Building Pathology Question Bank

Question 1

What are the typical defects associated with Victorian buildings?

Answer 1

There are a number of inherent defects:

• Shallow foundations leading to increased structural movement especially around bay windows which could cause differential settlement and subsidence.
• Lack of lateral restraint - the absence of connections between the external masonry walls and the internal floor/roof structure, allowing the walls to move outwards and bulge over time.
• Timber joists embedded in masonry walls are at risk of timber decay.
• Lack of damp-proof course prior to 1875 or failed physical damp-proof course leading to rising damp.
• Solid walls can increase of the risk of penetrating damp especially on exposed elevations.

There are a number of age-related defects:

• ‘Nail sickness’ whereby roof fixing nails corrode leading to an increased risk of slipped slates.
• Rusted cast iron rainwater goods leading to increased risk of damp.
• Erosion of sacrificial lime mortar.
  There are a number of alteration-related defects:
• Replacement of original slate tiles with cement - can cause overloading to the roof
• Repointing with cement mortar leading to brickwork spalling.
• Structurally weakened floor joists caused by over-notching leading to increased risk of bowing floor joists.
• Replacement of timber sash windows with uPVC windows with no trickle vents leading to increased risk of condensation damp.

Question 2

What are the typical defects associated with commercial buildings built within the 1960’s / 1970’s?

Answer 2

Commercial buildings from the 1960s and 1970s often have issues with poor insulation, leading to high energy costs and overheating in summer. Other common problems include asbestos exposure, structural weakness, and inadequate ventilation, potentially leading to condensation and mold growth.

Question 3

How would you identify dry rot?

Answer 3

• The wood darkens, shrinks and cracks in a cuboidal manner.
• The wood may crumble into fine powder.
• Fine white strands called hyphae which may extend across masonry.
• Large mass of white cotton-like growth called mycelium.
• Plate-shaped fruiting body which is rusty brown colour with white margins.
• Spores can be released from the fruiting body which appear as a red dust.

Question 4

How would you identify wet rot?

Answer 4

• The wood may darken or lighten dependent on the wet rot species.
• The wood cracks in a linear or cuboidal manner dependent on the wet rot species. Cracking will generally not be as deep as cracking found within dry rot.
• Brown or yellow strands called hyphae which doesn’t spread across masonry.
• Fruiting body which is olive brown with white margins although this is rare.

Question 5

What is dry rot commonly caused by?

Answer 5

Poor Ventilation
Condensation
Penetrating Damp
Leaking or defective roof
Leaking pipework

Question 6

What are the signs of Dry rot?

Answer 6

• The wood darkens, shrinks and cracks in a cuboidal manner.
• The wood may crumble into fine powder.
• Fine white strands (hypha) -spreading across the wood/masonry.
• Large mass of white cotton-like growth called mycelium.
• Plate-shaped/Mushroom fruiting body which is rusty brown colour with white margins.
• Spores can be released from the fruiting body which appear as a red dust.

Question 7

What documentation would you refer to, in order to aid your assessment of rot type?

Answer 7

BRE Digest 299: Dry Rot

BRE Digest 345: Wet Rot