Building Pathology

Question 1

What are typical defects associated with modern methods of construction?

Answer 1

Timber frame - moisture ingress, rot, shrinkage, movement.

Cladding - inadequate sealing backing board, EPDM failure

Question 2

How would you inspect MMC projects?

Answer 2

• Manufacturers installation details
• junctions/interface
• fixings
• common defect areas
• check 3rd party accreditation
• competent installer
• ask colleagues
• safely! harness needed etc

Question 3

How would you identify rising damp?

Answer 3

Tidemarks and damp stains (horizontal) around 1m high on interior walls. Brown staining, peeling wallpaper, bubbling/flaking of plaster. Check outside to see if could be failed guttering etc

Question 4

What types of damp are there?

Answer 4

• Condensation. Damp from air
• Rising damp.
• Penetrating damp.
• Chemical damp. Salt contamination in plaster
• Damp from leaks i.e. plumbing

Question 5

What is the difference between dry rot and wet rot?

Answer 5

Wet rot requires higher mositure content. Wet rot tends to stay local to area of cause. Timber wet and spongy to touch, timber appears darker, local fungal growth

Dry rot spreads. Timber is dry and brittle, orange spore dust, rusty brown fruiting bodies.

Question 6

What are typical defects associated with cavity walls?

Answer 6

• wall tie damp penetration
• wall tie failure
• strength/stability ie buttressed walls
• penetrating damp

Question 7

How would you indetify cavity tie failure?

Answer 7

• Bowing walls
• small damp patches at spaces of ties
• Cracking

Question 8

What spacing should wall ties be at?

Answer 8

900mm wide x 450mm high. Doubled up around openings.

Question 9

What are the causes of render failure?

Answer 9

Poor bonding, incorrect mixture ratio, no movement joints, incorrect thickness

Question 10

How do you determine the materials used in general are suitable when inspecting?

Answer 10

Check manufacturers guidance & testing certificate. Check quality of workmanship

Question 11

What advice did you give about the cavity tray remedial

Answer 11

I advised that the tray be installed to cover the full width of the window and that stop ends were installed directing water out of the cavity

Question 12

What size pipes need fire stopping?

Answer 12

All pipes penetrating compartment wall should be fire stopped

Question 13

What are some common defects of concrete?

Answer 13

Carbonation - not enough cover to steel, can cause corrosion. Remove delaminated concrete, clean re bar and patch in new concrete

Chloride attack - spalled concrete, corrosion to steel. Remove all loose concrete, patch repair

Honeycombing - poor compaction, patch repair

Question 14

What are deleterious Materials?

Answer 14

• harmful to health, harmful to safety, pose a risk where they have been used. ACM cladding

Question 15

What testing of concrete can you carry out on site?

Answer 15

Slump test. Cone filled with concrete then removed and measured how much the concrete ‘slumps’