Timber Rot - Types

Damp conditions can be the source of many different types of wood-decaying fungi. The principal agencies of decay are -
* Dry rot (Serpula lacrymans or merulius lacrymans), and
* Wet rot (Coniophora cerabella)

Dry rot - this is the most difficult to control as its root system can penetrate damp and porous plaster, brickwork and concrete. It can also remain dormant until damp conditions encourage its growth, even though the original source of dampness is removed.

Appearance - white fungal threads which attract dampness from the air or adjacent materials. The threads develop strands bearing spores or seeds which drift with air movements to settle and germinate on timber having a moisture content exceeding about 25%. Fruiting bodies of a grey or red flat profile may also identify dry rot.

Typical surface appearance of dry rot -

Wet rot - this is limited in its development and must have moisture continually present, e.g. a permanent leaking pipe or a faulty dpc. Growth pattern is similar to dry rot, but spores will not germinate in dry timber.

Appearance - fungal threads of black or dark brown colour. Fruiting bodies may be olive-green or dark brown and these are often the first sign of decay.

Typical surface appearance of wet rot -