Building pathology Flashcards
(53 cards)
Can you give me some typical defects for Victorian properties?
- Slate roofs (nail sickness).
- Penetrating damp (solid walls).
- Lintel failure.
- Spalling brickwork.
Can you give me some typical defects for Georgian properties?
- Slate roof issues (nail sickness).
- Penetrating damp.
- Roof spread (low pitch, no trusses).
What are the BRE Digests for dry rot and wet rot?
Dry rot: BRE Digest 299.
Wet rot: BRE Digest 345.
When do the humidity levels begin for dry rot and wet rot?
Dry rot: 20%.
Wet rot: 50%.
What’s the difference between dry rot and wet rot?
- Dry rot: 20%, wet rot 50%.
- Dry rot spreads aggressively (masonry and plaster).
- Wet rot doesn’t spread easily - needs constant source of moisture (timber).
How are you able to determine whether a property had dry rot on site?
- Forms on masonry or timber.
- White fluffy (cotton-like).
- Forms strands.
- Brittle wood, blistering paint.
How are you able to determine whether a property had wet rot on site?
- Timber becomes darker and spongey.
- Damp meter (above 20% WME).
- Stays within areas of moisture.
- Doesn’t form strands.
What is the risk of dry/wet rot if not dealt with properly?
- Weakens timber (structural issues).
- Insects: woodworm.
- Health issues.
How would you deal with dry rot/wet rot?
- Find source [leak, ventilation, rising damp - no moisture no rot].
- Remove rot half a metre past fungus [dry rot].
- Chemical treatment.
- Replace with treated timber and improve ventilation.
What BRE Digest is there for assessing cracks?
BRE Digest 251.
What is the difference between subsidence, heave and settlement?
- Subsidence: Soil beneath sinks.
- Heave: Upward movement - soil swells from increased moisture levels causing clay soils to expand.
- Settlement: Downward movement of the ground (caused by weight of the building).
Can you give me some examples of deleterious materials?
- Asbestos (1940s-2000).
- Lead paint (before 1970s, windows and doors).
- HAC (1950s-70s, public sector and industrial buildings).
- RAAC (1950s-90s, public sector buildings).
[- Woodwool slabs (1960s, warehouse and soffits - used as permanent formwork in my experience).]
Can you tell me the different types of asbestos and when they were banned?
Chrysotile (white) - 1999.
Amosite (brown) - 1985.
Crocidolite (blue) - thin needle like - 1985.
What is carbonation?
CO² reaction that makes concrete more acidic.
What is the effect of carbonation?
Rebar begins to expand as it corrodes which casues the concete to spall.
What is the issue with RAAC?
- Lack of coarse aggregate (weak).
- Porous (weakens the concrete).
- Deteriorates over time.
What is the issue with HAC?
- ‘Conversion’ process weakens concrete over time.
- Chemical attack [vulnerable to].
[HAC - CA = chemical attack]
How do you identify RAAC and HAC?
RAAC:
- No gravel.
- Bubble appearance internally.
HAC:
- Surface deterioration.
- Chemical testing.
If a property has been suffering from condensation for over a year and the mould is excessive on the surface of the wall and ceiling, how would you know if the subsurface, such as masonry, isn’t damp?
- Calcium carbide test.
- Damp meter [indicative result as salts in masonry reduce accuracy].
What causes rising damp and what are the signs?
- Moisture rising though porous materials.
- Tide marks, salt deposits.
What causes wall tie failure?
How is it identified?
- Corrosion of wall ties.
- Cracking to a course around 5 bricks wide.
Windsor Walk, London - What guidance can you use to assess the severity of cracks?
BRE Digest 251.
What is the relevant guidance note for brickwork repairs?
BRE Good Repair Guide 3.
Can you give me an example of where you have used crack stitching previously?
17 Bowling Green Lane.
