Dry Rot (Serpula Lacrymans)
Dry Rot affects timber that has become damp from a reasons similar to wet rots. When dry rot spores come into contact with something suitable for germination they develop into a cotton wool like appearance, which form white strands that extend along timber and masonry.
After some time the cotton wool like fibres darken and produce spores that are a reddish brown dust. This is now the beginning of a fruiting body that is producing spores that are released into the atmosphere.
Dry Rot consumes all the nutrients in timber and causes large cuboidal cracking to occur, and as the food is removed the strands travel though bricks, mortar and plaster in search of more food. When a new food is found the original fruiting body dies off and a new one is grown as the infection continues.
Dry Rot unlike Wet Rots can carry its own moisture as it travels through a property in search of more food. Dry Rot is capable of causing severe damage to structural timbers.
BUT IT CAN BE TREATED!
Dry Rot Treatments
In severe outbreaks opening up and disruption are necessary prior to being able to produce a full schedule of works and being able to give and estimate for the work. It is better to carry out a full investigation prior to starting treatments if possible, so that there are minimal surprises during the schedule of works.
All affected timbers will need to be removed and cut back to between 500mm and 1000mm depending on the situation to ensure that any signs of the infection are removed. This also applies to the plaster work, skirting boards etc.
The source of moisture should be removed and the area encouraged to dry out as quickly as possible. This is where the treatment of Wet Rot & Dry Rot changes as Dry Rot requires more extensive treatments.
Any masonry including subfloor solid below ground floor timbers requires treatment with a biocide. Thicker walls may require some drilling and irrigation. This is usually a "Cordon Sanitaire" drilled and irrigated around potential food sources within the vacinity as well as spraying wall surfaces and provide toxic boxes to eradicate the infection.
The damage to the timber causes wood to become weak and break up once the infection is well developed.
The colour of the strands depends on the two types of Wet Rot; White or Brown Rot.
- Brown Rots: darken timber and break it into small cuboidal cracks
- White Rots: make the colour of the timber lighter and the infection grows along the grain.
Wet Rot Treatment
Locate the source of dampness, remove it and replace the damaged timber ensuring that it is adequately protected against future problems if possible.
A source of natural ventilation is always preferable compared to forced drying as this may warp retained timbers.