Dry & Wet Rot

Dry rot and wet rot is found in buildings of any age and if signs of it are present they should be identified and remedial action taken without delay.

Fungal decay will occur in timber which has been wet for some time and the result of it being attacke by wood-destroying fungi.

The most serious of these is dry rot, caused by Serpula lacrymans. It can spread onto and destroy much of the timber. Wet rot occurs more frequently, but is less serious; decay is typically confined to the area where timber has become and remains wet.

For fungal decay to arisethe wood must have become wet, usually timbers will have excess of 20 per cent moisture content. Once a problem is identified locating the source of dampness and eliminating the ingress of moisture and encourgaing drying is the first steps in remediation.

Both dry rot and wet rot start in similar ways with mature fruiting bodies of wood-destroying fungi developing to produce millions of microscopic spores and these are widely dispersed by air currents. If they fall on untreated damp wood they will germinate.

Dry Rot

Dry Rot is a wood destroying fungus (Serpula lacrymans) found throughout the world and although it can affect forest timbers it is commonly known for its ability to damage buildings and ships. Dry rot can cause widespread and sever structural damage and treating it quickly is imperative.

Serpula lacrymans will develop on the surface of infected timber and in still, humid conditions it prodcues a mass of cotton wool-like growth- often with small water droplets on the mycelium.

Identifying whether timber decay has been caused by dry rot rather than another wood destroying fungus is important as dry rot has the ability to travel through building material other than timber which means that it can spread quickly throughout an entire building. When treating for dry rot often these other non-timber materials need to be treated as well as the wood itself.

Typical signs of dry-rot include:

Wood shrinks, darkens and cracks in a ‘cuboidal’ manner

A silky grey to mushroom coloured skin frequently tinged with patches of lilac and yellow often develops under less humid conditions. This ‘skin’ can be peeled like a mushroom.

White, fluffy ‘cottonwool’ mycelium develops under humid conditions. ‘Teardrops’ may develop on the growth.

Strands develop in the mycelium; these are brittle and when dry and crack when bent.

Fruiting bodies are a soft, fleshy pancake or bracket with an orange-ochre surface. The surface has wide pores.

Rust red coloured spore dust frequently seen around fruiting bodies.

Active decay produces a musty, damp odour.

Dry rot control and Treatment

Dry rot only affects timber that is damp so removal of the source of moisture is the core part of treating dry-rot. The damp may be caused by a number of factors including condensation, rising damp, penetrating damp or water leaks and once the source of damp is eliminated the timber will be allowed to be dried out ahead of treatment.

As it is not always possible to guarantee that the damp issue will not re-occur it is important that timbers are treated with a fungicide to avoid a re-infestation of dry-rot. Where required this treatment will extend to other materials too.

For advice on the identification and treatment of dry rot contact SHD Property Care today.

Wet Rot

Although not as serious as dry rot damage can still be extensive to a property – this is especially the case where it occurs in damp basements. As with Dry Rot the cause of the damp has to be identified and remedied and for issues in floor timbers ensuring adequate under floor ventilation is key.

This type of rot is caused principally by Coniophora puteana or Poria vaillantii but there are a number of less common fungi which can occur. While each fungus has its own unique features, the general appearance of wet rot is similar – as is the treatment. Wet rot is typically confined to the area of dampness because the mycelium does not spread into walls.

Identification and Treatment

It is vital that the type and cause of the fungal decay are correctly identified before any corrective action is taken. A detailed diagnostic inspection should be carried out and a report produced that details both the cause of the decay and the proposed remedial action.

Identification of wet rot can be through one or more of the following symptoms:

A damp or musty smell

Timber that is cracked or softened and may be discoloured or distorted

Evidence of fungal growth

Treatment of the wet rot relies on a combination of eliminating the source of the damp and then replacing the affected timbers.

Ayrshire’s timber and wood treatments specialists - for dry rot, wet rot, woodworm and rising damp advice call SHD Property Care on 01294 275 069 or send us an email.