Timber defects - rots and beatles

Question 1

What is wet rot?

Answer 1

Most common type is Ciniophora Puteana (known as cellar fungus).

Not as severe structurally as dry rot but can eventually cause failure.

Question 2

How would you identify Wet Rot?

Answer 2

Surface cracks that follow the line of the timber grain.

Thread-like strands of hyphae which are yellowish and become darker brown with age.

Fruiting body rarely found.

If fruiting body is present (usually outdoors) it is this olive brown plate irregular in shape with a knobbly texture.

Question 3

How would you treat Wet Rot?

Answer 3

Treatment:
1. Locate and eliminate source of moisture.
2. Promote rapid drying.
3. Determine extent of damage.
4. Remove timber 500mm beyond affected areas.
5. Treat infected timbers and install new pre-treated timber.

Question 4

What is dry rot?

Answer 4

Timber decaying fungus (Serpula Lacrymans) that digests softwood and hardwood timber, reducing its structural integrity.
Is not found in nature – only in internal timber constructions.

Question 5

How would you identify Dry Rot?

Answer 5

Identifiable by:
1. Timber can crumble.
2. Mushroom odour.
3. Dull brown colour.
4. Defined cuboidal cracking.
5. White, fluffy mycelium or can be pearly grey and white sheets (depends on humidity).
6. Pancake shaped / bracket shaped fruiting bodies with white edges and rusty red colouration (spores).

Question 6

How would you Treat Dry Rot?

Answer 6

Treated by:
1. Locate and eliminate source of moisture - survey structure and identify issues (defective plumbing, rainwater goods, damaged rendering, defective roof coverings etc).

2. Promote rapid drying - Heat the building and allow sufficient ventilation. Can use dehumidifiers but ventilation will need to be reduced to work. Remove floorboards adjacent to wet walls if necessary and increase / ensure sub floor ventilation - can even install heavy gauged polythene sheeting to oversite where floor is particularly wide.
3. Determine full extent of the outbreak - survey visually but also use screwdriver to detect softened wood. Where timber floor joists are suspected to be infected and embedded in walls plaster will need to be removed. Skirting boards and floor boards may also need to be removed.
4. Consult a structural engineer if structural timbers are suspected to be compromised.
5. Remove rotten wood - cut away 450mm beyond furthest extent of infected timber. Treat walls with fungicidal fluid. Apply sound timbers with preservative via repeat application to drilled holes, application of proprietary pasts of insertion of borate rods to ensure deep penetration. Then install new pre-treated timber.
6. Monitor.

Prognosis:
- Left untreated it will spread to other timbers through masonry and plaster and caused structural failure.

Question 7

How would you detect woodworm?

Answer 7

Bore dust (can collect in cobwebs under affected timber) and flight holes (1-2mm in diameter with more recent holes having sharp edges and lighter inner sides due to oxidisation not yet dulling the exposed timber).

Question 8

What is the common furniture beetle?

Answer 8

Type of woodworm responsible the most timber damage in the UK.

Emergence between May – September.

Found in softwoods, EU hardwood and plywood.

Found in timber with greater than 12% moisture content.

Question 9

What is the lifecycle of an insect?

Answer 9

Eggs laid by female in cracks / splits of timber or old flight holes.

Larvae hatch and then burrow into wood eating sap (when most damage done which isn’t visible).

Adult insect emerges from pupa skin and bores way out of timber forming exit holes.

This process can take a number of years to occur.