Wet and dry rot
This type of rot is caused principally by Coniophora puteana. Poria vaillantii is another important wet rot fungus and a number of less common fungi also 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
Fungal decay always arises because the wood has become wet, usually timbers will be in excess of 20 per cent moisture content.
If wood remains wet for long periods of time, there is a high chance of wood rot fungi developing, causing softening of the surface of the timber to an increasing depth as the wood becomes more saturated the longer it is left.
However, the danger with wet rot is that if it is left untreated, the timber starts to lose its integrity and, in some situations, becomes unsafe. Wet rot is particularly common around wooden window and door frames.
Very wet timbers will also be at risk of infestation by wood boring weevils and woodworm.
Treating wet rot
It is a common fact that Wet rots are able to develop when timber is saturated by moisture from a source such as leaking plumbing or a leaking roof roofing, or by absorbing moisture from structural masonry materials, such as damp walls that the wood is in contact with. Finding the source of dampness and eliminating the ingress of moisture and promoting drying is always necessary. It is important to remedy the cause of damp and isolate the timbers from the damp source, before treating the timber with a fungicidal rot treatment.
When treating wood rot, it is important to also use the treatment on timbers that do not have the wood rot present to a certain extent – this is to prevent future outbreaks on untreated timbers. The treatment usually includes cutting out of severely affected timbers and replacement with new treated wood. If woodworm is present the treatment will involve a dual-purpose rot and woodworm treatment
Dry rot is only caused by Serpula lacrymans (DRY ROT) and is the most serious form of fungal decay in a building. It can spread onto and destroy much of the timber
Serpula lacrymans develops extensively on the surface of infected timber and in still, humid conditions produce a mass of cotton wool-like growth. Water droplets are often produced on the surface of the mycelium.
Mycelium spreads over the timber surface by the continued growth and branching of the delicate hyphal threads growing with time. Specialised strands develop within the mycelium and these supply water and nutrients to the growing fruiting bodies. The strands assume their real significance when the fungus spreads from infected timber onto the surface of adjacent stone or brick walls. The tiny hyphal threads penetrate the mortar joints and plaster layers and large areas of damp wall can then become infected.
If left untreated, Dry rot causes considerable damage not only to timber but masonry also.
Treating dry rot
Treatment will include the removal of infected timber and replacement with new treated timber. A surface application of masonry biocide. Isolation of any timbers in contact with affected walls. A dry rot fluid applied to all timbers required, and identified by a PCA qualified surveyor. Dry rot works are extensive. So it is very important that the type and cause of the fungal decay are correctly identified before any corrective action can be considered. It is for these reasons that it is important that a detailed diagnostic inspection is carried out by a competent specialist. This inspection will be followed by the submission of a detailed report that highlights both the cause of the decay and the proposed remedial action.