Timber decay

Question 1

What are the two types of wood-rotting fungi?

Answer 1

Wet rot and dry rot.

Question 2

What are the stages of dry rot?

Answer 2

1. Spores
2. Hyphae (thin cobweb like strands)
3. Mycelium (mass of hyphae)
4. Fruiting body

Question 3

What does the typical treatment of dry rot include?

Answer 3

1. Stripping off plaster 10 1m beyond the last identified point of infection.
2. Removal of visible indications of the fungi.
3. Cutting back of affected timbers to 500mm beyond the last recognised point of infection.
4. Surface spraying of a fungicide.
5. Remove the source.

Question 4

What are the benefits of repairing wet rotten timber with resin?

Answer 4

Less intrusive and reduction in the need for significant timber replacement.

This is particularly beneficial when dealing with historic buildings or significant structural timbers.

Question 5

How to identify dry rot decayed wood?

Answer 5

*Deep cuboidal cracking.
*Darkening of wood.
*Reduction in weight.
*Resinous smell gone.

Question 6

How to identify wet rot decayed wood?

Answer 6

• Longitudinal cracking along the grain.
• rotten timbers are darker in colour than surrounding.
• fruiting body = Mycellium, large vein hyphae. Olive green in colour.

Question 7

How would you remediate wet rot?

Answer 7

Cut back areas of wet rot and:
- splice in with new, or
- provide with resin repair
- Not as serious as dry rot!!

Question 8

What are the conditions at which dry rot occurs?

Answer 8

Moisture content: 20-35% (i.e. damp, not wet)

Temperature conditions: 0° to 26°C

(It is sensitive to heat, and will die on exposure to temperatures of 40°C for a very short period)

Question 9

What are the conditions at which wet rot occurs?

Answer 9

Timber moisture content, 45 to 60% (very damp)
Temperature -30°C to +40°C

Question 10

What are the typical causes of dry rot?

Answer 10

• warm stale air, i.e. lack of ventilation.
• leaking pipe.

Question 11

What are the typical causes of wet rot?

Answer 11

• leaking pipe.
• Penetrating damp.
  Anything which results in high moisture levels!

Question 12

How does insect infestation occur?

Answer 12

The female beetles lay eggs within the timber and feed on the nutrients contained within the wood, leaving frass (digestive waste) in the tunnels they form

Question 13

How can insects infestation be treated?

Answer 13

Treatment with low odour, insecticidal fluids can take form of spray or brush application or gel or injection treatments.

Fumigation may also be considered in certain buildings, though it is less effective, as it does not directly target the infestation.

Question 14

What are three common wood-boring beetles?

Answer 14

Common furniture beetle
Deathwatch beetle
Termite