School of the Built Environment

BUILDING REFURBISHMENT & MAINTENANCE

FURTHER ASPECTS OF

MODERNISATION

School of the Built Environment

OVERVIEW

• Why commercial modernisation

• Typical external improvements

• Typical internal improvements

• Over-roofing

• Over-cladding

• Re-cladding

School of the Built Environment

LEARNING OUTCOMES

1. Understand the benefits and limitations of

prescribing improvements for commercial and

industrial refurbishment schemes.

2. Identify the measures for improving the technical

performance of a commercial building’s main

elements.

3. Appreciate the design requirements of major

improvements such as over-roofing and over`-

cladding.

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Reasons for CommercialRefurbishment

• To improve the building’s aesthetics

• To improve the lettable floor area

• To satisfy changes in regulations/legislation

• To cater for a change in use

• To upgrade services

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COMMERCIAL REFURB. RATIONALE

• Building deficiency: requires attention due to poor condition or amenity

• Changing work patterns: changes in the way in which the bldg is used.

• Market requirements: Bldg no longer economical due to inefficient heating

system or unlettable

• Enhancing company profile: major org can have regular changes or

images to reflect corporate color & images

• Improving indoor air quality

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TYPICAL EXTERNAL IMPROVEMENTS

• Envelope upgrade– Re-roofing: full or partial removal & replace with new. Normally involve thermal upgrade.

– Over-roofing: Install complete new roof over the existing roof.

– Over cladding: New cladding to the ext face of the outer wall. Improve aesthetics,

thermal performance or weather resistance.

– Re-cladding: Removal or overlaying the extg external cladding with new.

• Flood lighting: Intro high powered ext lighting for safety or security.

• New Canopies: provide extg weather protection over access points.

• Revolving Doors: To replace conventional door to reduce heat losses & draughts &

improve security.

• Bollards & Crash Barriers: Install at ext ext perimeter to improve safety, alter

pedestrian flow around building to reduce risk

• Ramps & Pavings: improve amenity around bldg or by regulations.

• Landscaping: improve security & privacy, improve ground drainage & risk of flooding

School of the Built Environment

TYPICAL INTERNAL IMPROVEMENTS

• Refit toilets: renewing units & appliances

• Refit staff facilities: improve staff

welfare ie. Floor coverings, furniture, etc

• Refit services: Electrical wiring, elect

appliances; cold & hot water supply, etc

– HVAC: provide better thermal comfort and

acceptable indoor air quality

– Lighting: energy savings

• Renew– Entrances: doors, shutters , glazing

– Floor Finishes: Vinyl, carpeting,

laminates

– Wall Finishes: paper, carpeting, paint

– Ceilings: suspended tiling, plaster boards

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PYP

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OVER-ROOFING

• Reasons – failure of existing flat roof

• Options– Recover/Replace Existing Flat/Pitched Roof: this option only

involve upgrading to the weather protection, ie the extg tiles, slates or felt are replaced with new.

– New Pitched Roof: with entirely new members

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OVER-ROOFING

• New roof structure methods– Portal/Moment-Resisting Frames

– Trusses (With or Without Purlins/Attic/Long-span)

– Propped Struts (eg, “AshJack” or “SpeedDeck”)

– Purlins and Rafters

• Requirements – structural integrity / access /

building services / access to roof

• Indicative costs (£50/m2 to £200/m2)

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OVER-ROOFING STRUCTURE

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OVER-ROOFING CONSIDERATIONS

• Structure & condition of existing roof & wall

• Extent & location of services

• Need for fire compartmentation

• Access around building (crane, scaffolding

and storage)

• Disruption to tenants

• Programming of works where wall

over cladding is also undertaken

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SERVICES

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FIRE COMPARTMENTATION

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ACCESS + STORAGE

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Another Type of OVER-ROOFING

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Claddings

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Over-cladding - Improve aesthetics, thermal performance or weather resistance

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OVERCLADDING

• REQUIREMENTS– Protection: against wind, wind-driven rain, impact & lightning

– Appearance: acceptable appearance keeping

with convention & surrounding env.

– Durability: Life span at least equal to the overclad structure.

– Insulation: incorporate thermal insulation

(to reduce heat loss & sound transmission)

• FAÇADE DESIGN– Style

– Colour

– Texture

• MATERIALS– Frame: stainless steel, Al, Composite plastics, timber

– Glazing: strengthened, coloured, etc

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TYPES OF OVERCLADDING

• RAINCOAT SYSTEMS

– Types:

– - Insulated Render: thermal insulation

fixed to the substrate over which is applied a normal or chemical render.

– - Insulated Brick Slip: thermal insulation fixed to the

substrate over which is fixed with a thin brick and thereafter grouted.

– Suitability: low rise dwellings where finishes are

rendered and brick are used

– Precautions: Expanded insulation can increase risk

of fire spread> must be properly bonded to prevent detachment.

School of the Built Environment

TYPES OF OVERCLADDING

• RAINSCREENS SYSTEMS

– Types:

– - Drained and Back-Vented

Fiber cement panels(or metal composite) are

considered a drained/back ventilated rainscreen.

This is a panelled wall system installed to framing

using clips that hold the panels away from the

structure. The clips provide different depths of air

space depending on the designer’s preference and

moisture is released through this air layer. Fiber

cement panels are installed over a water track with

weep holes. If it is a metal composite, when

condensation or penetrating rain water can drain

down the back of the sheeting where it is directed

outside at the regular flashing location.

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RAINSCREEN CLADDING PRINCIPLES

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EXAMPLES OF RAINSCREEN

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TYPES OF OVERCLADDING

• Pressure Equalised SystemThis rainscreen cladding system is cavity compartmentalised to control pressure and stop the spread of fire through the building.

This system allows wind to blow in and behind the rainscreen panels, equalising the pressure, resulting in a very low wind load on the panels themselves. Design in accordance to BS6399-2-199.� Cavities are compartmentalized� Openings calculated to allow rapid ingress and egress of air� Water ingress reduced by ‘equalization’ of internal and external pressures

(pressure moderated system)� Drained above compartment levels� Suited to tall areas of rainscreen� Design intensive� High pressures generated at corners require that the centres of vertical

compartments are reduced.

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TYPES OF OVERCLADDING

• Pressure Equalised System

– Suitability: medium or high rise dwellings where finishes are

rendered and brick are used

– Precautions: enclosed ventilated cavity can act as

– a chimney directing flame and fire up the bldg facade

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Fire Stops in Cladding

Over cladding – fire break detail

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RE-CLADDING

• REASONS

– Premature Degradation: fails prematurely or reached the end of its service

life.

– Damage: result of storm, impact or vandal.

• PROBLEMS

– Approvals: From P&BC where major refb required.

– Fixings: Fixing to a new structural points on bldg.

Assessment of structural loading

– Finish: required to match existing or surrounding.

• OPTIONS

– Curtain Walling

– Special Cladding