, and is consistent with the information contained inBS EN 1996-1-2. All data has been adjusted to suitavailable block sizes.

Table 6 – Fire resistance based on BS 5628-3

Wall type Fire resistance grade w (hr) for block thickness (mm)1hr 2hr 3hr 4hr 6hr

Non-loadbearing singleleaf unplastered 75 75 75 100 150

Loadbearing single leafunplastered 90 100 140 190 215

Non-load bearing cavitywall (per leaf) unplastered 75 75 75 75 90

Loadbearing cavity wall(per leaf) unplastered 90 100 140 150 150

Surface spread of flameIt is often sufficient that materials should not be readilyignitable and that their tendency to spread flame belimited.

The surface spread of flame tests in BS 476: Part 7define spread of flame as ‘propagation of a flame frontover the surface of a product under the influence ofproposed irradiance’.

Thermalite blocks have a Class 0 resistance to surfacespread of flame as described in the BuildingRegulations.

Table 7 - Fire resistance based on thickness

Wall type Fire resistance grade (hr) for block thickness (mm)0.5hr 1hr 1.5hr 2hr 3hr 4hr

Thermalite Turbo Load bearing, single leaf, unplastered (plastered)a > 1.0 100 100 125 125 150 150

(100) (100) (115) (125) (150) (150)

a > 0.6 100 100 100 125 140 150

(100) (100) (100) (100) (125) (150)

Thermalite Turbo Non load bearing, single leaf, unplastered (plastered) 100 100 100 100 100 100

(100) (100) (100) (100) (100) (100)

Thermalite Shield, Paint Grade Smooth, Party Wall, Hi-Strength Load bearing, single leaf, unplastered (plastered) a > 1.0 90 90 100 100 140 150

(90) (90) (90) (90) (100) (100)

a > 0.6 90 90 100 100 120 150

(90) (90) (90) (90) (100) (100)

Thermalite Shield, Paint Grade Smooth, Party Wall, Hi-Strength Non load bearing, single leaf unplastered (plastered)

75 75 75 75 75 100

(75) (75) (75) (75) (75) (100)

Note: a = the proportion of load on a wall


44

Performance

Sound insulationHanson offers a wide range of Thermalite block solutions for walls andfloors, to satisfy the performance standards of Part E of the BuildingRegulations, as well as the specific needs of builders and designers.Hanson solutions to Part E offer high levels of performance and canachieve compliance through Robust Details, Pre-Completion Testingand Alternate Design and Test.

BackgroundUnwanted sound, particularly in dwellings, has in recentyears given rise to an increasing number of complaintsby occupiers.

It was recognised that existing standards, of bothregulation and workmanship, were failing to protectresidents adequately. Rising housing densities, changesof lifestyle, technology, perception and tolerance had allcontributed to the pressure for change.

The overall aim of the amendments to Part E is toimprove the sound insulation, through betterspecification and workmanship, both between andwithin dwellings, as well as between rooms in hostels,hotels and residential homes. The scope has beenextended to cover reverberation in common parts ofblocks of flats and acoustic conditions in schools.

The changes to the Approved Document E providesome of the technical specifications and solutions thatmay be adopted to satisfy the new statutoryrequirements; as an alternative to Pre-CompletionTesting, the use of Robust Details will demonstratecompliance with Part E for new dwellings.

Performance requirementsE1 Protection against sound from other parts of thebuilding and adjoining buildings

Dwelling-houses, flats and rooms for residentialpurposes shall be designed and constructed in such away that they provide reasonable resistance to soundfrom other parts of the same building and fromadjoining buildings.

E2 Protection against sound within a dwelling-house etc.

Dwelling-houses, flats and rooms for residentialpurposes shall be designed and constructed in such away that:

a) Internal walls between a bedroom or a roomcontaining a water closet and other rooms.

b) Internal floors provide reasonable resistance tosound.

Limitations

Requirement E2 does not apply to:

a) An internal wall which contains a door.

b) An internal wall which separates an en suite toiletfrom the associated bedroom.

c) Existing walls and floors in a building which is subjectto a material change of use.

E3 Reverberation in the common internal parts of buildingscontaining flats or rooms for residential purposes

The common internal parts of buildings which containflats or rooms for residential purposes shall be designedand constructed in such a way as to prevent morereverberation around the common parts than isreasonable.

Limitations

Requirement E3 only applies to corridors, stairwells,hallways and entrance halls which give access to theflat or room for residential purposes.

E4 Acoustic conditions in schools

1. Each room or other space in a school shall bedesigned and constructed in such a way that it has theacoustic conditions and the insulation againstdisturbance by noise appropriate to its intended use.

2. For the purpose of this Part – “school” has the samemeaning as in section 4 of the Education Act 1996(4);and “school building” means any building forming aschool or part of a school.


45

Pre-Completion TestingAs part of the construction process, sound insulationtesting to demonstrate compliance with RequirementE1, should be carried out on site. In the ApprovedDocument this is referred to as Pre-Completion Testing.

Under Regulation 20A and Regulation 12A, the duty ofensuring that appropriate sound insulation testing iscarried out falls on the person carrying out the buildingwork, who is also responsible for the cost of the testing.

Testing should be carried out for:(a) Purpose built dwelling-houses and flats.(b) Dwelling-houses and flats formed by materialchange of use.(c) Purpose built rooms for residential purposes.(d) Rooms for residential purposes formed by materialchange of use.

The Pre-Completion Test regime and procedure aredetailed in Section 1 of the Approved Document.

Table 10 - Laboratory values for new internal walls and floorswithin dwelling houses, flats and rooms for residentialpurposes, whether purpose built or formed by material changeof use.

Airborne sound insulationRw dB(Minimum values)

Walls 40

Floors and stairs 40

To satisfy Requirement E3, reverberation, sound absorptiontechniques detailed in section 7 of the Approved Document shouldbe employed. BRE’s Acoustics Centre, funded by the DfES hasdeveloped an Excel spreadsheet to help designers carry outcalculations of facade insulation and reverberation times in rooms.The file can be downloaded fromwww.projects.bre.co.uk/envdiv/school_acoustics

To satisfy Requirement E4, refer to Building Bulletin 93 ‘AcousticDesign of Schools’ produced by the DfES and published by theStationery Office.

Because of the complexity of the design process, the documentstates, ‘In all but the simplest cases, it is advisable to appoint asuitably qualified acoustic consultant,’ who would normally be acorporate member of The Institute of Acoustics.

Table 8- Dwelling-houses and flats – performance standardsfor separating walls, separating floors and stairs that have aseparating function.

Airborne sound Impact soundinsulation insulation DnT,w + Ctr dB L’nT,w dB(Minimum values) (Maximum values)

Purpose built dwelling houses and flatsWalls 45 –Floors and stairs 45 62

Dwelling houses and flats formed by a material change of useWalls 43 –Floors and stairs 43 64

Table 9 - Rooms for residential purposes - performancestandards for separating walls, separating floors and stairsthat have a separating function.

Airborne sound Impact soundinsulation insulation DnT,w + Ctr dB L’nT,w dB(Minimum values) (Maximum values)

Purpose built rooms for residential purposesWalls 43 –Floors and stairs 45 62

Rooms for residential purposes formed by a material change of useWalls 43 –Floors and stairs 43 64

To satisfy Requirement E2, internal walls and floors must be built insuch a way that they achieve the sound insulation values fordwelling-houses, flats and rooms for residential purposes set out inTable 10 opposite, or to the minimum weight criteria as detailed inSection 5 of the Approved Document.


Table 11 – Housing Robust Detail applications not requiring Pre-Completion sound testing

Separating wall performance

E-WM-6

Airborne – dB mean 52

Airborne – dB range 48 - 56

E-WM-6 Finishes

Separating wall ≥600kg/m3 8kg/m2

Shield, Party Wall or plasterboardHi-Strength 7 on 8mm Hi-Strength 10 renderGeneral purpose scratch coatmortarType A wall ties

Inner Leaf ≥450kg/m3 8kg/m2

Turbo, Shield, plasterboardParty Wall or or 13mmHi-Strength 7 plasterHi-Strength 10Type A/B wall ties(Outer leaf brickwork)

For specific specifications, please refer to the Robust Details Ltd.Handbook.

46

Performance

100 10075

Table 12 – Flats Robust Detail applications not requiring Pre-Completion sound testing

Separating floor performance

E-FC-3 E-FC-4

Airborne – dB mean 52 51

Airborne – dB range 48 - 55 47 - 56

Impact – dB mean 52 55

Impact – dB range 44 - 59 51 - 60

E-FC-3 and E-FC-4 Finishes

Separating wall Non-Thermalite Robust As definedDetail solutions E-WM-1 by E-WM-1to 5 inclusive and E-WM-8 to 5 inclusive

and EWM-8

E-FC-3 E-FC-4

Flanking wallInner Leaf ≥600kg/m3 ≥450kg/m3 8kg/m2

Min. 100mm Min. 100mm plasterboardShield, Turbo, Shield, on dabsParty Wall or Party Wall or or 13mmHi-Strength 7 Hi-Strength 7 plasterHi-Strength 10 Hi-Strength 10(Outer leaf (Outer leaf (Outer leafbrickwork) brickwork) brickwork)

For specific specifications, please refer to the Robust Details Ltd.Handbook.

Sound insulation

Robust DetailsAs an alternative to Pre-Completion Testing in newdwelling-houses and flats, separating walls and floorsshall be designed and constructed as specified inRobust Details*.

These approved designs represent minimumperformance standards far superior to those in theApproved Document, and eliminate the need for Pre-Completion Testing.

The testing regime requires that these standards beachieved for each RD based on at least thirty tests, withnot more than eight of the tests on the same site, andinvolving more than one builder (to ensure a range ofworkmanship and supervision is covered).

The performance standards are in terms of the mean ofthe thirty tests, with no examples worse than thespecified individual value.

Robust Details and separating walls/floorsRobust Detail constructions are either separating wall orfloor constructions which have been assessed andapproved by Robust Details Ltd. to be capable ofconsistently exceeding the performance standards givenin Approved Document E of the Building Regulations.

The use of Robust Details for new build houses andflats provides an alternative to pre-completion testingfor demonstrating compliance with the performancestandards of Part E. Every dwelling built using RobustDetails needs to be registered with Robust Details Ltd.and a plot registration fee paid. Full details of thescheme and how to apply is available on:

www.robustdetails.com

There are two Robust Details for houses that allow compliance with Approved Document E:

E-WM-6 Cavity Separating Wall using general purposemortar.

There are two Robust Details for flats using Thermalitein the inner leaf of external walls that allow compliancewith Approved Document E:

E-FC-3 Precast concrete plank with screed laid onresilient layers. E-FC-4 Precast concrete plank with screed laid onThermal Economics IsoSonic Basefloor.

100 10075

100 10075

100 10075

100 10075


100 10075

100 10075

100 10075

100 10075

150 15075

215

215

47

Table 13 – Wall solutions using Thermalite requiring Pre-Completion Testing

Separating wall type Wall finishes External wall Authority Houses Flats with Rooms for inner leaf separating residential block type floor purposes

PCT1 Cavity 13mm plaster or 8kg/m2 ≥100mm Turbo BBA Yes No – Yes2 leaves 100mm Party Wall and 75mm cavity, plasterboard on dabs insufficient type ‘A’ wall ties data

PCT2 Cavity† 8mm sand/cement ≥100mm Turbo Thermalite Yes No - Yes2 leaves 100mm thin layer mortar, parge coat insufficient type ‘A’ wall ties 8kg/m2 plasterboard on data600-800kg/m3 block dabsApproved wall ties*

PCT3 Cavity 9kg/m2 plasterboard ≥100mm Shield BRE sound test Yes No – Yes2 leaves 100mm Shield and 75mm cavity, on dabs insufficient type ‘A’ wall ties data

PCT4 Cavity 13mm plaster or 10 kg/m2 ≥100mm Shield AD E Type 2.4 Yes No – Yes2 leaves 100mm Party Wall and 75mm cavity, plasterboard on dabs insufficient type ‘A’ wall ties data

PCT5 Cavity 13mm plaster or 10kg/m2 ≥150mm AD E 120kg/m3 N/A Yes Yes2 leaves 150mm Hi-Strength 7 and 75mm cavity, plasterboard on dabs Hi-Strength 7 wall masstype ‘A’ wall ties

PCT6 Solid 13mm plaster ≥100mm BBA No N/A Yes215mm Party Wall Turbo

PCT7 Solid 13mm plaster ≥150mm Thermalite/AIRO No N/A Yes215mm Hi-Strength 7 Hi-Strength 7

PCT8 Cavity 13mm plaster or 10kg/m2 ≥100mm Turbo AD E Wall types Yes No YesAggregate plasterboard on dabs 2.1 and 2.3

PCT9 Cavity 13mm plaster or 10kg/m2 ≥150mm AD E Wall type Yes Yes YesAggregate plasterboard on dabs Hi-Strength 7 2.2

PCT10 Solid 13mm plaster or 10kg/m2 ≥100mm Turbo AD E Wall type 1 Yes No YesAggregate with windows on both sides plasterboard on dabs

PCT11 Solid 13mm plaster or 10kg/m2 ≥150mm AD E Wall type 1 Yes Yes YesAggregate without windows plasterboard on dabs Hi-Strength 7

Note: This table is a simplified interpretation, omitting minimum mass requirements for partitions, where applicable. Always refer to Approved Document E or the Building Control Authority for confirmation and/or approval BEFORE commencing construction.*Where there is a structural requirement for wall ties, advice should be sought from Hanson’s Product Services department on tie suitability and Pre-Completion Testing.† Formerly Robust Detail E-WM-7.


48

Performance

Sound insulation

Internal walls Approved Document E requires that sound insulation performance for internal walls, for all residential buildingtypes, meets the level of 40Rw dB. Site testing is notapplicable. The insulation value for masonry walls maybe met by providing a laboratory test certificate, or byfollowing the guidance constructions shown in Table 14.

Table 14 – Guidance constructions for internal walls

Mass per unit area 90kg/m2 75kg/m2

Wall finish Plaster Plasterboardboth sides (lightweight) (12.5mm)

Thermalite block 100mm Shield 100mm Turbo(minimum) 75mm Shield

Internal walls which are loadbearing or connected to aseparating floor, should have a mass per unit area of atleast 120kg/m2, excluding finish.

Test Certificate AIRO L/2794 for 100mm Shield withplaster or plasterboard finish indicates compliance withthe 40Rw dB level.

100mm Shield partition

W.C

Dining room

Brick outer leaf

Internal floorsApproved Document E requires that airborne sound insulation performance for internal floors, for allresidential building types, meets the level of 40Rw dB.Site testing is not applicable.

Beam and block construction may be used for which Test Certificate AIRO L/2793 for 100mm Floorblockindicates compliance with the 40Rw dB level.

Table 15 – Thermalite in schools

AIRO No. Construction Rw

L/2794/2 Shield 100mm solid drylined 42

L/2794/3 Shield 100mm solid plastered 40

L/2674/1 Party Wall 215mm *t/l solid drylined 48

L/2674/2 Party Wall 215mm *t/l solid plastered 51

L/2674/3 Party Wall 215mm solid drylined 48

L/2674/4 Party Wall 215mm solid plastered 51

L/2674/A1 Party Wall 275mm t/l* cavity drylined 59

L/2674/A2 Party Wall 275mm t/l* cavity plastered 60

L/2674/A3 Party Wall 275mm cavity drylined 57

L/2674/A4 Party Wall 275mm cavity plastered 56

L/2751/1 Hi-Strength 7 215mm solid drylined 49

L/2751/2 Hi-Strength 7 215mm solid render/skim 54

L2889/1 Hi-Strength 7 215mm solid fair face 51

L2889/2 Hi-Strength 7 215mm solid dryline/Triline 58

L2889/3 Hi-Strength 7 215mm solid dryline/Gypliner 61

L2889/4 Hi-Strength 7 215mm solid render/gypliner 62

* t/l = Thermalite Thin Layer Mortar

Thermalite in schoolsTo satisfy Requirement E4, refer to Building Bulletin 93‘The Acoustic Design of Schools’ produced by the DfESand published by the Stationery Office. See also:

http://www.teachernet.gov.uk/acoustics

Because of the complexity of the design process, the document states, ‘In all but the simplest cases, it isadvisable to appoint a suitably qualified acousticconsultant’, who would normally be a corporate memberof The Institute of Acoustics (www.ioa.org.uk).

Thermalite offers the ability to construct a variety ofmasonry solutions for educational buildings to satisfythe performance levels required.

Unlike the performance standards for dwellings, the Ctr

(the correction to a sound insulation quantity) spectrumadaptation value is not used to define sound insulationperformance in schools.

Thermalite offers traditional single leaf solutions up to 54Rw dB cavity solutions up to 60Rw dB andspecifications combining with other materials up to 62Rw dB. Authority is by independent laboratory testcertificates.


49

Single leaf partition wallsSound reduction values for single leaf Thermalite wallsgiven in Table 16 below, have been derived from theautoclaved aerated concrete mass law for single leafwalls based on measurements made in accordance withBS 2750: Part 3.

(Luckin, K.R., Jones, A.J. and Engledow, G. (1989)‘Sound insulation performance of autoclaved aeratedconcrete’. Proceedings of the British Masonry Society,No 2.

R = 22.9 log (m) – 4.2dB, where m = erected wall mass.

Table 16 – Average sound reduction index R (dB) for single leaf walls

Block type Unfinished Dense Lightweight PlasterboardPlaster (1) plaster (2) on dabs

(12.5mm) (3)

Turbo

100mm 36.1 42.1 39.3 40.0

115mm 37.5 42.9 40.3 41.0

215mm 43.7 47.0 45.3 45.7

265mm 45.8 48.5 47.1 47.5

Shield

100mm 38.0 43.2 40.8 41.4

150mm 42.1 45.8 44.0 44.4

300mm 49.0 51.0 50.0 50.2

Party Wall

100mm 38.8 43.7 41.4 42.0

215mm 46.4 49.0 47.7 48.0

Hi-Strength 7

100mm 39.7 44.2 42.0 42.6

150mm 43.7 47.0 45.3 45.7

215mm 47.3 48.7 48.5 48.7

300mm 50.6 52.4 51.5 51.7

(1) 24.0kg/m2 has been added to the erected Thermalite wall weight for each side of 2 coat dense plaster.

(2) 11.0kg/m2 has been added to the erected Thermalite wall weight for each side of 2 coat lightweight plaster.

(3) 14.0kg/m2 has been added to the erected Thermalite wall weight for each side of 12.5mm plasterboard.

Table 17 – Weighted sound reduction values of constructions using Thermalite material

Independent Laboratory results by AIRO

Test ReportNo. & date Material Value

Partition tests (December 2001)

L/2794/2 Shield dry lined 100mm partition 42Rw dB

L/2794/3 Shield lightweight gypsum plaster100mm partition 40Rw dB

Hi-Strength 7 separating wall tests (February 2001)

L/2751/1 Separating wall 215 Hi-Strength 7dry lined 49Rw dB

L/2751/2 Separating wall 215 Hi-Strength 7render and skim 54Rw dB

Mortar comparison tests for cavity separating walls (October 1999)

L/2674/A/1 Cavity separating wall drylinedthin layer mortar 59Rw dB

L/2674/A/2 Cavity separating wall denseplaster thin layer mortar 60Rw dB

L/2674/A/3 Cavity separating wall drylinedgeneral use mortar 57Rw dB

L/2674/A/4 Cavity separating wall denseplaster general use mortar 56Rw dB

Laboratory aperture test results for single leaf walls areshown in Table 17.


50

Performance

Moisture penetrationAll Thermalite products, because of their closed cell structure,provide good resistance to the passage of moisture. Independenttests have indicated that Thermalite blocks make water penetrationextremely difficult.

0

20

40

60

80

100

2010 30 40 50 60 70

Time - Hours

Wet

are

a %

100mm thick aggregate block wall

100mm thick Thermalite block wall

Walls which contain an insulating material with thecapacity to store heat, such as Thermalite blocks, canhelp reduce condensation, because the temperaturedrop across the wall is gradual.

Vapour resistivityThe vapour resistivity of Thermalite is 60MNs/gm.

Moisture penetrationBoth single leaf and cavity masonry walls of various configurations will resist moisture penetration ifcorrectly designed, specified, and constructed usingproper standards of workmanship as defined in Annex Aof BS 5628: Part 3 and BS 8000: Part 3.

Cavity wallsCavity walls with a minimum outer leaf thickness will perform acceptably in all Exposure Zones, (see Table18, and map opposite.) Thermalite is commonly used aseither the inner leaf to a brick outer leaf separated by acavity, or as two separate leaves, finished externally witha moisture resistant or impervious cladding. A cavity wallwith a rendered outer leaf of 100mm Shield will performacceptably in zones of Very Severe exposure. Generally,a 50mm cavity is satisfactory, but consideration shouldbe given to wider cavities in conditions of Severe orVery Severe exposure.

Single leaf wallsThermalite is suitable for external solid walls, finished externally with a moisture resistant or imperviouscladding (see Table 19). To provide a weatherproof wallresistant to rain penetration, an appropriate externalfinish will be necessary, selected by reference to localexposure conditions as described in BRE Report 262 -Thermal insulation: avoiding risks.

Application of insulationEnhanced levels of insulation required by BuildingRegulations increase the risk of moisture penetration, ifcorrect standards of specification, application andconstruction are not applied. The simplified Table 20indicates recommended wall constructions for insulatedmasonry walls.

Time scale for water penetration – in terms ofpercentage wetted area

Table 18 – exposure zones

Zone Description Quantity of wind drivenrain litres/m2/spell*

1 Sheltered Less than 33

2 Moderate 33 to less than 56.5

3 Severe 56.5 to less than 100

4 Very severe 100 or more

* Maximum wall spell index with reference to BS 8104

Table 19 – recommended thicknesses of single leaf masonry–for different finishes and exposure zones. For walls up to 12m high.

Minimum block Un-rendered Rendered External Imperviousthickness (mm) as BS 5262 insulation cladding*

90 No Sheltered Severe Very severe

190 No Moderate Severe Very severe

215 Sheltered Severe Severe Very severe

440 Moderate Severe Severe Very severe

* Impervious cladding, as described in BS 5628 : Part 3, including slates, tile hanging, shingles, timber boarding or sheeting

Table 20 – Maximum recommended exposure zones(See Table 18) for insulated masonry walls

Insulation Built-in Injected full Injected Partial fill Internal type full fill (not UF full (UF insulation

foam) foam)

Cavity 75 100 75 100 75 100 50* 50 50width (mm) residual clear full fill

Wall typeimpervious cladding 4 4 4 4 4 4 4 4 4(full height)

Rendered finish 3 4 4 4 3 3 3 4 3(full height)

Facing masonry 2 3 2 3 1 2 2 3 2(tooled flush joints)

Refer to BRE Report 262 - Thermal insulation : avoiding risks for afull table of recommendations

Building Regulations for England & Wales, Scotland and NorthernIreland contain local requirements

* Partial fill cavities should maintain a minimum 50mm residual clear cavity width


51

York

Ripon

Darlington

Inverness

Dornoch

Lerwick

Aberdeen

DundeePerth

Stirling

Edinburgh

Dunbar

Glasgow

Ayr

Newcastle

AlstonWorkington

Carlisle

Hebden Bridge

Skelmersdale

Colwyn Bay

Stafford

Chester

Shrewsbury

NottinghamLincoln

Leicester

Birmingham

Manchester

Macclesfield

Sheffield

DoncasterGrimsby

Skegness

Hull

WhitbyMiddlesbrough

Norwich

Welwyn Garden City

Colchester

Northampton Cambridge

Peterborough

Swindon

Gloucester

Hay-on-Wye

Swansea

Cardiff

Brecon

Llandrindod Wells

Llanidloes

Bala

Bangor

BristolLONDON

Brighton

Aldershot Gatwick Dover

Eastbourne

Sidmouth PooleSouthampton

Exeter

Barnstaple Watchet

Weston-super-Mare

Newbury

Luton

Staines

Taunton

Londonderry

DungannonEnniskillen Belfast

Exposure zones Approx wind-driven rain*

(litres/m2 per spell)

1 Sheltered less than 33

2 Moderate 33 to less than 56.5

3 Severe 56.5 to less than 100

4 Very severe 100 or more

.

This map is an extract from ‘Thermal Insulation: avoiding risks’ and is reproduced with kind permission of the BRE.


52

Performance

Frost resistanceThe micro-cellular structure of Thermalite, incorporating millions of pocketsof trapped air, gives the material protection against the effects of frost.

Independent comparative frost resistance tests havebeen carried out on facing bricks, common bricks andThermalite blocks. After 20 freeze/thaw cycles, thefacing bricks were severely cracked. At 61 cycles, theThermalite blocks showed no signs of cracking.

This test was repeated with additional strength testsbeing carried out after 20, 40 and 60 cycles, and thisconfirmed that Thermalite has satisfactory frostresistance and that there is no reduction in strengthunder these conditions.

Table 21 – Compressive strength and freeze/thaw resistance(from blocks at each density)

0 cycles 20 cycles 40 cycles 60 cycles

Saturated cube strength(N/mm2) 4.67 4.94 5.37 5.45

Change on original Nil +15% +15% +16%

A similar test undertaken by the British Board ofAgrément (BBA) produced similar results.

Table 22 – Compressive strength and freeze/thaw resistance(from blocks at each density)

Nominal density As received After 60 cycles Increase(kg/m3) freeze/thaw

500 3.20 3.25 +1%

600 3.85 4.10 +6%

730 5.80 6.00 +3%

The inherent frost resistance of Thermalite blocksmeans that all products within the range are suited foruse below d.p.c level. The data shown is confirmed bylaboratory tests carried out to draft European TestMethods (undergoing development at time of writing).The mortar properties should be appropriate to thedegree of frost resistance required.


53

4 Design detailingFoundations 54

Floors 56

External walls 57

Partitions 61

Separating walls 63

Reveals 64

Movement control 65

Structural use 69


Design detailing

Trenchblock | Hi-Strength Trenchblock | Hi-Strength 7 | Hi-Strength 10 | Shield | Turbo | Party Wall

Foundations

ApplicationsIn addition to Thermalite Trenchblock and Hi-StrengthTrenchblock, Hi-Strength 7, Party Wall and Shield blocks can also be used as foundation blocks where soil andgroundwater conditions prevail up to and includingClass DS4 sulfate levels, and Turbo blocks in conditionsof Class DS3, both as defined in Table 2 of BRESpecial Digest 1.

Typical detailsThe following typical details illustrate the proper use ofThermalite blocks below d.p.c. level, and may not be applicable to other manufacturers’ materials.

Thermal insulationFoundation walls constructed of Thermalite Trenchblock provide a high level of thermal resistance. As aconsequence, no cold bridging occurs at theintersection of the insulated external wall, the groundfloor and the foundation wall. See details 1 and 2 below.

Thermalite Trenchblock and Hi-Strength Trenchblock are ideal blocks forfoundation walling below d.p.c level. They combine lightweight constructionwith added insulation and, as no cavity infill is required, Trenchblocks providea saving in both construction time and cost. Other Thermalite blocks mayalso be used.

Detail 2. Solid external wall with external insulation and insulation above floorslab - typical section through foundations

d.p.c

Ground level

Trenchblock

Insulation above slab

Thermalite solidexternal wall

Insulated claddingwith rendered finish

d.p.m

The ‘Robust Construction Details’ and the BRE Report‘Thermal insulation: avoiding risks’, published along with the latest revision of the Building Regulations, illustrate the use of aircrete in foundation walls as a way oflimiting thermal bridging and thereby satisfying thethermal insulation requirements of the appropriateregulations.

Thermalite Trenchblock foundation walls can alsoenhance the U-Value of ground floors and reduce theneed for additional insulation in the floor construction,making them a cost-effective way of complying with theappropriate regulations.

Concrete floor slab edge insulationThe ‘Robust Construction Details’ document requiresedge insulation of the slab if the inner leaf fails toachieve a thermal resistance (R) of 0.75m2.K/W. This can be achieved by 100mm or thicker Turbo blocks.For all other non-aircrete block types, additional slabedge insulation will be necessary.

Detail 1. Brick/block external wall with partial fill cavity insulation and insulationbelow floor slab - typical section through foundations

Thermaliteinner leaf

d.p.c

d.p.m

d.p.c

Ground level

Facing brick

Trenchblock

Perimeter insulation

Insulation below slab

Partial fillcavity insulation

54


55

Detail 6. Cavity party wall - typical section through foundationsDetail 5. Internal partition - typical section through foundations

Detail 4. Brick/block cavity wall with timber suspended ground floor –typical section through foundations

Detail 3. Timber frame construction with timber suspended ground floor –typical section through foundations

Thermaliteparty wall

Concreteground floor

d.p.c d.p.m

Thermalitepartition

d.p.c

Concrete ground floor

d.p.m

Insulated timberfloor

d.p.c

Ground level

Facing brick


Trenchblock

Insulated timber frame

Insulated timber floor

Painted brick

Render

Trenchblock

d.p.c

Thermaliteouter leaf


56

Design detailing

FloorsFloorblock | Floor Endblock | Coursing Slips

ApplicationsThermalite Floorblock is suitable for both domesticprojects and, with floor beams at closer centres, mayalso be used in non-domestic applications. For furtherinformation, please contact Hanson’s Product ServicesDepartment.

Floors built with Thermalite Floorblock will meet thestructural requirements of the Building Regulations,provided that the floor loadspans are calculated inaccordance with BS 8110: Part 1, and the Floorblocksare specified and installed in accordance with AgrémentCertificate No 91/2723.

InstallationAfter the Floorblocks have been positioned, before anytrafficking or loading is allowed, and before any floorfinish is commenced, it is recommended that the floorbe grouted with a 1:4 cement/sharp sand composition.

Thermalite Floorblock, together with Floor Endblocks and Coursing Slips, forms a complete insulated flooring system for use with any proprietaryinverted T-beam structure.

Detail 8. Brick/block cavity wall with inverted T-beams and Floorblocks – typical section through perimeter wall showing Coursing Slips

Partial fill cavityinsulation Floorblock

d.p.c

Insulated timber floor

Trenchblock


ScreedingThe floor screed should be 1:3 cement/sand inaccordance with BS 8204: Part 1. The minimum depthrecommended for domestic ground floors is 50mm.

For non-domestic applications, a minimum 50mm thickconcrete screed with a minimum compressive strengthof 20N/mm2 should be specified. The manufacturers ofthe floor beams should be consulted with regard tobeam spacing and the possible need for reinforcementto the screed.

The cement/sand screed can be laid directly on the grouted floor and, unless it is particularly moisture-sensitive, a damp-proof membrane need not be laid overthe grouted pre-cast floor.

Floating layersFloating layers, such as timber boarding on battens,including insulation, may be laid over the groutedFloorblocks.

Detail 7. Typical edge detail of inverted T-beam and Floorblock system

Shield

d.p.c.

Endblock

Floorblock and Coursing Slips

Trenchblock

Facingbrick

Beams


57

External wallsTurbo | Shield | Hi-Strength 7 | Hi-Strength 10 | Party Wall | Paint Grade Smooth | Coursing Bricks

External wallsThe combination of moisture-resistance, strength andthermal insulation performance makes possible a widerange of external wall solutions for all types of buildingsfrom traditional dwellings to commercial/industrial units.

For two-storey dwellings, Thermalite Turbo and Shieldare normally more than adequate to satisfy thestructural requirements of the Building Regulations. The introduction of Thermalite Hi-Strength 7 and Hi-Strength 10, however, extends the range ofThermalite applications to include 3 and 4-storeyresidential buildings, as well as offices and othercommercial and industrial buildings.

The inherent thermal insulation characteristics of theThermalite product range also enable external wall constructions to meet the thermal insulationrequirements of the building regulations. PossibleThermalite solutions include cavity walls incorporatinginsulation material that partially or fully fills the cavity or,alternatively, cavity walls with insulating internal liningsystems.

External solid walls, which are growing in popularity, areanother method of meeting the requirements of thebuilding regulations. The external wall may be of solidThermalite alone or a combination of Thermalite andinternal or external insulation systems.

The construction of Thermalite blocks should be carriedout in accordance with BS 5628: Parts 1 and 3 and BS 5250, as well as the information contained in theBritish Board of Agrément certificate 00/3720.

LintelsThe external wall should be set out to ensure that theends of lintels bear onto full blocks, not onto cut piecesof block, and the length of the bearing should be atleast 150mm.

Situations will occur where the stress beneath the lintelbearing is likely to exceed the design stress. In suchcases either the lintel bearing area should be increasedor concrete padstones or spreader beams should bepositioned beneath the ends of the lintel.

One of the primary functions of external walls is to provide an efficientweathershield, by preventing the penetration of moisture, which can have adetrimental effect on the internal structure. The high moisture-resistantproperties of Thermalite aircrete blocks make them ideal for theconstruction of the inner and outer leaves of external cavity walls, as wellas solid external walls.

The use of lintels can introduce thermal bridging. It is therefore recommended that the lintel eitherincorporates insulation material or be of a type thatallows Thermalite blocks to be included as part of the lintel.

Wall tiesIt is important that the correct type of cavity wall tie isselected. The wall ties most suitable for use withThermalite are those that will transmit axial loadbetween the leaves of the cavity wall, but at the sametime be sufficiently flexible to allow differentialmovement to take place between the two leaves.

Wall tiles should either comply with DD140 or BS EN845-1 and should be made of material as references 1 or 3 in BS EN 845 Table A1, austenitic stainlesssteel. To satisfy the requirements of ApprovedDocument A, ‘Structure’, wall tiles should be selected inaccordance with Table 5 of that document.

In external cavity walls the wall ties should be beddedinto each leaf to a minimum depth of 50mm. The spacing of wall ties should be as given in thefollowing table reproduced from BS 5628: Part 3:

Additional ties to those shown in the table above should be provided at not more than 300mm vertical centres:

1. Within 225mm of vertical edges of openings

2. Within 225mm of other vertical unrestrained edges (i.e. movement joints)

3. At sloping unrestrained edges (i.e. sloping roof verges)

4. In narrow piers between openings.

Least leaf Cavity Equivalent Approximate spacing of tiesthickness width no. of ties Horizontal Vertical(one or both) (mm) per m2 (mm) (mm)

65 - 90mm 50 - 75 4.9 450 450

≥ 90mm 50 - 300 2.5 900 450


58

External walls

Design detailing

Elimination of thermal bridgingThe requirements of the Building Regulations placeparticular importance on the elimination of thermalbridging, such as can occur around openings, at thejunction between external walls and floors and at eaveslevel. The BRE Report ‘Thermal insulation: avoidingrisks’, discourages the use of clay bricks over otherdense materials. The report does, however, activelyencourage the use of low density blocks such asThermalite as a satisfactory means of reducing thermalbridges.

The continuous use of Thermalite blocks, together withThermalite Coursing Bricks, across junctions with floors,will reduce thermal bridging.

See also BRE IP 17/01 ‘Assessing the effects ofthermal bridging at junctions and around openings’.†

InstallationThermalite blocks are suitable for the construction ofexternal cavity and solid walls, when installed inaccordance with the relevant Detail Sheet of AgrémentCertificate 00/3720. The walls should be designed andconstructed in accordance with the recommendations ofBS 5628: Part 1, BS 5628: Part 3 and BS 5250.

In addition, the table below gives minimum thicknessesof blocks in solid rendered walls related to exposureconditions as defined in BS 5628: Part 3 and BS EN1996-1-1 (Eurocode 6).

Table 23 – Thickness of rendered Thermalite solid walls for various exposure conditions

Exposure Minimum block thickness (mm)

Severe 215

Moderate / severe 190

Sheltered / moderate 140

Sheltered 90

Very sheltered 90

For further information on resistance to moisture penetration, seepages 50 and 51.

Table 24 – BS 5628-3 describes exposure categories for wind driven rain

Exposure category Wall construction

3 – Severe 215mm Thermalite blocks rendered to BS EN 13914-1

4 – Very severe Solid wall with impervious cladding

Solid wallsThermalite is an ideal material for the construction of extensions to existing properties, with a range of blocksizes and strengths that offer choice of structuralperformance, external appearance and internal finish.

Solid wall construction is also viable for the design ofcomplete houses and other buildings, fully in compliancewith Building Regulations and Standards, especiallywhen associated with thin layer mortar. High levels ofinsulation can be achieved and advantage can be takenof the thermal mass to assist with heat retention inwinter and cooling in summer.

Render is a traditional external finish in many parts ofthe UK, and is easily applied to Thermalite solid walls togive a wall with excellent resistance to waterpenetration by wind driven rain (see Table 24).

In addition to traditional and technical renders,Thermalite will readily accept a range of imperviouscladdings fixed with either mechanical fasteners oradhesives such as:

• timber weatherboard• tile hanging • manufactured board cladding• insulated render systems• ceramic tiles• brick slip systems

The ease with which the material can be worked on siteby cutting or chasing, allows for easy adaptation ofdetailing to accept standard construction accessoriessuch as lintels, restraints and weathering materials.

* See page 12†No longer current, but cited in Building Regulations.


59

Detail 9. Brick/block external wall with full-fill cavity insulation and flat roof – typical eaves, window and floor details

Timber floor

Sound insulating quilt

Full-fill cavity insulation

Full-fill cavity insulation batt

Full-fill cavity insulation

Facing brick



60

External walls

Design detailing

Detail 11. Brick/block external wall with partial fill cavity insulation, pitched roof and ventilated loft – typical eaves, window and floor details


Concrete floor

Insulation

Partial fill cavity insulation batt

Calcium silicate board

Loft insulation to meetcavity insulation

Detail 10. External solid wall in thin joint masonry with externalinsulation and brick slips – typical detail

Loft insulationto meet externalinsulation

Concrete floor

Brick slipson externalinsulation

Over-fasciaventilation strip

Insulated lintel

Thermalite solidexternal wall


61

Partitions Turbo | Shield | Party Wall | Hi-Strength 7 | Hi-Strength 10 | Paint Grade Smooth | Coursing Bricks

Steel angles or timber battens to provide lateral resistance

Sheet of polythene at base of wall turned up at sides and lightly nailed. Trimmed off after screed sets

20mm compressiblematerial

Masonry grade bedjoint reinforcementincluded in bottomtwo horizontalmortar joints

Floor screed

Beam or floor

ApplicationsThermalite Turbo, Shield, Party Wall, Hi-Strength andPaint Grade Smooth blocks are suitable for theconstruction of internal partition walls above and belowd.p.c. level. To meet the requirements of ApprovedDocument E, ‘internal wall type D’, a plasterboard finishwill need to be applied to both sides.

Typical detailsUnless they are designed as free-standing walls,internal partitions should always be restrained bycontinuous or intermittent horizontal or vertical supports,

When used to construct partitions, Thermalite blocks reduce soundtransmission between rooms and provide a secure fixing for shelves,radiators and other fittings.

Detail 13. Joint between non-loadbearing partition and soffit of floor

or roof subject to small deflection or thermal movement

Detail 12. Non-loadbearing partition between beams or floors subject

to large deflection

Joint temporarily wedged forstability and filled with softmortar. Hard, dense materialor strong mortar must not beused. Remove wedges beforeplastering. Sever render andfinishing coat with tip of floatat intersection of soffit and wall

13mm gap

Plaster

Roof or floor

similar to those shown in Details 12 and 13 below. The lengths and heights of the walls should be withinthe limits quoted in tables 25 and 26 on page 62.

Non-loadbearing walls and partitions(unplastered)Tables 25 and 26 are based on BS 5628: Part 3.(Plaster finishes tend to increase the stability of a wall.)For advice on free-standing walls, please consultHanson’s Product Services department.


62

Partitions

Design detailing

Table 25 – Recommended block width (mm) for walls restrained at both ends and the top

Height of wall Length of wall (m)(m) 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0

2.3 75 75 75 75 75 90 90 90 90

2.4 – 2.6 75 75 75 75 90 90 90 90 90

2.7 75 75 75 90 90 90 90 90 90

2.8 – 3.0 75 75 75 90 90 90 100 100 100

3.1 – 3.3 75 75 90 90 90 100 100 115 115

3.4 – 3.5 75 90 90 90 100 100 125 125 125

4.0 90 90 90 100 100 140 140 140 140

4.5 90 100 100 140 140 140 140 140 140

5.0 100 100 125 140 140 140 140 140 140

5.5 100 125 140 140 140 140 140 140 150

6.0 100 125 140 140 140 140 140 150 150

Table 26 – Recommended block width (mm) for walls restrained at both ends but not the top

Height of wall Length of wall (m)(m) 2.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0

2.3 75 90 100 140 140 140 190 190 190 200

2.6 75 90 100 140 140 140 190 190 190 200

2.7 75 90 100 140 140 150 190 190 190 200

3.0 75 90 100 140 140 150 190 190 190 215

3.3 75 90 100 140 140 150 190 190 190 215

3.5 75 90 140 140 140 150 190 190 200 215

4.0 75 100 140 140 140 190 190 190 200 215

4.5 75 100 140 140 140 190 190 190 200 215

5.0 75 100 140 140 150 190 190 190 215 255

5.5 75 115 140 140 150 190 190 200 215 255

6.0 75 115 140 140 150 190 190 200 215 255

Table 27 – Recommended block width (mm) for walls restrained at the top only

Maximum height (m) 2.25 2.7 3.0 4.2 4.5 5.7 6.0 6.45

Block thickness (mm) 75 90 100 140 150 190 200 215


63

Separating wallsParty Wall | Shield | Hi-Strength 7 | Hi-Strength 10

mm Party Wall Shield/Strength 7 only

75mm cavity

Concrete floor

Plaster finish

ApplicationsThermalite Party Wall, Shield, Hi-Strength 7 and Hi-Strength 10 blocks can be used in all types of soundinsulating separating walls between dwellings.

Thermalite blocks have been independently tested and proven for use inthe construction of sound insulating walls between dwellings.

Detail 15. Section through cavity party wall with timber suspended floorsDetail 14. Section through cavity party wall with concrete suspended floors

100mm Party Wall Shield/Hi - Strength 7 only

75mm cavity

Joist hanger

Timber floor

Soundinsulation quilt

Plaster finish

Sound insulationDesigners and specifiers should ensure that allseparating wall details meet the sound insulationrequirements of the Building Regulations, and also thatapproval is obtained prior to commencing construction.

If advice is required on meeting the requirements of Approved Document E with Thermalite blocks, please contact Hanson’s Product Services department.

For further information on Sound InsulationPerformance, see pages 44-49.


64

Design detailing

Reveals


d.p.m

Thermalite of suitable depthor proprietary cavity closer

To meet the thermal insulation requirements, the thermalresistance (R) of the cavity closer should be minimum0.45m2K/W. The following minimum depths of cutThermalite (excluding mortar), of width matching that ofthe inner leaf block, will comply with this figure:

• Turbo: 50mm

• Shield: 68mm

• Party Wall: 72mm

Detail 17. Window frame overlapping cavity closer – rebated reveal for very severeexposure zones

Detail 16. Window frame overlapping cavity closer – flush reveal

d.p.m

Thermalite of suitable depth

• Hi-Strength 7: 86mm

See also BRE IP 17/01 ‘Assessing the effects ofthermal bridging at junctions and around openings’.

The window frame should overlap the closer block by minimum 30mm, (see detail 16 below).

In very severe exposure zones, the masonry should berebated, (see detail 17 below).

Note: The information contained in this section may be subject to change dueto the on-going re-drafting of Accredited Details/BRE Best Practice Guide.


65

Movement control

ties in alternate courses

Movement in masonry wallsAll masonry walls are subject to movement, which canbe caused when the walls dry out, as a result of cyclesof heating and cooling or from changes in moisturecontent. If provisions are not made to allow movementwithout restraint, then there can be a build-up ofcompressive or tensile forces that may cause themasonry to bow or crack.

It is important that at the design stage the designer recognises the factors that may affect a building’s performance and makes provisions to accommodate any likely movement.

To aid the designer, along with the information in this section of the manual, there is detailed information in BS 5628: Part 3 on movement in masonry and its accommodation.

In concrete masonry walls, including Thermalite walls,the movement that occurs is primarily a consequence ofmoisture movement whilst drying out (shrinkage) andtherefore, it is normally only necessary to accommodatethis movement in simple construction joints.

Positioning movement jointsWhen positioning movement joints at the design stage itis essential that the designer ensures that the locationsof the joints do not impair the stability of the walls inwhich they occur.

It is particularly important to provide movement joints inthe long runs of walls that occur in commercial andindustrial buildings as well as in large residentialbuildings. It is also important to provide movement jointsin solid external walls and the outer leaves of externalwalls that are subject not only to drying out movement,but also to changes in temperature and moisturecontent.

The inner leaves and internal walls of traditionaldwellings do not normally require movement joints, andthe use of bed joint reinforcement at openings is usuallysufficient to avoid the risk of movement cracks, (seeDetail 27, page 68).

Following the guidance in BS 5628: Part 3, movementjoints should be provided at 6.0m centres to divide upthe walls into a series of rectangular panels. Where thewall is continuous at an internal or external corner, thefirst movement joint should be approximately 3.0m fromthe corner, (see Detail 18, top right).

The risk of movement cracking increases where thelength of the wall panel exceeds twice the height, forexample, in low horizontal panels beneath continuouswindow openings. In such cases it is advisable toprovide movement joints at closer centres than thenominal 6 metres.

When positioning movement joints, the followingfeatures, which may influence the movement jointlocations, should be taken into account:

• intersections of walls, piers and columns• positions of doors and window openings• changes in height and thickness of walls• locations of chases in walls• locations of structural movement joints in the building• positions where dissimilar materials meet

Lateral restraintWhere the design criteria require continuity across themovement joint, whilst still allowing horizontalmovement, flat metal strips measuring 200 x 25 x 3mmor similar should be built into alternate bed joints,spanning the movement joint. One end of each metalstrip should be debonded by wrapping in polythene orbuilding paper to ensure free movement. Proprietarymovement joints with one end sleeved are alsoavailable.

Wall finishesAll wall finishes should be discontinued at movementjoints. In the case of plaster and render finishes.proprietary metal stop beads should be used on eachside of movement joints.

Where ceramic wall tiling is to be fixed to the finishedwall, the movement joints should be continued throughthe tiled finish. BS 5385: Part 1 recommends that largetiled areas be divided up into panels with movementjoints at 3.0 to 4.5m centres.

Detail 18. Location of movement joints


66

Movement control

Design detailing

D ti l b tt j i t

Debonded movement jointties in alternate courses

Detail 19. Dry movement joint in internal blockworkDetail 22. Junction of internal partitions

ServicesAny services or other fittings that are required to spanthe movement joints should be designed to allow formovement.

Dissimilar movementWhere Thermalite block walls join with other materials,such as brickwork, other concrete blockwork, structuralsteel or concrete etc, differential movement will occur.To allow such movement to take place, a verticalmovement joint should be provided to separate thedifferent materials.

Where dissimilar materials bear onto Thermalite walls,such as insitu concrete floors, pre-cast beams or floorunits etc., a separating layer should be introduced usinga non-compressible material such as a bituminous dampproof course.

Construction of movement jointsMovement joints should be built in as work proceeds. The simplest form of movement joint is a vertical buttjoint; this can be dry (Detail 19), or filled with acompressible joint filler. In the case of an external wall

Detail 20. Sealed movement joint in external blockwork

sealant or strip Debonded movement jointties in alternate courses

Detail 21. Movement joint in fire wall

600

0mm

mPlaster or render


Detail 23. Junction of partition and inner leaf of external wall

300

0mm

max

Mastic sealant

Render finish

Square-nosed plaster stop bead

External blockwork

Compressible sealer


the joint will need to be sealed to prevent the ingress ofmoisture. The blockwork should be rendered to parallelsquare-nosed stop beads and the movement jointsealed with a proprietary mastic sealant (Detail 20). The selection and use of all sealants should be in accordance with BS 6213 and BS 5628: Part 3.

Movement joints in fire walls should be designed so that the ability of the wall to function as a fire barrier is notimpaired. This is generally achieved by sealing the joint filler with intumescent sealant or strip (Detail 21).

Junctions of internal wallsWhere movement has to be allowed for at junctions of internal walls, the movement joints may be incorporatedinto either or both of the walls (Details 22 and 23).


67

10mm dry joint or compressible filler

6000mm max6000mm max

Debonded movementjoint ties

Galvanized flat tie in abbey typeslot at alternate courses

6000mm max6000mm max

Reinforced concrete column

ORDebonded movementjoint ties

mentjoint ties

Detail 26. Blockwork fire protection of structural steel column with movement joints

Junctions with structural membersWhere blockwork is tied to a structural steel orreinforced concrete column, the design of the jointshould allow for any movement that may occur in thestructural member (Details 24 and 25).

The Thermalite blockwork should be tied to the columnswith 100mm x 100mm angles of 25mm x 3mm flatsteel strip, fixed to the columns and built into alternatehorizontal movement joints. Alternatively, proprietary tiesmay be used. It is advisable to debond the flat strip inthe mortar joints.

Movement should be accommodated with debondingties at both ends of a masonry panel (e.g. betweencolumns).

Detail 24. Junction with structural steel column

Detail 25. Junction with reinforced concrete column

Fire protection of columnsWhere blockwork is used to provide fire protection tocolumns, movement joints can be incorporated into theblockwork casing (Detail 26).


68

Movement control

Design details

Bed joint reinforcementIn walls containing openings, movement joints may needto be provided at more frequent centres than 6 metres.Alternatively, the masonry above and below the openingshould be reinforced with masonry grade bed jointreinforcement (Detail 27).

The reinforcement should be contained in the horizontalmortar joints so that the mortar cover is 13mm on theface of the internal blockwork and 25mm on theexternal face. The reinforcement should extend at least600mm beyond each side of the opening to ensure thatany stresses are distributed into adjacent blockwork.In some instances, it may be appropriate to include bedjoint reinforcement in the mortar joints over the fulllength of the wall in such a way that movement joints,which would normally be recommended, may be omitted.An example would be separating walls, which should notcontain movement joints.

Bed joint reinforcement in two coursesbelow and/or above opening

Opening

600mm600mm

Detail 27. Bed joint reinforcement at opening

Mortar strengthThe strength of the mortar should be compatible withthe strength of the blocks. In accordance with thedefinitions in Table 13 of BS 5628: Part 3, mortardesignation (iii) should be used. For furtherinformation, please refer to page 76 of the Siteworksection.


69

Structural use

Structural designDwellings of up to 3 storeys

For residential buildings of up to 3 storeys, the BuildingRegulations, along with BS 8103: Part 2, provideguidance in the form of ‘simple rules’ to enable thedesigner to determine the required strength and wallthicknesses of masonry to be used without the need forstructural calculations.

Whilst the dimensions of the building layout willinfluence the strength and thickness of the masonry ingeneral, for residential buildings of up to 2 storeys acompressive strength of 2.9N/mm2 will meet the criteriaof the ‘simple rules’, and can be achieved using any ofthe Thermalite block products.

In the case of the upper two storeys of 3 storeyresidential buildings 2.9N/mm2 will meet the criteria,whilst at ground floor level and below d.p.c. the ‘simplerules’ require a compressive strength of 7.3N/mm2,which can be achieved by using Thermalite Hi-Strength 7. As an alternative to following the ‘simplerules’ guidance, the required thickness and compressivestrength of the masonry can be determined bycalculation, see ‘Other types of building’.

Other types of building

For residential buildings of over 3 storeys andcommercial and industrial buildings, the structuraldesign should be carried out in accordance with BS 5628: Part 1 by a suitably qualified engineer.

When carrying out the design in accordance with BS 5628: Part 1, the structural engineer will take intoaccount general factors when calculating the load theparticular wall will safely support. In respect of theThermalite product range the following information willbe required:

• the compressive strength of the product

• the partial safety factor for the material

Hi-Strength 10 and ‘Special Category’

All Thermalite blocks are manufactured to SpecialCategory of Manufacturing Control in accordance withBS EN 771-4 and BS 5628: Part 3. Therefore, γm = 3.1 can be used, if required in calculations. This applies to the 8.7N/mm2 Hi-Strength 10 materialthat can be shown by design calculation to provide anequivalent wall strength to 10.4N/mm2 concrete blocksmanufactured under the less onerous ‘normal category’conditions.

Thermalite blocks will provide an excellent structural solution for mostapplications.

For further advice on the structural design of Thermalitemasonry walls, contact Hanson’s Product Servicesdepartment.

Disproportionate collapse

Approved Document A 2004 contains importantrevisions to the application of Requirement A3,Disproportionate Collapse, to bring all buildings undercontrol. The guidance refers to 4 Building Classes thatare tabulated and described therein. In Class 1, forhouses not exceeding 4 storeys, agricultural buildings orbuildings into which people rarely go (subject toconditions), provided that they are designed andconstructed in accordance with the ‘simple rules’ orother Section 1 guidance, no additional measures arelikely to be necessary. Buildings in other classes will besubject to additional measures as described. A TechnicalGuidance Note has been produced by the NHBC inconsultation with the DCLG to supplement the guidancein Section 5 of the Approved Document.

Lateral restraint

The Thermalite block walls should be provided withadequate lateral restraint at floor and roof levels.Clauses 28.2 and Appendix C of BS 5628: Part 1provide detailed guidance on methods of restraint.

Joist hangers

The use of joist hangers to support timber floor joists isbecoming increasingly popular, particularly when thesupporting wall is a party wall. It is important that thejoist hangers used comply with BS EN 845-1 and aremarked with the minimum compressive strength of theblock with which they are to be used. The type and sizeof hanger should be selected to suit the span and thesize of the joist to be supported.

It is important to install the joist hanger with the backplate tight against the surface of the supporting walland in accordance with the manufacturer’s instructions.The masonry flanges and the joist hanger should beheld in position by sufficient masonry above the joisthanger support and should be allowed to achieveadequate strength before any load is applied to thehanger.


70

Structural use

Design detailing

Manufacture and testingThe European Standard BS EN 771-4 is the standardfor the specificaton of aircrete blocks. It addresses the essential requirements of theconstruction products directive and contains guidanceon CE marketing of products. This is reflected in theBuilding Regulations, Approved Document A, ‘Structure’(2004 and amendments), which contains tables ofminimum compressive strengths of masonry units. A revised BS 8103 was published early in 2005, whichreflects these circumstances.

The Thermalite product range provides compressivestrength that reflects both the regulatory requirementsand the need of the designer to satisfy the structuralrequirements of a wide range of building types.

Modulus of elasticityTypical values for the Modulus of Elasticity (E) ofThermalite blocks are as follows:

• Turbo: E = 1700N/mm2

• Shield: E = 2100N/mm2

• Floorblock: E = 2600N/mm2

• Party Wall: E = 2600N/mm2

• Hi-Strength 7: E = 2900N/mm2

• Hi-Strength 10: E = 3100N/mm2

Linear expansionThe co-efficient of linear expansion of all Thermaliteblocks is 8.0 x 10-6K-1.


71

5 SiteworkCDM Regulations 72

Health and safety 74

Mortar 76

Workability 78

Fixings 79

Internal finishes 82

External finishes 84


72

CDM Regulations – Construction (Design and Management)

Construction is one of Britain’s most hazardous industries, with back paincited as the single biggest cause of ill health. Musculo-skeletal disordersaffecting the back are a major injury cost to employers according to theHealth & Safety Executive (HSE). The HSE recommends improvements tohealth and safety standards during construction work. These include sitevisits to ensure the safe use of manual lifting techniques.

What are CDM regulations?The CDM Regulations, devised by the Health and SafetyExecutive, are designed to reduce serious or fatalaccidents and ill health in the construction industry byimproving management and co-ordination of health,safety and welfare throughout all stages of aconstruction project.

...there is no excuse for either ignorance orcomplacency. We have no hesitation in takingenforcement action against those who fail to take thenecessary action to control risks on site.” HSE

When do CDM regulations apply?The CDM Regulations place responsibility on allindividuals who can contribute to the health and safetyof a construction project.

In commercial, domestic and industrial projectsparticular attention must be paid to:

• Site clearance

• New build, alteration, conversion and fitting out

• Renovation and repair

• Maintenance

• Demolition

Block weightsThe Construction Industry Advisory Committee(CONIAC) advises that the handling of heavy buildingblocks can result in a wide range of injuries where thedamage is gradual and progressive over a substantialperiod of time.

The risk of injury is largely determined by the weight ofthe block – the heavier the block, the higher the risk ofinjury.

After taking account of expert opinion and the longhistory of complaints over handling heavy blocks,CONIAC has concluded that there is a high risk ofinjury in the single-handed, repetitive manual handling ofblocks heavier than 20kg.

If single person handling is needed, either blocks of “...20kg or lighter should be specified and used, or otherprecautions should be taken to reduce the risk of injuryby, for example, the provision of mechanical handling.”CONIAC

The Thermalite solutionThe Thermalite micro-cellular structure results in anunrivalled product range which is both strong andexceptionally light to handle. Indeed, standard sizeblocks are available in weights less than 20kg, inaccordance with guidelines.

“


7373

Variation in block weights Individual block weights cited in this manual are basedon a theoretical equilibrium value used for testing andcalculation purposes. Moisture content prior to use willbe higher than the quoted value and is variable subjectto date of manufacture prior to delivery, weather andstorage conditions.

The delivered weight format of the Thermalite productrange generally falls well below handling guideline limits.However, if there are specific manual handling concerns,particularly with larger block sizes, Hanson recommendssite sampling and weighing to determine safe handlingpractices.

Table 28 – Pattern for 3 day injuries as reported by the HSE

Handling of heavy dense building blocks can result in a wide range of injuries, where the damage is gradual and progressive over a substantial period of time.

Cause of injury Type of injury

Handling36.9%

Other 16.1%

Struck 15.9%

Trip 20.2%

Falls 6.5%

Machinery 4.4%

Back45%

Other 3%

Lower limb 9%

Arm 13%

Rest of torso 8%

Hand 6%

Finger/Thumb 16%

Table 29 – Block weights (for 215 x 440mm blocks)

Thermalite block @ 730kg/m3 (7.3N/mm2)

Thickness (mm) Weight (kg)

100 7.1

140 10.0

190 13.5

215 15.3

HandholdsThe HSE also recommends that blocks with handholdsshould be selected wherever possible. Thermalite is the first block manufacturer in the UK to offer handholds,which have been introduced in our Trenchblock range,to further aid the process of lifting and layingfoundations, making building with Thermalite not onlyfaster, but safer too.

WorkabilityThermalite blocks are not only easy to handle, they areextremely workable and can be easily cut, sawn andchased accurately with ordinary hand tools. The lightweight of Thermalite products, combined with their easyworkability, ensures significant productivity gains.

Notes• 7.3N/mm2 blocks are available in the Hi-Strength 7 and

Hi-Strength Paint Grade Smooth product ranges.• Block weights are calculated using specified dry density, with a

moisture content of 3% by weight added to provide the equilibrium value.


74

Sitework

74

Health and safetyThe Control of Substances Hazardous to Health Regulations (COSHH) requirements of the Health and Safety at Work Act, The ConsumerProtection Act and The Chemicals (Hazard Information and Packaging forSupply) Regulations, require us to provide relevant information regardingour products in respect of their properties, correct use, storage/handlingand disposal without risk to health. (A separate COSHH data sheet isavailable for thin layer mortar).

ProductsAutoclaved aerated concrete building blocks.

CompositionPulverised fuel ash, sand, cement, lime, anhydrite,aluminium slurry and water.

Hazard identificationWhen used correctly for their intended purpose, andprovided normal good standards of building practice arefollowed, no significant hazards exist.

First aid measuresThere are no specific requirements when using aeratedconcrete blocks other than the appropriate treatment ofminor injuries.

• Damage to skin – wash with soap and water and apply sterile dressing.

• Dust in mouth or eyes – irrigate liberally with water.

• Accidents where products strike or crush parts of the body should be referred to a suitably qualified medical practitioner. In all cases of doubt, or where symptoms persist, medical advice should be obtained.

Fire fighting measuresProducts will not support combustion.

Accidental release measuresNot applicable.

Handling and storageWhen blocks are banded or wrapped, care should betaken when releasing or removing this packaging asthere is possibility of loose blocks falling from the pack.Packs should not be lifted by the packaging alone, butby a suitable grab capable of carrying the weight of thepack, or by correctly positioned handling forks. Blockpacks should be stacked on dry, level ground no morethan 3 packs high, to reduce the risk of loose blocksfalling. Where blocks are handled manually, personalinjury due to strains or ruptures should be avoided if therequirements of The Manual Handling OperationsRegulations are implemented.

Exposure controls/personal protectionWhen cutting blocks with a saw, it is advisable to wear a dust mask to current H.S.E. or European approvedstandard to protect against the inhalation of dust, whichmay contain respirable crystalline silica. Protective

goggles, spectacles or face shields to BS EN 166 mustbe worn when cutting plastic bands under tension.

Suitable gloves should be worn to prevent skin abrasion,which could be caused by the rough edges of theblocks. Suitable head and foot protection should beworn where there exists the risk of products falling froma height.

Physical and chemical propertiesAerated concrete blocks are inert and solid whensupplied. The main constituents are pulverised fuel ash,which contains amorphous silica and various metaloxides, and cement, which is predominantly made up ofcalcium silicate and calcium aluminate.

Stability and reactivityNot applicable.

Toxicological informationNot applicable.

Ecological informationNot applicable.

Disposal considerationsRedundant plastic strapping and waste polythene canbe recycled where this facility exists, or disposed of by aregistered carrier at an approved landfill site. Wastepolythene can be incinerated under approved conditionsin compliance with the Environmental Protection Act.Advice on the preferred method should be obtainedfrom the local authority waste disposal officer.

Transport informationNo special precautions required.

Regulatory informationClassified as non-hazardous for conveyance and supply.

Other informationIn accordance with the Management of Health andSafety at Work Regulations, employers must carry out arisk assessment to ensure the health and safety of theiremployees and non-employees, who may be affected bytheir undertaking.


7575


76

Sitework

76

MortarThe composition of mortar is very often given insufficient consideration,and in many instances it is left to site operatives to decide on thespecification. Mortar forms an integral part of the wall, comprisingbetween 6 and 18% of the total wall volume when general purposemortar is being used, and approximately 2% when thin layer mortar isused. It is important therefore, that the appropriate specification isdetermined at the design stage.

Thermalite blocks can be laid in either general purposemortar or thin layer mortar. Mortars for use withThermalite should be as described in BS EN 998-2-Specifications for Mortar for Masonry.

General purpose mortarThe nominal thickness of general purpose mortar, inboth horizontal and vertical joints, is normally taken tobe 10mm, exclusive of any key in the jointing surface ofthe masonry units.

Specification of general purpose mortarWhen specifying general purpose mortar, the followingdetails of the project should be taken into account:

• the type of masonry unit to be used

• the structural requirements

• the degree of exposure of the site

• the level of workability required

• the location of the masonry, i.e. above or below, ground level

When selecting a suitable mortar specification, it isimportant to ensure that the composition is compatiblein strength with the blocks selected for the project.

Mortars are defined by designations (i) to (iv) inaccordance with Table 13 of BS 5628: Part 3. Basedon this table the following general use mortars arerecommended for use with Thermalite:

These mortar specifications are suitable for use with allproducts in the Thermalite range and may also be usedwith other types of masonry. They may be usedthroughout the United Kingdom for the construction ofinternal and external loadbearing and non-loadbearingwalls.

The use of mortar mixes other than those listed abovemay cause difficulties during construction and may leadto defects after completion.

Application notes for general purpose mortarCement-rich mortar specifications are non-resilient andsubject to high shrinkage. They are therefore, less ableto accommodate movement and may cause cracking incompleted walls.

It is important that the sand should be well graded andcomply with BS EN 13139, and that the water shouldcome from a clean supply.

Table 30 – Mortar designation (iii) for internal and external walls above d.p.c. (all proportions by volume)

1 : 1 : 6 cement : lime : sand

1 : 6 cement : sand with a plasticiser

1 : 5 masonry cement : sand

Table 31 – Mortar designation (ii) for use below d.p.c. (all proportions by volume)

1 : 4 cement : sand by volume

1 : 1/2 : 4 cement : lime : sand by volume


7777

The addition of either lime or an air-entrainingplasticiser to a lean mortar mix, will improve frostresistance and greatly improve workability, therebyincreasing productivity. Care should be taken to avoidmisuse of liquid plasticisers, as it is possible to producea workable mix with an unacceptably high sand : cement ratio. Masonry cements are less prone tomisuse than liquid plasticisers.

Cement : lime : sand mortars have better wet adhesionand early strength with both bricks and blocks, thanmixes incorporating plasticisers or masonry cement, andmay have superior bond characteristics. They also allowsmall amounts of movement without cracking.Additionally, lime tends eventually to seal hairline cracks.

Tests carried out on behalf of the Mortar ProducersAssociation have indicated that walls built with cement: lime : sand mortars have better resistance to driving rainthan those built without lime.

Reduced adhesion between the masonry units and themortar may be caused by inadequate cement content,excessive air content or the use of unspecifiedadmixtures. Satisfactory adhesion can only be achievedby correct mix design and careful raw material selection.

Pre-mixed and ready-to-use general purpose

mortarsThe use of these mortars can be a means of ensuringconsistent quality. Also, where large volumes of mortarare required, the storage of large quantities of raw

materials and their potential deterioration can beeliminated.

One tonne of mortar will be sufficient for approximately600 No or 60m2 of 440(l) x 100(w) x 215(h)mmblocks.

Thermalite Thin Layer MortarFor a description of properties and guidance in the useof Thermalite Thin Layer Mortar, please refer to Thinjoint masonry, pages 24-31.

Cold weather workingBS 5628: Part 3 states that masonry should not be builtwhen air temperature is at or below 3°C and falling, orunless it is at least 1°C and rising. Thin layer mortarshould be used in conditions above 5°C (see page 26),although it may be used at 3°C on a rising scale.Conditions should be regularly monitored and accountshould be taken of the wind chill factor and structuralstability of certain details. The use of covers will protectmaterials when not for immediate use. Frozen materialsmust not be used. It is essential to protect newly laidmasonry from incidental conditions and ensure that it isinsulated from frost.


78

Sitework

78

WorkabilityThermalite blocks are not only easy to handle, they are extremelyworkable and can be easily cut, sawn and chased accurately with ordinaryhand tools.

Chasing limitationIn accordance with the Building Regulations, verticalchases in walls should be not deeper than one third ofthe thickness of the wall, and horizontal chases notdeeper than one sixth of the thickness of the wall.


7979

FixingsMost traditional fixing methods are suitable for use with all types ofThermalite blocks, but the properties of the material also enable a numberof special fixing methods to be used.

LoadingThe load which can be supported by a fixing dependsupon the following factors:

a) strength of background material.

b) positioning of fixings.

c) strength of bond between fixing device and background material.

d) size of fixing.

When fixings are subjected to pull-out tests, failurenormally occurs as a result of bond failure between thefixing device and the background material. The strengthof this bond can be optimised by careful installation.

Fixing typesThe majority of general purpose fixings give excellent performance in Thermalite. Examples of such fixings, together with recommendations on how and where theyshould be used, are as follows:

Cut nails

Cut nails of tapered aluminium or mild steel, with a rectangular cross section, form an excellent bond whendriven into all types of Thermalite. They arerecommended for fixing skirting boards, timber battensfor cladding and tiling, and lightweight door linings.Where there is a risk of timber splitting, pre-drilling ofthe timber or the use of longer 'slimline' cut nails isrecommended.

Cut nails should be driven in askew at approximately 450mm centres. Recommended penetrations are 75mm into Turbo and 50mm into other Thermaliteproducts.

Direct screwing

It is possible to screw No. 12 or No. 14 wood screwsdirectly into Thermalite Shield blocks. A few taps with ahammer will create a pilot hole for the screw, which canthen be tightened with a screwdriver. This provides asuitable method for fixing medium-weight door linings,where the screws should be at approximately 450mmcentres, and should penetrate at least 50mm into theblockwork. Overtightening should be avoided.

Screws with plugsThe most common method of fixing into masonry, i.e. wood screws with plugs, is eminently suitable for usewith Thermalite blocks. Both fibre Rawlplugs and plasticplugs, with either toothed or smooth sides, can be usedsuccessfully with Thermalite.

The strength of the bond between the fixing and theThermalite block also depends critically on the size ofhole used. The size of a drilled hole will depend upon anumber of factors:

a) type of Thermalite block.

b) size and type of drill bit (use a steel, not a masonry bit).

c) speed of drill (use as slow a speed as possible).

d) type of drill (do not use hammer action).

Correct use and suitable choice of drill size (0.5mmsmaller than the diameter of the plug being installed)will produce a parallel-sided hole, into which the fixinghas to be tapped home with a hammer.

Frame fixings

Frame fixings are 'through' fixings, which consist of extended plastic plugs that pass through the frame andinto the blockwork. They are usually supplied completewith a complementary sized screw and have theadvantage of accurate hole alignment and depth. The presence of the plastic sleeve in the door framealso acts as a shock absorber.


80

Sitework

80

Fixings

Special aircrete fixingsSpiral plug

The most common type of fixing specifically designedfor aircrete consists of a plastic plug which, when drivenor screwed into a pre-drilled hole, cuts a thread in thematerial. A wood screw can then be driven into thehollow centre of the fixing.

Grouted fixing

Other special fixings use an 'under-cut' hole in theblockwork requiring a special cutter. The fixing is thenexpanded or grouted into the hole, the grout beinginjected through the hollow centre of the fixing.

These fixings are very strong and suitable forparticularly heavy duty tasks such as fixing boilers andradiators.

Spiral nails

Spiral (or helical) nails, manufactured from stainlesssteel, provide an excellent hammered-in fixing forsecuring timber to Thermalite. The small, uniform cross-sectional area eliminates the risk of damage to timberand block.

'Sleeved' nails

These knock-in 'through' fixings expand into theblockwork after they have been driven to a certaindepth. They provide an excellent fixing, even if they havebeen loosened, because the pull-out load is sustained.

Square anchors

These are reinforced glass-filled nylon, hammer-infixings that require no pre-drilling and provide a secureanchor for size 6-10 gauge screws in Thermalite Turbo,Shield and Party Wall blockwork.


8181

Table 32 – Shield (failing load values)

Plug diameter (mm)Nylon/plastic plugs 8 8 10 10 12

Screw size No.10 No.12 No.10 No.12 No.12

Penetration (mm) 40 40 50 50 50

Hole diameter (mm) 7 7 9 9 11

Failing load (kg) 91 106 141 132 116

Cut nails

Penetration (mm) 50 75 100

Failing load (kg) 42 74 157

No 12 wood screws 12 12

Penetration (mm) 50 63

Failing load (kg) 142 142

Table 33 – Paint Grade Smooth / Party Wall (failing load values)

Plug diameter (mm)Nylon/plastic plugs 8* 8* 10 10 12 12

Screw size No.8 No.12 No.8 No.14 8mm 10mm

Penetration (mm) 40 40 50 50 60 60

Hole diameter (mm) 7 7 9 9 11 11

Failing load (kg) 157 158 133 134 162 161

Cut nails



No 12 wood screws 12 12

Penetration (mm) 50 63

Failing load (kg) 150 186

Rawlnut type No: 3240 5250 5380 6250 8509

Hole diameter (mm) 7 10 10 13 18

Length (mm) 23 26 39 36 50

Spacer length (mm) 25 32 38 32 38


Failing load (kg) 100 163 209 308 469

* 4-way expansion plug

Table 34 – Turbo (failing load values)

Plug diameter (mm)Nylon/plastic plugs 8* 8* 8 8* 10 10 12

Screw size No.10 No.12 No.14 No.14 8mm 8mm 10mm

Penetration (mm) 40 40 40 50 50 60 60

Hole diameter (mm) 7 7 7 9 9 10 10

Failing load (kg) 89 89 75 112 89 83 89

Cut nails



Plug diameter (mm)Fibre plugs 8 10 12 14 16 18 20

Screw size No.8 No.10 No.12 No.14 8mm 8mm 10mm

Penetration (mm) 40 40 50 50 50 50 50

Hole diameter (mm) 7 9 11 13 15 17 19

Failing load (kg) 93 100 140 174 184 194 204

* 4-way expansion plug

Table 35 – Hi-Strength 7 (failing load values)


Screw size 6 6 8 8 10


Hole diameter (mm) 7 7.5 9 9 9

Failing load (kg) 117 164 271 188 221

Table 36 – Hi-Strength 10 (failing load values)


Screw size 6 6 7 7 14


Hole diameter (mm) 7.5 8 9 9.5 10

Failing load (kg) 116 121 202 357 377

Failing load valuesThe following tables provide indicative pull-outperformance of common fixings into Thermalite. More detailed information should be obtained from themanufacturers.

Below are the average results of 12 tests carried out todetermine the force required to withdraw 75mm and100mm cut nails and various size screws, fixed in fibreand nylon/plastic plugs, from Thermalite Turbo. All cut nails and screws were driven in to leaveapproximately 13mm protruding.


82

Sitework

82

Internal finishes

IntroductionThe building should be allowed to dry out for areasonable period after roofing before any internalfinishings are applied to the walls.

Plaster undercoatsThe following mixes are recommended for floating coats:

a) 1 : 1 : 6 cement: lime: sand by volume(a 1 : 2 : 9 cement: lime: sand mix may be used, except under cold winter conditions).

b) 1 : 6 cement: sand by volume, with the addition of an approved plasticiser used in accordance with the manufacturer’s instructions.

c) Pre-mixed gypsum bound lightweight aggregate undercoat plaster.

d) Pre-mixed cement-lime bound lightweight aggregate undercoat plaster.

Note: The sand used in both external and internal render finishes should comply

with BS EN 13139.

Plaster finishesUndercoats a) and b) may be finished with a neatgypsum Class B finish coat. Undercoats c) and d) maybe finished with a lightweight pre-mixed gypsum, orgypsum lime bound finish coat, respectively. Machine-projected plasters may be suitable for use on Thermalitewalls.

Dry liningsThe following systems are suitable for use on Thermalite walls:

a) Plaster dab method

Bonding compound dabs should be used to fix theboards to the wall. The dabs are applied to the wall andshould be the length of the plasterer's trowel and 50mmto 70mm in width. Dabs should be 50mm to 70mm apartvertically and approximately 300mm apart horizontally.The boards are then pressed tightly into position and theface plumbed and lined. They should be wedged inposition until the plaster dabs have set. Dabs should onlybe applied for one board at a time.

It may be advantageous to apply a bonding agent to thewalls prior to the dry lining operations. Multi-purposeplaster should be used to fix insulating plasterboardlinings.

For sound insulation purposes, it is recommended that acontinuous horizontal ribbon of adhesive is applied atfloor and ceiling levels.

b) Timber batten method

Timber battens 50mm wide x 20mm thick should befixed at centres in accordance with the lining boardmanufacturer's recommendations. The battens shouldbe correctly aligned and fixed with cut nails of sufficientlength to penetrate the Thermalite by at least 50mm (itmay be necessary to increase the depth of penetrationinto Turbo). The board should then be fixed to thebattens using flat-headed galvanised nails.

c) Metal framing systems

British Gypsum Limited manufacture a metal framingsystem that may be fixed to Thermalite walls and willprovide a satisfactory internal finish. The applicationshould be carried out in accordance with themanufacturer's instructions.

Taper edge boards should be jointed with a proprietaryjoint filler, taped and finished.

Sealing edgesIt is a requirement of the Building Regulations that gapsbe sealed between dry lining and masonry walls at theedges of openings, such as windows and doors, and atthe junctions of walls, floors and ceilings. One method isto seal with continuous bands of fixing plaster.

Painting directPaint Grade Smooth blocks built fair-faced can bepainted internally with any alkali-resistant paint, plasticemulsion paint being particularly suitable. Any smallholes that occur on the faces of the blocks should befilled before painting.

StorageAs with all concrete products, it is desirable thatThermalite blocks be kept dry by stacking them closetogether, with blocks laid flat on top of the stack.Blockwork should be allowed to dry out thoroughlybefore commencement of rendering or plastering (BS 5628: Part 3 and BRE Digest 342).

Ceramic wall tilingIn the United Kingdom, as in many other Europeancountries, tiles are now used extensively, not just inkitchens and bathrooms, but also in other spaces suchas entrance halls and communal areas.

Tiles may be glazed, unglazed or partly glazed. Therange of sizes, thicknesses and accessories available isnow extensive, although the vast majority of tiles aresquare or rectangular.


8383

Tiling specification

The specification of internal wall tiling should be in accordance with BS EN 14411.

At present there is no British Standard by which todefine tiles suitable for use in external situations.Therefore, please refer to the ISO 10545 series ofstandards and consult individual tile manufacturers forfurther advice on the choice of tile necessary towithstand the conditions to which they may be exposed.

Rendering for tiling

A sand/cement render provides a suitable intermediate substrate onto which tiles can be securely fixed. (See also External Finishes on page 84.)

Pre-treatment is seldom necessary as Thermalite isclassed as a 'medium suction background'. However, thismay vary under differing climatic conditions.

Although the scratch finish, which is an identification characteristic of Thermalite blocks, provides a key, rendercan also be applied to Thermalite Paint Grade Smoothblocks. The key can be improved by recessing the mortarjoints. For tiling purposes, rendering to blocks with adensity of less than 625kg/m3 (i.e. Turbo and Shield)should be reinforced with welded wire mesh secured tothe blockwork in accordance with BS 5385: Part 1.

It is normal practice to apply render in two coats, whichshould not have a combined thickness greater than 13mm. It is normal for the first coat to be thicker thanthe second.

The first coat should be finished with a comb andallowed to harden and dry out before applying thesecond coat. Again, this should be lightly combed toreceive the subsequent adhesive.

In accordance with BS 5385: Part 1, the recommended render mix for tiling purposes on Thermalite walls is:

1 : 4 Portland cement: sand by volume.

The sand should comply with BS EN 13139.

Plastering for tiling

It should be noted that a cement/sand render provides amuch stronger background for tiling than plasterworkand wherever possible, for example in new installations,cement/sand render should be specified. Nevertheless,tiles can be fixed satisfactorily onto plastered Thermalitewalls, provided a suitable adhesive is used and thecorrect procedures are followed.

BRE Defect Action Sheet No 137 advises that the useof gypsum plasters should be avoided where repeatedor persistent wetting of the wall may occur.

Unrendered Thermalite wallsTiles may be bedded directly onto blockwork walls using proprietary adhesives. It is important to leave the wall to dry out for as long as possible before commencingtiling. The tiles should be fixed onto a clean, dust-freeand true Thermalite surface.

AdhesivesThere are two basic types of adhesive:

a) Organic-base

b) Cement-base

Adhesives are being continually developed and Table 3in BS 5385: Part 1 gives guidance on the choice ofadhesives now available.

Fixing and bedding procedures vary; it is thereforeimportant to follow particular adhesive manufacturer'sinstructions concerning, for example, mixing procedure,type of trowel to be used and working time.

Accommodation of movementAs with most building materials, careful considerationneeds to be given to movement in the tiling and thebackground caused by factors such as temperature andmoisture changes.

BS 5385: Part 1 recommends that this movement be controlled by the inclusion of simple movement joints, and that the following movement joint locations shouldbe carefully considered at the design stage:

a) Structural movement joints.

b) Junctions with different finishes.

c) Changes in background material.

d) At openings, or where changes of alignment occurand stresses are likely to be concentrated.

Large tiled areas should be divided into panels with movement joints at 3 to 4.5m centres, both horizontallyand vertically. Movement joints in a blockwork wallshould extend completely through the tiling, adhesiveand rendering.

For further information, please refer to MovementControl on page 65 in the Design Detailing section.


84

Sitework

84

External finishes

IntroductionRender specification is determined not only by thenature of the substrate, but also by the location of thebuilding. General purpose sand/cement renders aredefined by mix types (i) to (iv) in accordance with Table1 in BS 5262*. Table 2 in BS 5262* confirms that mixtype (iii) (1 : 1 : 6) is suitable for application to aeratedconcrete blockwork in areas of sheltered, moderate andsevere exposure conditions.

If a cement-rich mix is used for rendering Thermalite,the amount of water necessary to hydrate the cementgives rise to a higher rate of drying shrinkage in therender than in the blockwork. This differential shrinkagecan lead to a shearing action building up between thetwo materials, resulting in failure. However, this issuecan easily be avoided by adopting a compatible renderspecification.

GeneralBS 8104 describes a method of establishing the localspell index for walls subject to wind-driven rain. Thistakes account of meteorological data and expresses theworst expected conditions prevailing in a spell of badweather during any three year period.

Since such data is variable, the definitions of theexposure categories overlap and a range of indices isrecommended for each category. Although the severeand very severe categories apply to much of the West ofScotland and Wales, for example, the exposure ratingalso takes account of local features which affordprotection to a building. It is therefore possible for a'severe' site to exist within an area deemed to be in the'very severe' category.

On request, the Technical Advisory Service will assessany building to determine the suitability of blockthickness and external finish, with reference to exposurecategories.

See also information relating to ‘Moisture Penetration’,page 50-51.

SpecificationIt is normal practice to apply render in two coats. The first coat (undercoat) should be trowelled on to athickness of 10mm to 16mm and scratched. Anadequate period of time should elapse between theapplication of coats in order to allow the undercoat todry out thoroughly, but not too quickly, before the nextcoat is applied.

The thickness of the final coat will be governed to someextent by the texture required, but will normally be 6mmto 10mm, as finished. The final coat should be thinnerand no stronger than the undercoat and this, in turn, nostronger than the substrate. The finishes suitable forexternal renderings onto Thermalite blocks are classifiedby BS 5262* as follows:

a) Float finish.b) Scraped or textured, hand-applied.c) Dry-dash, dry-thrown by hand.d) Machine-applied, Tyrolean or power spray.

MixesWhen selecting a suitable render specification it isimportant to ensure that the composition is compatibleand not too strong (or weak) in relation to the strengthof the substrate. The following recommendations - mixtype (iii) - take this into account and are based on therequirements of BS 5262* and BS EN 13914-1.

To gain benefit in both accommodation of movementand resistance to rain penetration, the preferred rendermix is:

a) 1 : 1 : 6 cement : lime : sand by volume.

The addition of lime improves workability andcohesiveness. It improves the render's ability toaccommodate movement, thereby reducing thetendency to crack. The lime should be hydrated andcomply with the requirements of BS EN 459-1:2001.

b) 1 : 6 cement : sand by volume, with the addition ofan approved plasticiser used in accordance with themanufacturer’s instructions.

c) 1 : 5 masonry cement : sand by volume.

The sand in all coats should be sharp, clean and complywith the requirements of BS EN 13139. The grading ofthe sand is extremely important as it will affect thequality and performance of the finished render. Sandswith excessive proportions of very fine material shouldbe avoided as the finer the sand the greater therender's capacity to hold water.

In addition to inhibiting adhesion, excessive moisture retention will lead to high drying shrinkage, withconsequent cracking and spalling. Conversely, a coarsesand retains insufficient moisture within the render,resulting in inadequate hydration and adhesion.

*No longer current, but still cited in Building Regulations. Use in conjunctionwith BS EN 13914-1.


8585

The use of ready-mixed renders to help avoidinconsistency in site batching is highly recommended.Traditional sand/cement render should not be applied toan external leaf of Turbo material less than 215mmthick. This is to minimise the risk of failure caused bythe differences in tensile strength between the finishand background material. If a ‘technical’ render systemsolution is proposed, the advice of the render systemmanufacturer must be sought.

Modern render systemsA wide range of cement-free and modified cementrenders, some reinforced by fibre or mesh to resistthermal movement of the backing masonry, are readilyavailable for application to Thermalite. These are oftenreferred to as ‘technical renders’. As these technicallysophisticated products often require the services of anapproved applicator, advice should be sought from themanufacturer prior to specification.

Preparation of backgroundAlthough the scratch finish, which is primarily anidentification characteristic for Thermalite blocks, helpsprovide a key, it is also possible to apply render toThermalite Paint Grade Smooth blocks. The scratch keyshould be augmented by recessing the mortar jointsduring construction.

The blockwork should be clean and free from dust,loose particles and any contamination which may haveoccurred during construction.

Thermalite normally provides a 'medium suctionbackground'. Given certain ambient conditions, or wherethe blockwork has been allowed to dry out, high rates ofinitial suction may be experienced. This condition canhave an adverse effect on hydration and adhesion andmeasures should be taken to reduce the suction. Thiscan be done by applying water using a stock brush or afine spray immediately prior to rendering, taking care toavoid saturation of the surface.

Alternatively, should high rates of suction persist, then aspatterdash treatment or the application of an approvedbonding agent may be considered. Further informationmay be obtained from Hanson’s Product ServicesDepartment.

Accommodation of movementIn accordance with the recommendations of BS 5628:Part 3 and BRE Digest 342, construction joints should be provided at maximum 6 metre centres, in order tominimise the effects of movement. See also MovementControl on page 65 in Design Detailing section.

External wall insulation systemsThere are many external wall insulation systemsavailable that are widely used to improve the thermalinsulation performance of external walls of existingbuildings. However, these systems can also be used onexternal walls of new build projects.

The systems vary depending on the particularmanufacturer, but generally consist of a thermalinsulation such as EPS insulation board or rigid fibreboard, secured to the external wall with fixings directinto the wall. A base render coat is then applied to theinsulation into which a fibre or metal reinforcing mesh isplaced. The reinforcing mesh is also usually fixed directinto the external wall. The system is then completedwith the application of a proprietary render.

It is advisable to ensure that the system to be used issupported by independent certification and full technicalinformation is obtained from the manufacturer.

External tilingExternal tiling should only be fixed to render finishes which have been applied over anchored re-enforcingmesh. It is also important to follow the guidancecontained in BS 5385 : Part 3, in particular Table 3 ofthe standard, where information relevant to externaltiling is contained.


86

Sitework

86

External finishes

CladdingThe two most commonly used external cladding systemsare weather boarding and tile hanging. In both cases, itis advisable to include a suitable vapour permeablemembrane between the cladding and the blockwork.

Weather boarding

Whilst weather boarding can be fixed directly to theThermalite surface, it is more commonly fixed to verticalbattens securely fixed to the Thermalite blockwork.

Tile hanging

Clay or concrete tiles or slates can be used to create an attractive external façade and are normally nailed tohorizontal timber battens which, in turn, are securelyfixed to the Thermalite blockwork.

WonderwallHanson's Wonderwall cladding system provides adurable, decorative and thermal insulating finish forexternal walls. The system comprises an insulated panel,prebonded to a vacuum-formed brickwork coordinatingcarrier sheet. This composite panel can be fixed directlyto Thermalite using proprietary fixings. Brick slips arethen fixed to the carrier sheet using a purpose madeadhesive, and finished off with a specialist pointingmortar.


87

6 Other informationSales and Technical Advice 88

Quality 90


88

Sales and Technical Advice

Sub head

88

Other information

Customer servicesHanson has a reputation for providing first classcustomer care and this is supported by the operation of a dedicated Customer Contact Centre.

As a result of continuous investment we are able toensure that a team of customer service staff are able tooffer a fast response time to enquiries.

Wherever you are, the Thermalite Contact Centre canbe reached by simply dialling the numbers shown below.Your call will be answered by one of our specialist teamwho are able to offer a range of services:

• Product information• Quotations• Orders• Distribution facilities• Stockist information

If the enquiry is of a more technical nature, Hanson’sProduct Services department is on hand to offer moreexpert advice. Alternatively, you can arrange to see oneour Area Sales Managers who will be pleased to meetyou at your office or on site.

LogisticsDeliveries

Thermalite orders can be placed with leading Builders’Merchants throughout the United Kingdom for delivery direct to site by our team of dedicated professionaldrivers.

PackagingVoid packs

Void packaging has been developed in response to ourcustomers' demands for packs that eliminate the needfor a pallet and can be easily moved around the yard oron site. For further information, please contact CustomerServices.

Grab packs

Grab packs are shrink-wrapped with strong plastic film,which provides protection for the blocks and stability tothe packs. Grab packs can be easily unloaded andmoved using normal brick grabs, thereby saving onpallet costs. Pallets can be supplied on request.

In addition to ensuring that the product is kept in goodcondition, the Thermalite packaging is clearly markedwith the product description, leading to improvedsecurity and management of materials.

Please contact Customer Services on:

Tel: 08705 626500Fax: 08705 626550email: [email protected]

Hanson’s website allows you to access information on

products, applications and performance quickly and easily.

This includes the latest on Building Regulations and

relevant technical advice.

www.hanson.biz/uk


8989

Site storageHanson recommends that Thermalite products bestacked not more than three packs high on firm, levelground.

Product servicesHanson provides a free technical advisory service(08705 626500), staffed by a qualified team withspecialist knowledge of all products and theirapplication. Advice is offered on interpreting theBuilding Regulations and methods of compliance usingspecially developed software programs. These areupdated when necessary, to keep abreast of changes toBritish and European Standards, Codes of Practice andBuilding Regulations.

This service should not be regarded as a substitute forthe role carried out by the architect or structuralengineer.

Members of our technical team are able to providepresentations, with CPD approval, on the use ofproducts and regulatory compliance.

Thermal calculations

As a result of the continual drive to conserve fuel andpower, the service will provide cost-effective solutions toenable compliance with the requirements.

Energy ratings

Specialist advice can be given on the StandardAssessment Procedure (SAP) only when Thermaliteblocks are used to comply with the BuildingRegulations.

Sound insulation assessments

The provision of recommendations on sound insulationfor all buildings when Thermalite blocks are used tocomply with the Building Regulations.

Accommodation of movement in masonry

A service to detail the type and location of movementjoints and/or bed joint reinforcement in concrete blockmasonry walls to comply with the Building Regulations.


90

Other information

90

QualityHanson manufactures its Thermalite product to a quality assured system inaccordance with EN ISO 9001 and BS EN 771-4. Hanson also has a UKASaccredited laboratory for testing masonry units to the applicable productstandard, with tests including compressive strength, transverse strength,moisture movement and dimensional accuracy.

The laboratory is also accredited for testing thermal conductivity of masonry and insulation materials to BS EN 12664, BS EN 12667 and ISO 8302. The laboratory continues to work closely with authorisedapproving bodies when conducting field soundtransmission tests to BS EN ISO 140-4 and is UKASaccredited for this test method including impact testingof floors to BS EN 140-7.

To assist in the development of thin joint masonry, theThermalite Laboratory holds UKAS accreditation for thetesting of mortars.

Joint work has been conducted with such bodies as theBBA, BSI, BRE and individual universities.

Other non-accredited tests carried out at the laboratoryinclude fixing/pull-out strengths, mortar/plaster bondstrength, equilibrium moisture content, freeze/thawresistance and water absorption.

As part of the company’s BS EN ISO 9001 systemeach Thermalite manufacturing site has a dedicatedlaboratory where testing is routinely conducted.

00/372091/2723ENP168

0640

All manufacturing locations hold a Kitemark license.Additionally, Thermalite products have the independentaccreditation of the British Board of Agrément.

Registered Trade MarksThermalite® is a registered Trade Mark. In addition, the following range of Trade Marks are registered:

Thermalite Floorblock®

Thermalite Shield®

Thermalite Trenchblock®

Turbo Block®


91


92

Other information

Other Hanson products

Aggregate BlocksHanson is a market leader in the manufacture and supply of aggregate concrete blocks, annually producing over 7.5million m2. Aggregate blocks are a robust and economic product, featuring high compressive strength and excellentsound insulation to help meet the requirements of Building Regulations.

Floors and PrecastWith an extended product range, expanded manufacturing facilities and increased design capabilities, Hansonprovides comprehensive engineered solutions for pre-cast concrete flooring at every level in both domestic housingand commercial premises.

AggregatesHanson Aggregates has more than 400 operations from Falmouth to Shetland. Core products include crushed rock,construction sand and gravel, asphalt and Premix concrete and mortar. Special products include rail ballast,agricultural and burnt lime, graded sands for play pits, golf bunkers and horticulture, industrial sands for glassmaking, Redgras sports surfacing, armour stone, granite paving, natural stone from Bath and the Cotswolds andrecycled aggregates. Complemented by an existing ready-to-use wet product, Hanson dry silo mortar (DSM) offerscomplete mortar solutions to meet individual customer requirements.

Packed products and landscapingThe Packed Products and Landscaping collection consists of decorative garden products, packed dry mixconcretes and mortars, bagged sands and gravels and block paving.

Chimneys, flues, ridge tiles and fittingsHanson Red Bank produces one of the UK’s most comprehensive range of chimney components including fire-backs, clay and concrete flue liners as well as the largest range of chimney pots and terminals. In addition, theCompany produces a wide range of clay and concrete ridge tiles and fittings. These not only include standard plainand capped angle ridges but a vast array of decorative ridge tiles and finials as well as the ability to offer a bespoke service if required.

Modern Methods of ConstructionWith its market-leading position, Hanson has developed a range of prefabricated building products that enablehousebuilders and developers to gain all the advantages of quicker build times and quality of workmanship. By usingtraditional building materials, the Hanson product range satisfies the requirements of end users who consistentlyfavour traditionally built homes.

BricksAn extensive range of facing bricks in over 300 different colours and textures. Within this diverse rangethere’s something to suit every building project, from the most innovative architectural concept, to anindividual self-build scheme.


Hanson can now provide a single source solutionfor many products across a wide variety ofbuilding projects, all backed by the sales supportand technical service that is the strength of thisdivision.

For further information on any of the otherproducts within Hanson’s range

please contact:

Hanson Building ProductsHead Office Stewartby Bedford MK43 9LZ

Tel: 08705 258258Fax: 01234 762040

Email: [email protected]: www.hanson.biz/uk

93

DisclaimerAll product and technical information contained in thisbrochure is considered correct at the time of publication.

This brochure is printed on paper containing 75%recycled waste and 25% virgin fibres from asustainable timber source.


aircrete blockstechnical manual

aircre

teblo

cks

technicalmanual

Customer Services:

T 08705 626500 F 08705 626550E [email protected] www.hanson.biz/uk

Hanson Building ProductsHead OfficeStewartbyBedfordMK43 9LZ

Aircrete Blocks CI/SfB

February 2007Ff4

Uniclass L3221: P2

464.5 Thermalite binder_2:464.5 Thermalite binder_2 7/3/07 13:23 Page 1

Aircrete Blocks Technical Manual

Documents

Transcript of Aircrete Blocks Technical Manual