Timber decay has usually been caused by dry rot or another wood-destroying fungus such as one of the wet rots. Affected timbers should be removed and replaced with pre-treated timber, whilst any remaining timbers at risk of being affected by the rot should be treated with an effective fungicide. Where rot has passed through the masonry, it should be isolated using physical containment and/or masonry sterilisation.
Timber can become damp for a number of reasons although among the most common causes are leaking washing machines, shower trays, baths or condensation. The dampness can also come from outside the building, for example, leaking roofs, rising dampness or dampness penetrating through walls.
Woodworm holes found in timber are caused by the larvae of beetles that feed on the timber. Larger holes on the surface of the timber are formed when the adult beetle emerges from the timber to mate. There are a number of species of woodworm, and the precise method of treatment will depend on which species is attacking the timber.