Building Pathology Level 3 Flashcards
When was the Georgian period?
1714 - 1830
Typical Georgian foundation defects?
- Small thickness
- Minimal drainage
- Heave/subsidence
Typical wall defects Georgian
- Bricks - deterioration
- Rotten sash windows
- Repainting/Repointing issues
- Bowed brick walls
- Structural failure - Lack of lateral restraint
- Bay window roof problems
- Damp basements
- Load-bearing timber partitions
Georgian - causes of damp
Cracking, spalling brickwork
Condensation
Interstitial Condensation
Penetrating damp
Bridging DPC
Blocked air vents
Georgian - floor defects
Springy floor - decaying timber joists
Deflecting timbers
Georgian - roof defects
Leaks from roof
Roof structure defects
What is the Victorian period?
1830 - 1900
Victorian - foundation defects
- Subsidence (trees and drains)
- Differential movement (e.g where basements are present for part of the footprint)
- Bays (shallow footings)
Victorian - wall defects
- Book end effects
- Blocked air vents
- Removal of chimney breast
- Blown render
- Party walls unbonded to external wall (movement)
- Failing brick arch
- Wall tie failure
- Cement mortar used instead of lime mortar
- Water ingress
- Condensation
Victorian - floor defects
Rot - in timber beams
Water ingress - through corbels
Lack of ventilation
Victorian - Roof defects
Roof coverings (nail sickness, defective slates) Re-roofing - concrete tiles
Victorian - services defects
- Lead pipes
- Chimneys - use of chimney as gas appliance flue without liner
Victorian - How does damp occur?
- Penetrating - (RWG, splashback, flashings, chimney stack)
- Condensation
- Plumbing leak
- Salt contamination
- Rising damp
Mid-war houses - foundation depth
900mm for clay soil
Victorian - foundation depth
PROVIDE ANSWER
Post war housing - floor defects
Sulphate reaction of hardcore - expands and lifts slab
Types of non-trad housing
steel framed
timber framed
precast reinforced concrete construction
cast in-situ concrete construction
Steel framed systems
- designated as defective under the Housing Defects Act 1984
- primary concern is the potential for corrosion of the frame
- BISF
Timber frame (non -trad)
Defects are typically related to moisture and consequent timber decay.
Condensation also poses a risk
Cast in-situ concrete construction
Cast in-situ concrete systems were poured on-site into a timber ‘formwork’ called shuttering.
Can suffer corrosion
EXAMPLE
Precast reinforced concrete construction
Precast reinforced concrete systems were manufactured off-site, and ‘slotted together’ on-site
The primary concern in houses of concrete construction is carbonisation of the concrete, which can result in the reinforcing steels rusting, compromising the building’s structural integrity.
EXAMPLE
What is the Housing Defects Act 1984?
- introduced compensation for home-owners who had bought homes from local authorities
- a scheme of licensed repair grants offered to owners whose homes were identified as ‘Designated Defective
Non-trad defects
The main problem with non-traditional houses is the decay of the reinforcement bars in the walls
LPS
Large panel system (LPS) structures are like a ‘house of cards’ made of concrete panels. Floors and walls rest one upon the other, held together only by their own weight, until a lateral force is applied.
Cross wall
- a new design of houses was introduced which pared down the structural frame to just 2 walls.
- These 2 walls formed the party walls between terraced or semi-detached houses, and carried all the main loads to the foundations.
Issues with chimney stacks
Open flue
- Can lead to water ingress and vermin to enter (may cause blockages).
- Pots that are not in use should have a rain guard or ventilated inserts.
Closed flue
- When flue sealed for disused flues must include internal vents to prevent damp issues.
Mortar and tile flashing failure
Chimney breast removal
When chimney breast has been removed must be adequately supported.
- Gallows brackets
- A more secure alternative to brackets is a steel L-section beam that sits on the load-bearing walls of the house and supports the stack above.
What is capillary action?
Where liquids can travel – horizontally or vertically (against the force of gravity) in small spaces within materials
The movement is due to the surface tension that results when liquid or moisture is contained within very fine spaces or tubes