Building pathology Flashcards

1
Q

Can you give me some typical defects for Victorian properties?

A
  • Lintel failure.
  • Penetrating damp.
  • Spalling brickwork
  • Slate roofs (nail sickness).
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2
Q

Can you give me some typical defects for Georgian properties?

A
  • Slate roof issues (nail sickness).
  • Penetrating damp.
  • Roof spread (low pitch, no trusses).
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3
Q

What are the BRE Digests for dry rot and wet rot?

A

Dry rot: BRE Digest 299.
Wet rot: BRE Digest 345.

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4
Q

When do the humidity levels begin for dry rot and wet rot?

A

Dry rot: 20%.
Wet rot: 50%.

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5
Q

What’s the difference between dry rot and wet rot?

A
  • Dry rot: 20%, wet rot 50%.
  • Dry rot spreads easier (masonry and plaster).
  • Wet rot doesn’t spread easily (timber).
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6
Q

How are you able to determine whether a property had dry rot on site?

A
  • Forms on masonry or timber.
  • White fluffy (cotton-like).
  • Forms strands.
  • Brittle.
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7
Q

How are you able to determine whether a property had wet rot on site?

A
  • Stays within areas of moisture.
  • Timber becomes darker and spongey.
  • Doesn’t form strands.
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8
Q

What is the risk of dry/wet rot if not dealt with properly?

A
  • Weakens timber (structural issues).
  • Health issues.
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9
Q

How would you deal with dry rot/wet rot?

A
  • Find source of moisture.
  • Remove rot 500mm past fungus.
  • Treat.
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10
Q

What BRE Digest is there for assessing cracks?

A

BRE Digest 251.

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11
Q

What is the difference between subsidence, heave and settlement?

A

Subsidence: Soil beneath sinks.
Heave: Upward movement of soil from an increase in moisture levels, which causes clay soils to expand.
Settlement: Downward movement of the ground (caused by weight of the building).

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12
Q

Can you give me some examples of deleterious materials?

A
  • 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).]
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13
Q

Can you tell me the different types of asbestos?

A

Chrysotile (white).
Amosite (brown).
Crocidolite (blue) - thin needle like.

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14
Q

What is carbonation?

A

CO² reaction that makes concrete more acidic.

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15
Q

What is the effect of carbonation?

A

Rebar begins to expand as it corrodes which casues the concete to spall.

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16
Q

What is the issue with RAAC?

A
  • Lack of coarse aggregate (weak).
  • Porous (weakens the concrete).
  • Deteriorates over time.
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17
Q

What is the issue with HAC?

A

Loss of strength over time through ‘conversion’, vulnerable to chemical attack.

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18
Q

How do you identify RAAC and HAC?

A

RAAC: No gravel, bubble appearance internally.
HAC: surface deterioration, chemical testing.

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19
Q

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?

A
  • Calcium carbide test.
  • Damp meter [indicative result as salts in masonry reduce accuracy].
20
Q

What causes rising damp and what are the signs?

A

Moisture rising though porous materials.
[Identified by tide marks, salt deposits.]

21
Q

What causes wall tie failure?
How is it identified?

A
  • Corrosion of wall ties.
  • Cracking to a course around 5 bricks wide.
22
Q

Windsor Walk, London - What guidance can you use to assess the severity of cracks?

A

BRE Digest 251.

23
Q

What is the relevant guidance note for brickwork repairs?

A

BRE Good Repair Guide 3.

24
Q

Can you give me an example of where you have used crack stitching previously?

A

17 Bowling Green Lane.

25
Q

Windsor Walk - The helical bars – did you design these?
What was the warranty for this work?

A
  • No I contacted a specialist contractor who undertook the designs and carried out the works.
  • 10 year guarantee.
26
Q

What are some common causes of cracking in brickwork?

A
  • Frost damage.
  • Arch failure.
  • Settlement.
27
Q

You carry out a survey of an industrial building constructed in the 1970’s. What type of defects might you come across?

A
  • Asbestos fibre cement roof sheets.
  • HAC: process called conversion occurs which weakens the structure (1950s-70s) [identified by surface deterioration and chemical testing].
  • Roof leaks.
28
Q

Bircholt Road, Maidstone - How did you identify composite cladding panels?

A

Smaller profile to the cladding vs built up system and if you push it its firmer than built up cladding.

29
Q

What is the Loss Prevention Certification Board (LPCB)?

A

A third-party organisation that sets standards for fire and security products.

30
Q

What would you have done if the panels hadn’t been LPCB approved?

A

Advise the client to discuss this with their insurers to assess the implications of purchasing a building with non-LPCB approved cladding.

31
Q

Windsor Walk/18-20 Tileyard Road - What flat roof tests did you undertake aside from visual inspections?

A

Damp meter on timber structure [15-20% indicates moisture is present could lead to issues, over 20% considered high].

32
Q

What ventilation would you expect to see in a pitched roof?

A

Eaves ventilation.

33
Q

Note: Damp meter: WME (Wood Moisture Equivalent); calibrated for timber; foil backed plasterboard can give false readings.

34
Q

You mention having a knowledge of testing methods, including damp meters. What type of damp meter is calibrated to timber?
What other types are there?

A
  • Pin type (electrical resistance).
  • Pinless (electromagnetic waves).
35
Q

What percentage WME would indicate damp in softwood timber?

36
Q

Record Street, Bermondsey cut edge corrosion – a) what remediation did you recommend?
b) How did you cost it?
c) What additional things were there to consider?

A

a) Clean, prime (corrosion inhibitor), seal (tape), coat (polyurethane waterproofing).
b) BCIS.
c) Health and safety – edge protection or mansafe system.

37
Q

Anchorage House, London – Draw the gutter detail how it should have been.

A

[Show the membrane to overlap the extension and gutter].

38
Q

Anchorage House, London – Assuming your hypothesis on the water ingress was correct, how would you rectify this?

A

Redress the membrane to ensure it lapped the extension and the gutter giving a continuous layer.

39
Q

What are the classifications of cracks in BRE Digest 251?

A

HFERES.
0 - Hairline: <0.1mm.
1 - Fine: up to 1mm.
2 - Easily filled: up to 5mm.
3 - Repairs: 5-15mm.
4 - Extensive: 15-25mm. Break out and replace.
5 - Structural: >25mm. Partial/complete rebuild.

40
Q

How would cracking form to a brickwork wall if there was subsidence below a building?
What about heave?

A
  • Subsidence: Wide top, narrow bottom.
  • Heave: Narrow top, wide bottom.
41
Q

What directions are the cracks typically for subsidence and heave?

A
  • Subsidence - diagonal.
  • Heave - vertical.
    [Both related to the direction that pressure is placed on the building.]
42
Q

Cut edge corrosion: Does aluminium corrode?

A

No - it’s a non-ferrous metal (magnet doesn’t attract).
[Ferrous metals contain iron]

43
Q

Building pathology - Anchorage House, London:
- Details of instruction (service, spec, contract value/claim amount etc)?
- Issues encountered?

A
  • Conditions survey.
  • Water ingress - new membrane had been installed which did not overlap the abutment between the new and old buildings or the inside of the gutter.
44
Q

Building pathology - Windsor Walk, London:
- Details of instruction (service, spec, contract value/claim amount etc)?
- Issues encountered?

A
  • Project.
  • £243k.
  • New ground floor, windows, brickwork repairs.
  • Refurb.
45
Q

What causes cracking to be wider at the top than at the bottom?

A
  • Subsidence.
  • Cracking wider at the bottom for heave.
    [Use hands]