Construction Practice 1 for Technician

8/8/2019 Construction Practice 1 for Technician

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Construction Practice for Technician & Diploma Students -Volume One

ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 1PRELIMINARY SITE WORKS

These are the initial operations carried out on the site before the commencement of theactual structure. They include:

1. Access to the site2. Clearing the site3. Access on the site

4. Fencing and hoarding5. Datum establishment6. Provision of hutments7. Provision of services

8. Soil investigationAccess to the site

Usually, roads are integral part of the contract especially if it is a housing estate or a

factory. This means no special requirements will be necessary for the provision of accessto the site. Otherwise if no permanent roads are required it is important to constructtemporary roads.Factors to consider when constructing access to the site:

1. Distance to site location2. Correct lay out of hutments3. Area size of the site4. Sign post erectionSite clearance

This involves demolition existing structures (if any), grubbing out of roots, bushes, stumps

etc. and topsoil removal. The depth of the vegetable topsoil may vary according to thegeographical strata and information. The site may cleared using two one of two methods orboth. This may be either mechanical or manual. The skimmer and grader are popularly usedfor this purpose. On small sites hand tools such as shovels, pick axes, cutlasses etc. areused for this purpose. The topsoil must not be used for any hardcore filling but for onlyagricultural purposes.Construction Practice for Technician & Diploma Students -Volume One

ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 2Reasons for the removal of vegetable top soil

1. To provide a hard level surface for the commencement of the building

2. Vegetable soil contains the organisms and chemicals necessary for the growth ofplants3. It has unreliable bearing capacity

4. Vegetable top soil is also removed to prevent plants from growing underneath theground floor and encourage dry rot5. It is unstable and cannot be compacted into a solid natural foundationTemporary roads

A hard dry surface must be provided to enable vehicles to be driven to the site. The


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materials for the road surfaces to be provided may include:i. Ballast, hogging or hardcoreii. Patent fabric of welded steel

iii. Timber sleepersBallast, hogging or hardcore

This can be laid and rolled into a hard surface if good drainage is provided, this road canbe most efficient and economical, provided it is laid on a hard dry surfaces.Patent fabric

This gives an excellent riding surface and can be laid on a ground which is a little bit soft.The material also allows heavy vehicles to move safely on slightly soft ground. The groundis shaped and cambered to shed water. The edges of the fabric must be pinned down toprevent the edges from curling up, which could cause damage to lorry tires personneltripping off.drainage trench

50mm hogging or75mm hardcore

4mroad surfaced with hogging or hardcoreCamberConstruction Practice for Technician & Diploma Students -Volume One

ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 3Timber sleepers

Timber is expensive but can be used to an advantage. The ground is prepared and twochannels cut, one on each side. The sleepers are then laid and nailed to the lower membersto prevent dislodging.Methods of Enclosing The Site & Their Protection

There are two methods of site enclosure:a. Fencingb. HoardingThe type of protection and enclosure chosen will depend on the1. Degree of security required2. Cost implications3. Type of neighbourhood

drainage trench

patent fabric4m

road surfaced with patent fabricfabric pegged down at dgesCamberConstruction Practice for Technician & Diploma Students -Volume One

ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 44. Duration of contractThe hoarding is erected when the work has started on the site for the following reasons:


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1. To prevent the public from having free access2. To safeguard the structure3. To safeguard the building materials

4. To prevent the public from dust and noise associated with construction activitiesThe fence is used for the following purposes:

1. Defines boundary2. Limits the site3. Serves as a barrier for protection4. Restricts movement5. Limits or stops view6. Forms visual link/feature between unit blocks.Example of Fences

1. Chain link2. Woven wire3. Strained wire

4. Cleft chestnut pale5. Close boarded.6. Wooden palisades7. Metal continuous bar8. Woven wood wattle panel9. Concrete panelConstruction Practice for Technician & Diploma Students -Volume One

ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 5The fan hoarding

The fan hoarding fulfils the function of directing falling debris back towards the building

or scaffold. It is placed at a level above the normal traffic height. If hoarding is abovepublic footpath it should be lined with polythene or similar sheeting.Construction Practice for Technician & Diploma Students -Volume One

ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 6hole through existingwall for supportsupports @ 600 c/csheeted deckstruts @ 600c/cfan hoarding details

Construction Practice for Technician & Diploma Students -Volume OneANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 7Construction Practice for Technician & Diploma Students -Volume One

ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 8Demolition

This is the complete destruction of the structure. It is the reverse order of construction.The method of demolition a particular structure would be determined by


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1. The size of the building2. Its type and method of construction3. Its location within the site boundary

4. The distance away from surrounding buildings5. He amount of recoverable or salvageable materials

6. The expertise of a particular contractorReasons for demolition

1. Structural failure - that is the structure is unsafe because of degeneration

2. Progress of society no longer required due to changes in demand3. Economic use of landConstruction Practice for Technician & Diploma Students -Volume One

ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 94. Economic consideration (the structure will cause too much to be repaired)This is a specialist operation and must be done by a specialist contractor. By employingan expert numerous advantages would be achieved, thus

1. He can salvage some of the materials2. He can appreciate the factor affecting safety3. He will also have adequate insurance cover in the event of any mishapThere are two types of demolition1. Total demolition2. Partial demolitionTotal demolition

This is where the whole structure is demolished.Partial demolition

This is where only part of the structure is removed.

Demolition techniques1. Hand demolition2. FragmentationHand demolition

This involves progressive dismantling of the building in the reverse order to its

construction. This may be used where there are severe site restrictions and/or partialdemolition is required. This is employed where salvageable materials are valuable. Thework is done with hand held tools plus lifting appliances to support main members as theyare released and to lower them to the ground when freed. No debris should be allowed tofall free unless the point of fall is at least 6.0m or half the height from which it is

dropped away from a public highway or adjoining property.Fragmentation

This is the process of reducing a building to a heap of rubble by the cheapest methodsavailable. The methods available are1. Pusher armConstruction Practice for Technician & Diploma Students -Volume One

ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 102. Deliberate collapse


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3. Rope pulling4. Explosives5. Demolition ball

6. Bursting7. Thermal methods

Pusher armThis is done using a steel or timber beam attached to a mechanical excavator and pushesover sections of the structure rather than dismantling it. The machine should be operated

from outside the building so that the debris falls inwards. This method is suitable forrelatively low structures within the reach of the pusher arm.Deliberate collapseThis technique reduces the building to a heap of rubble by the removal of a number of key

structural members. It is quick and reasonably safe in expert hands but produces a lot ofnoise, vibration and dust. The removal of the key members may be effected by pullingthem out by wire rope or blowing them out with explosives.

Rope pullingThis uses a wire rope which is well anchored winched or tracked or heavy vehicle pulling topull over successive portions. It is suitable for masonry buildings over 21m. The pullingrope should always be of length such that the horizontal distance from the winch to thebuilding is twice the height of the building being demolished.ExplosivesThis is the most dramatic method. Charges of explosives are placed at the base of thestructure and detonated to cause partial or complete collapse. For a larger structurethere may be controlled succession of blasts which brings it down in stages.

Demolition ball

This method employs a weight, suspended from a crane and swung against or dropped ontothe structural members. It is highly skilled operation and should only be carried out withinclearly defined limits to avoid overloading or overstressing the crane. Usually the roof is

removed, 50 to 75 percent of floors removed by hand before balling work starts.Construction Practice for Technician & Diploma Students -Volume One

ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 11Bursting

A cavity is formed in critical members of the building and are forced to enlarge . causingthe members t fracture, leading to a controlled collapse. The force is applied by either agas-expansion or hydraulic burster. The gas-expansion burster is made up of a cylinder

filled with gas which, when ignited by electrical charge expands rapidly into the cavity.Thermal methodsThis method combines thermal reaction on structural steel members in conjunction withwire rope pulling. The beam or stanchion to be severed has a mixture of metal oxide and areducing agent applied around critical point. When the mixture is ignited it liberates

enough heat to soften the metal sufficiently to allow the member to be pulled down.Provision of Hutments


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These are usually wooden structures erected on site to provide for a simple temporaryaccommodation or for leisure activities and offices etc.Classification of hutments

1. Mobile2. Semi-mobile

3. FramedA CRANE & A DEMOLITION BALLConstruction Practice for Technician & Diploma Students -Volume One

ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 124. Sectional5. Portable framed6. Air houseFactors to consider when erecting hutments:

1. Duration of contract2. Availability of space

3. Location of site4. No of employees

5. Size of contractThese hutments may also be used for storing the materials on site.Provision of servicesThe services which may encountered on or around a site are1. Water2. Gas3. Electricity

4. Telephone

5. Sewerage6. Oil7. TelevisionAll the services listed are classified into three areas:1. National2. Regional3. LocalThe appropriate board must be notified before any connection can be made. The following

information must be communicated to the local authority and permission granted beforework commences.

1. Name and address of the developer2. Location of the land to be developed3. Description of the proposed development4. Previous use of land5. Whether a new access would be required from the highwayConstruction Practice for Technician & Diploma Students -Volume One

ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 13


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6. Plan to which the permission refers7. 1:100 or 1:200 drawing to give a clear picture of the new building or alterationStorage and protection of materials

The type of storage facilities required of any material depends on the following factors:1. Durability whether it needs protection from the elements

2. Vulnerability to damage3. Vulnerability to theftCement

Cement is supplied in bulk, bags or in drums. Bulk cement is delivered to site by tankersand blown into storage silos by compressed air.Bagged cement, delivered on a wagon having a tarpaulin cover, should be stored in a closecabin, the floor of which is at least 150mmabove the ground. The bags should be storedclosely together to prevent the circulation of air.Aggregates

Aggregate should be stored on a hard, clean free draining surface. They may be stored in

bins or hoppers so that the stockpiles do not mix thus ensuring that different aggregates,types and sizes are kept separately.Bricks and Blocks

These may be supplied loose or strapped in unit loads and stored on raised timber pallets.Facing and coloured bricks should be covered to prevent contamination.

tarpaulin covering

cement storageweather

boarded shieldwithout

windowsConstruction Practice for Technician & Diploma Students -Volume One

ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 14Timber and Joinery

These should be stored horizontally and covered and provision made for air circulation.

Timber sizes should be kept separately and raised off the ground to preventcontamination.Drainage pipes

Should be supplied loose or strapped on timber pallets. It should be stored horizontallywith the ends reversed in alternate rolls.Location of plants

Plants must be placed at the most convenient and strategic points so that maximumbenefit could be achieved from their use. Points to consider:i. Headlights should be set up truly horizontalii. They should be securely fixed to a firm and solid base.iii. Cranes should be positioned so that they are able to reach all materials that need

to be hoisted; e.g. cement, aggregate etc.iv. Mixers and mortar pans should be specially sited to keep the distance to wheeling


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concrete or mortar as short as possible.v. Batching plants should be set up in a central position on the site to be readilyaccessible for Lorries to discharge aggregates etc appropriately.Factors to be considered when allocating plants on site

1. The availability of space

2. Working room requirements3. Mobility on site4. Servicing requirementsProvision for workers welfare and safety on site

It is essential to have the interest of all workers on site and to provide the best facilitiesfor their upkeep. Advantages from such provisions may include1. It reduces pilfering2. It serves as an incentive to the operatives3. Boost workers morale

4. Increases productivity

Construction Practice for Technician & Diploma Students -Volume OneANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 15Welfare and safety provisions include:1. Notices and fees to local authorities this include fees for water supply, publicservices and all other fees which may be demandable by the local authority.2. Watching and lighting to provide all requisite day and night watching.3. Maintenance of public and private roads there should be no damage to roadways,footpaths and all other properties.4. Water for the works the contractor must supply water for the site andresponsible for the protection of meters and cocks.

5. Lighting and power artificial lighting and power must be provided on the site forall personnel, including subcontractors and nominated subcontractors.Difficulties encountered when working in bad weather

Rain, high winds, low temperatures, poor daylight levels are some of the weather effectsthat can seriously affect construction activities.The worse effects obviously occur when more than one of these occurs simultaneously.

Shelter is required for the men during bad weather and somewhere to deposit the clothesnot worn during working hours.Lessening of difficulties in hot weather

1. In very hot weather, the freshly laid concrete should be shielded from the direct

sun until seven days to prevent rapid evaporation due to temperature, relativehumidity and wind.

2. Mixing water and the materials must be kept as cool as possible.3. Aggregate should be protected from the sun and sprayed with water to cool downimmediately.Lessening of difficulties in cold weather

1. All aggregate should be pre-heated by perforated steam pipes to prevent the

attack of frost.


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2. Mixing water must be heated to a temperature not exceeding 80C with a watercement ratio of 0.5.3. Concrete must be cured for longer periods due to the fact that low temperatures

retard concrete hardening and strength gain.Construction Practice for Technician & Diploma Students -Volume One

ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 164. Additional Portland cement, high curing temperatures (steam curing), high earlystrength cement and other known methods may be employed to obtain high-earlystrength.Site & Soil Investigation

The basic objective of site investigation is to collect systematically and to record all thenecessary data which will be required in the design of the proposed work and their

construction. Site investigation is thus all embracing, taking into account such factors astopography, location of existing services, means of access and any local restrictions.Soil Investigation specifically relates to the subsoil beneath the site under investigation

and could be part of or separate from the site investigation. It is usually a means ofobtaining data regarding properties and characteristics of sub-soils by providing samplesfor testing or providing a means of access for visual inspection.Methods of soil classification

i. Physical propertiesii. Geological originiii. Chemical composition

iv. Particle size distributionGenerally soils are defined as coarse - grained or fine grained each resulting in differentproperties.

Coarse grained soilsThese include sands and gravels having a low proportion of voids, negligible cohesion when

dry, high permeability and slight compressibility which takes place almost immediately uponthe application of load.Fine grained soils

These include cohesive silts and clays having a high proportion of voids, high cohesion, verylow permeability and high compressibility which takes place slowly over a long period time.

There is however several soils which can be described between these two extremes andare divided into particle size as follows:1. Clay particles less than 0.002mm

2. Silt particles between 0.002 and 0.06mmConstruction Practice for Technician & Diploma Students -Volume One

ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 173. Sand particles between 0.06 and 2mm4. Gravel particles between 2 and 60mm

5. Cobbles between 60 and 200mmPurpose of Soil Investigation

a. Determine the suitability of the site for the proposed project.


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b. Determine an adequate and economic foundation designc. Determine the difficulties, which arise during the construction process and period.d. Determine the occurrence and or cause of all changes in subsoil conditions.Factors Affecting Method or Choice of Soil Investigation

a. The size of the contract

b. Type of proposed foundationc. Type of sample requiredd. Type of subsoil to be encounteredMain methods of soil investigation

The methods of soil investigation areTrial pits small contracts where foundation depths are not likely to exceed 3.0mBore holes- - medium to large contracts with foundations up to 30.0m depth.Trial PitPrimarily to obtain subsoil sample for identification, ascertaining the subsoil

characteristics and properties. Trial pits and auger bore holes may also be used to

establish the presence of any geological fault and upper or lower limit of the water table.Trial pit can also be used to expose and /or locate underground services.Construction Practice for Technician & Diploma Students -Volume One

ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 18The trial holes are used purposely to:1. Know the thickness of each layer of the subsoil2. Know the composition of each stratum

3. Know the size of various particles of which the subsoil is composed in each stratum4. The condition of each stratum5. The water table level

6. The quantity of water below ground levelDisadvantagesi. Difficult to operate in high water tables and very loose soilsii. There is the need to provide for pumps for and timbering to provide dry land

Bore holeThese are carried out using either a hand auger (shallow bore hole) or mechanical auger(deep bore hole) to determine the suitability of a particular type of soil for a project. Ashell boring tool consist of a cylindrical steel shell which is dropped into the soil causingsoil to be forced into the cylinder either by friction in the case of cohesive soil ornonreturn

flap in the case of non-cohesive soil.The diameter of the samples obtained varies from 100mm 200mm according to themethod employed in extracting the sample. Undisturbed soil samples can be obtained fromConstruction Practice for Technician & Diploma Students -Volume One

ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 19cohesive soils 450mm long x 100mm diameter sampling tubes which are driven into the soilto collect the sample within itself, upon removal the tube is capped, labeled and sent to


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hardwood peg(top levelequals ground level).concreteConstruction Practice for Technician & Diploma Students -Volume One


Transferring levelsThe level of the site datum can be transferred to other parts of the site in several ways.One method is using the straight edge and the spirit level. The straight edge and thespirit level must be reversed in the next move to cancel out minor errors that may occur.Requirements of setting out:1. Should be in the correct position

2. Be at the correct level3. Be erected verticallyground line3.0m straigt edge

straight edge& spiritlevel reverseddatum pegpegtransferring levels-straight edge spirit level methodConstruction Practice for Technician & Diploma Students -Volume One

ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 22Sequence of operationNote: all setting out is done from a building line.

1. Drive in pegs on the side boundary at the correct distance from and parallel to the

centre line of the road2. Strain a line between two nails placed at the centre of the pegs

3. Drive two pegs C and D along the building line to indicate the front corners of thebuilding.4. Set out lines at right angles to peg C and D and establish pegs E and F. Drive nailsat the centres of the pegs and stretch lines between the four pegs.

5. Measure along lines CE and DF to establish pegs G and H in the far corners of thebuilding.6. Check diagonals CH and DGNote:

Base line is the line on which the building commencesBuilding line is the an imaginary line drawn from the centre of the road to the baseline

trenchwidth

wallwidth


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saw kerfarrangement for

a corner profileConstruction Practice for Technician & Diploma Students -Volume One

ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 23Frontage line is the line in front of which no other development is permitted by thelocal authority (and can be the building line or the base line).

Setting out CurvesTo set out circular shape the easiest method is to determine the centre or striking pointof the curve. Then a trammel or measuring tape is used to mark out the curve by securing

the trammel at the centre point and swinging around in an arc.Using template

1. This method is applicable if the radius of the curve is short.2. Mark out the chord AB and rise CD3. Fix nails at points A B and C.4. Nail battens together so that the first batten touches points A and C and the

second points B and C5. Nail the spreader across the two battens6. Draw the curve by moving the frame so that it keeps in contact with points A and Bwith a pencil at the intersection.Construction Practice for Technician & Diploma Students -Volume One

ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 24Setting out right angles3:4:5 method

1. Mark out a triangle of sides 3:4:5

2. Measure three and four units respectively on the front and side lines3. Position the side lines so that the distance between the two marked points is five

units.Builders square


ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 251. Using a large builders square set it up on pickings so that one leg is against the building line.2. Position the side line so that it runs parallel to the other leg of the square.3. Read off the right angle at the corner.

3:4:5 methodbuilders square methodUsing the site square

1. Set out the base or building line with pegs at the required distanceConstruction Practice for Technician & Diploma Students -Volume One

ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 262. Set the site square at the head of nail at the peg marking the corner to be set out


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3. Sight onto the nail in the next peg along the base line and obtain the dead onposition4. Measure the required distance approximately at right angles to the peg from the

peg from which the instrument is set up. Signalthe assistant to move pe sidewaysuntil it is on spot.

5. Place a nail at the top of the peg ensuring that the nail is at the centre and thatthe distance is the exact required.6. Repeat the operations on all pegs to set out the corners of the structure.Setting out acute angles

To setout 451. Set out right anles using any known methods

2. Measure equal lenths from the vertex topoints B and C3. Measure carefully halfway the length BC4. Pull a line from A through the mid point of BC and this forms 45 to either of the lines forming the right angles.Construction Practice for Technician & Diploma Students -Volume One

ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 27To setout 60Measure any convenient distance between points A and B

Hammer in pegs at these pointsA third point C is driven in from both points A and BPull lines from peg A through peg B and from peg A through peg C

The two lines will form 60When this angle is halved 30, 15 and 7.5 can be set outConstruction Practice for Technician & Diploma Students -Volume One

ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 28Timbering to trenches

Timbering is the method used to support the ground when excavating is done.Factors to consider when timbering

1. The nature of the soil2. The pressure to be supported3. The depth of cutting4. The water table levelPurpose of timbering

To prevent the sides of the trench from collapsing

To safeguard the operatives working in the trenchTo save excessive excavation as in battered trenchesCauses of collapse of timbering

1. Variation of the bearing pressure2. Changes of angle of repose due to moisture content differences

3. Failure due to heavy loads placed near the edges of the trench4. Overloading timbering membersMethods of support


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1. Timbering2. Sheet piling3. Battering

4. Cofferdams5. Retaining walls

6. CaissonSafety requirements1. Must be inspected by competent persons2. Timbering must be done as the work proceeds3. Suitable barriers should be providedConstruction Practice for Technician & Diploma Students -Volume One

ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 29STAIRS

A stair is a series of steps leading from floor to floor, floor to landing or landing tolanding.

A stair case or stair way is the complete system of treads, risers, strings, balustrades,and other component parts in one or more successive flights of stairs.The space occupied by a staircase is called a stairwell. The vertical distance between thefloors served by a staircase described as the lift.Function

The primary functions of any stairway are:1. To provide the movement of people and goods from one floor level to another

2. To provide a suitable means of escape in case of fireTypes of stairs

i. Straight flight

ii. Dogleg or half space landingiii. Open well

iv. Geometricalv. Spiralvi. HelicalStraight flight

This the simplest form of stair and consists of a straight continuous flight or run of

parallel steps.Dogleg

A dogleg or half turn stair has one flight rising to an intermediate half-space landing, with

the second flight travelling in the opposite direction to the first.Open-well or Open newel

This stair contains a central well with newels at each change of direction and two or moreflights of steps around the outside of the well.Construction Practice for Technician & Diploma Students -Volume One

ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 30Geometrical stair

This is a stair which takes the form of a spiral with the face of the steps radiating from


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the centre of a circle which forms the plan of the outer string and incorporates an openwell.Spiral stair

This is a form of geometrical stair without a well.Helical stair

This is a stair which contains a helix round a central void.Regulations and Requirements

1. The pitch of a private stairway must not be more than 42. 2. The pitch of a common stairway must not be more than 38. 3. The rise per step of a common stairway must not be more than 190mm.4. Maximum rise per step should be 220mm.

5. Minimum going should not be less than 225mm.6. Twice the rise plus the going shall not be less than 550mm and not more than700mm. (2R + G = 550 -700mm).7. The minimum headroom shall not be less than 2m, measured vertically the pitch line.

8. The nosing of any tread in an open riser stair shall overlap the back edge of thetread below not less than 16mm.9. Stairs with open risers shall be constructed such that the spaces between the openrisers do not permit the passage of a 100mm sphere.

10. A stairway should not have more than 16 risers in a flight.Construction Practice for Technician & Diploma Students -Volume One

ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 31quarter - space landingopen newel stairdog-leg stair

landing between two straightflights (fly landing)Straight flight Dog-leg Open Well Geometricalsectional elevationPre- Cast Concrete Spandrel Stair

(triangular section)Geometrical

Up


ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 32Terms

1) Tread 2)Riser 3) Nosing 4)Going 5)Rise 6)Margin

7) Closed String 8) Cut (open string) 9) Newel 10) Bearer11) Brackets 12) Trimmer 13) Blocks 14) Handrail 15) Baluster 16) Wedges

Spiral (helical) StairPlanREGULATIONS FOR COMMON STAIRWAYgoing not less than 225mmrise not less than 190mm


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38Pitch Line



REGULATIONS FOR PRIVATE STAIRWAYgoing not less than 212mmrise not less than 200mmPitch LineGlue Block16mm Riser

HousedScotiaMETHOD OF FORMING STEPS22mm Tread9mm plywood

RiserGlue Block

HOUSED RISERNewel Fixinggalvanisedsteel dowelgrouted intoconcrete floorNewel


ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 34Guarding of stairwaySetting out the stairs

Assume a lift or total rise of 2400mmAssume a travel or total going of 2925mmAssume 14 risers

Thus number of treads = 14 - 1 = 13Construction Practice for Technician & Diploma Students -Volume One

ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 35Thus: rise = lift/ total rise = 2.400 = 172mm

Number of risers 14Going = travel/total going 2.950 = 225mmNumber of treads 13

Check: 2R + G = 550 - 700mm; 2(172) + 225 = 344 + 225 = 569mm, thus the stair issatisfactory.Factors affecting the design of stairs

1. Purpose or use of the stair2. Size and shape of the stairwell3. Economic factors (type of construction, cost, material type etc.)4. Total height of the buildingDefect in stairs


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1. Poor fixing of newels and top nosings2. Flights not rigidly fixed3. Handrails not sanded smooth

4. Creaking of stairs resulting from poor securing of treads and risersUnprotected stairs, damage after installation and loosened items such as Disadvantages

of timber stair1. The main disadvantage is that it will help to spread fire in case of an outbreak.2. Few timbers are resistant to decay or insect attack, thus for a prolonged life span,

the timber should be preserved which may automatically increase the cost fconstruction.3. Difficulty in the selection of good quality timberAdvantages of concrete stair

1. Non combustible2. Strong as compared to timber

3. Hard wearing

4. Obtained in in-situ or pre-cast for ready installation.Disadvantages of tapered steps


ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 361. Hazard to the aged and the very young, due to the very small tread length at ornear the newel post.2. Difficult to carpet3. Difficult to negotiate with furniture4. Have little or no aesthetic appeal5. Expensive to construct

Pre-cast concrete stair constructionBasically there are two methods of fixing stairs into walls:i. as the work proceedsii. after the work has been completedFixing after completion of the wall

1. Set out the position of the stairway as the wall proceeds to ensure the correctplacement of the sand courses.2. Remove the sand courses, brush out the indents and dampen the wall3. Use a height rod to set out position of stair between two floors this should havethe number of steps required marked on it

4. Measure the total going of the steps and divide into the number of steps5. Use riser and tread gauges to allow for ease of checking6. Bed the first step in a cement sand mortar (1:2) across the width of the stair, level

in both directions, check for height and build into the wall7. Wedge the steps at both ends and level the treads8. Lay a straight edge against the nosings of the stair to check for accuracy9. Use a line to check the alignment of the steps at their free endsFixing the steps as the work proceeds


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1. Set out the position of the stairway as the wall proceeds ( no provision of sandcourses)2. Use a height rod to set out position of stair between two floors this should have

the number of steps required marked on it3. Measure the total going of the steps and divide into the number of steps

4. Use riser and tread gauges to allow for ease of checking5. Bed the first step in a cement sand mortar across the width of the stair, level inboth directions, check for heightConstruction Practice for Technician & Diploma Students -Volume One

ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 376. Lay a straight edge against the nosings of the stair to check for accuracy

7. Use a line to check the alignment of the steps at their free ends8. If the steps are cantilevered a temporary support must be providednot less than 16mm

Square for determining

position of the step ( gauge)OPEN RISER STAIR WAY

upper part of step

reinforcedMethods of checking the accuracy of the position of the steps


ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 38waistcut string

treads fixedto string

open riser stairNewelHandrailStringFitting Handrail & stringto newel in timber stair

Metal Bracket to wallHandrail screwed throughbracket to plugHandrail plugged screwedFixing handrails

molten lead caulked intomortice around standardEnd of handrailflattened and bolted toside of concrete stairMetal standard ofbalustradecement pointing


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standard ragged withsaw cutsnut & washernut & washerbaluster bolted tread or

landingfixng metal standard toconcrete stepsConstruction Practice for Technician & Diploma Students -Volume One

ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 39tension lapstarter barsdistribution barsmain barsstair waist

distribution barsIn-situ reinforced concrete stair details

Straight egde to

check nosingcleatstrutjoist

sole platewedgescleat

margin piecesoffit boardstrutpropscleat

strutsouter cut stringto both edgesbracingConstruction Practice for Technician & Diploma Students -Volume One

ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 40wedgesstring

scotia mouldnosingblocks

riser


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treadline of nosingsection through a string

handrailtop rail grooved

into handrailplywood panelsbottom railcappingstringpanelled balustradeB

BA

A


ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 41DOORS

A door is a solid barrier fixed in a doorway or opening in a wall or partition to hinge, pivotor slide open to close for access to and from buildings and between rooms, compartment,corridors, landings and stairs.A door is classified by the way it is positioned in a building, by their function or their

method of construction. The recommended size of a door opening is 900mm x 2100mm.this gives a door size of 800 x 2000in both width and height.Functional RequirementsThe primary function of a door is the means of access. The functional requirements of a

door when closed area. Privacyb. Strengthc. Stability

d. Weather resistancee. Durability or freedom from maintenancef. Fire securityg. Resistance to the passage of heath. Resistance to the passage of soundi. Exclusion of wind and rain (external door)

Selection of DoorsThe factors affecting the choice of doors are:

a. Position in the buildingb. The order of priorityc. AppearanceThe order of priority of the performance requirements of a door are:i. Weather exclusion


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ii. Securityiii. Fireiv. Thermal/sound insulation

v. Privacyvi. Durability

vii. Method of operationConstruction Practice for Technician & Diploma Students -Volume One

ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 42The appearance of a domestic bathroom door is of little importance, whereas the doors tothe office of a Managing Director should create a suitable impression on those entering.External doors

These are used to close the access to the internal of a building and provide a means ofsecurity. They are thicker and more robust in design than internal doors.Internal doors

These are used to close through internal walls within the building, partitions etc. they are

made thinner than their external counterparts since weather protection is no longer arequirement.Classification (types)Battened doors (match boarded doors) - ledge and batten doors, ledge, brace and battendoors and frame ledge brace and batten doors.1. Panel doors2. Glazed doors

3. Flush doors4. Purpose made doorsLedge and batten doors

The face of the door is made from tongue and groove boarding which has edge chamfersto one or both faces, forming a vee joint between consecutive boards. Normally threehorizontal members called ledges, clamp the boards together making it a non standardform of a door. It is cheap to construct but has a disadvantage of dropping at the closing

edge, thus pulling the door out of square. its use is limited to buildings such as sheds,outhouses, and small units like trap doors.Ledge brace and batten doorsThis is a standard battened door in which braces are incorporated to resist the tendencyof the door to drop out of square. The braces are fixed between the ledges so that they

are parallel to one another and slope toward the hanging edge.Construction Practice for Technician & Diploma Students -Volume One

ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 43Frame ledge brace and batten doors

Another standard door in which mortise and tenon frame surrounds the match boardedpanel, giving the door added rigidity. When the doors are wider, the braces become too lowto be of value as an effective restraint and it must therefore be framed as a diagonalbetween the top and bottom rails.


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Treatment to doors in transitA door irrespective of the soundness of its construction will deteriorate if improperlytreated during transportation, storage and after hanging.

framed ledgedbrace & batten door

ledged brace &batten doorledged &batten doorledgematch board

top railbracestile

bottom rail

middle railhanging edge1,2,3,or 4 panelled doorstop railplywood or glazedpanelstilebottom railmiddle railskeletonframinglightweightcore filling

plywood facingedge lippingflush doorConstruction Practice for Technician & Diploma Students -Volume One

ANSAH NANA BENYI CIVIL ENGINEERING TECHNOLOGY Page 44Treatment1. It should receive wood priming coat of paint before or immediately after delivery,

2. It should be stored in the dry and flat position so that it does not twist before and

immediately after delivery3. It should also receive finishing coat of paint as soon as practicable after hanging4. Finished doors should be wrapped in building paper or polythene sheet to prevent

damage to the finished doorpurpose made doorstop railplywood or glazed


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panelstilebottom railmiddle railpurpose made doors

top railstilebottom railintermediate railfrieze railsolid raised panel

Construction Practice 1 for Technician

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