Defects by Era Flashcards
What age of building is typically susceptible to wall tie corrosion?
Cavity walls built between 1900 and 1940 are particularly prone to wall tie corrosion as the method for protecting them has not been standardised.
Galvanised wire ‘butterfly’ wall ties in the 1970s were known to have too thin a coat of zinc. Houses built in the early 1970s are particularly prone to wall tie failure.
When did cavity wall become common?
1920s
What are the width for solid and cavity wall respectively?
Solid - 230mm (9inches)
Cavity - 250mm (2 x 1002.5 mm wide bricks and 50mm cavity)
What common defects would you associate with buildings constructed pre-1900?
Alterations to loadbearing partitions (H)
Decay to sash windows (A)
Damp penetration through 225mm brick walls (A)
Defective rainwater goods (A)
Delamination of brick skins (A)
Original faced concealed behind later stone, brick or render finish (A)
Failed or lack of DPC (A)
Failure of brick arches or timber lintels
Insect attack within poorly ventilated and damp areas (A)
Lack of restraint to flank walls (O,H)
Lead lined parapet gutters (lead splitting, or poor sizing of outlets)
Lead water mains (A)
Notching floor joists for services (O, H)
Poor quality repairs to roofs and gutters (A)
Poor ventilation to roof voids (A)
Roof coverings replaced with heavier concrete coverings (H)
Differential settlement of bay windows (H)
Corrosion to filler joists in concrete floors constructed from concrete containing coke breeze (A)
Repairs made in cement mortar rather than lime (A)
What common defects would you associate with buildings constructed between 1900 and 1939?
Decay to sash windows (A)
Corroded galvanise steel windows (A)
Corroded rainwater goods (A)
Corrosion of roof nails (A)
Corrosion of steel frame from 1905 onwards i.e. Regent Street Disease (A)
Delamination of render to walls (A)
Lead water mains
Outdated electrical services (H)
Decay to timber joinery (A)
Use of boot lintels (A)
Use of mundic concrete (H)
Wall tie failure in cavity brickwork (A)
What common defects would you associate with buildings constructed between 1960’s and 1980’s?
Asbestos (A)
Aluminium sash windows (worn spring mechanism) (O)
Calcium chloride additive to concrete (A)
Calcium silicate bricks (prone to shrinkage; creamy colour) (A)
Cold bridging and condensation due to poor insulation standards (A). Especially around pre-cast lintels and balconies.
Cold flat roof construction (A). Often minimal insulation, ventilation, and vapour control layers. Most replaced by now.
Concrete (A). Poor quality, poorly compacted, lack of cover.
Concrete boot lintels (A).
Concrete frame (W, O)
- 1960s - with brick infill panels (frame shrinks, putting pressure on brickwork)
- 1970s – move to brick cladding with brick slips concealing frame. Detachment risk.
Corrugated asbestos cement sheet (W)
Cut edge corrosion of Plastisol covered sheet steel roofing (W)
External ceramic tiling/ mosaic tesserae (O) (delamination, adhesion failure, corrosion of metal lathing/ fixing screws, collapse)
Flat concrete floor slabs (O,W) (inappropriate design leading to collapse)
High Alumina Cement (O, W) Can have a brownish tinge. Loses strength with age.
Hollow clay pot floors (O). Common in the 60s. Concrete poured between pots as a topping. May have voidage. Lack of fire protection, durability, strength.
Lack of movement joints (A), especially in cement masonry walls.
Poor cavity tray details (A)
Reinforced aerated autoclaved planks (W, O)
Nickel sulphide inclusions causing spontaneous failure of toughened glass (mainly O)
Stramit roof decking (A). Very low resistance to water.
Use of reinforced concrete frames (A). Spalling, reinforcement corrosion, poor cover, poor quality concrete.
Wall ties (A). Poor galvanising standards. Corrosion causing horizontal cracks.
Woodwool and permanent shuttering (W, O) Poor compaction of concrete, grout loss leading to honeycombing. Loss of fire protection and potentially strength.
What common defects would you associate with buildings constructed between 1960’s and 1980’s?
Asbestos (A)
Aluminium sash windows (worn spring mechanism) (O)
Calcium chloride additive to concrete (A)
Calcium silicate bricks (prone to shrinkage; creamy colour) (A)
Cold bridging and condensation due to poor insulation standards (A). Especially around pre-cast lintels and balconies.
Cold flat roof construction (A). Often minimal insulation, ventilation, and vapour control layers. Most replaced by now.
Concrete (A). Poor quality, poorly compacted, lack of cover.
Concrete boot lintels (A).
Concrete frame (W, O)
- 1960s - with brick infill panels (frame shrinks, putting pressure on brickwork)
- 1970s – move to brick cladding with brick slips concealing frame. Detachment risk.
Corrugated asbestos cement sheet (W)
Cut edge corrosion of Plastisol covered sheet steel roofing (W)
External ceramic tiling/ mosaic tesserae (O) (delamination, adhesion failure, corrosion of metal lathing/ fixing screws, collapse)
Flat concrete floor slabs (O,W) (inappropriate design leading to collapse)
High Alumina Cement (O, W) Can have a brownish tinge. Loses strength with age.
Hollow clay pot floors (O). Common in the 60s. Concrete poured between pots as a topping. May have voidage. Lack of fire protection, durability, strength.
Lack of movement joints (A), especially in cement masonry walls.
Poor cavity tray details (A)
Reinforced aerated autoclaved planks (W, O)
Nickel sulphide inclusions causing spontaneous failure of toughened glass (mainly O)
Stramit roof decking (A). Very low resistance to water.
Use of reinforced concrete frames (A). Spalling, reinforcement corrosion, poor cover, poor quality concrete.
Wall ties (A). Poor galvanising standards. Corrosion causing horizontal cracks.
Woodwool and permanent shuttering (W, O) Poor compaction of concrete, grout loss leading to honeycombing. Loss of fire protection and potentially strength.
What common defects would you associate with buildings constructed between 1980’s to present?
External rainscreen systems and external wall insulation systems (A). Possible defects in fire stopping within cavity walls leading to fire spread. Water penetration.
Syphonic drainage systems (W). Early systems not reliable. Outlets vulnerable to blockage.
Nickel sulphide inclusions in toughened glass.
Composite panels (W). Use of expanded foam insulation and rigid polyurethane foam (PUR; pre-2000) can lead to rapid fire spread and explosive delamination.
Liquid roofing systems (A). Risk of failure due to poor surface preparation and detailing.
Indoor air quality (H). Greater use and reliance on mechanical ventilation and heat recovery. Failure to service or utilise equipment leads to risks.
Poor or inadequate fire stopping or cavity barriers (A).
What defects are common to buildings of all ages?
Over notching of floor joists (A).
Removal of chimney breasts (A).
Provision of insulation blocking ventilation paths (A)
Blocking of airbricks (A)
Removal of loadbearing walls (A)
Removal/ planting of trees (A)
When did cement mortars become more popular than lime mortar?
Post war years - 1950s onwards.
