Dry Rot vs Wet Rot: How to Tell Them Apart

Timber decay is a serious problem in any property, but not all rot is the same. Dry rot and wet rot have different causes, appearances, and treatment requirements.

Wet Rot

Wet rot is the more common of the two and occurs in timber that has become consistently saturated with moisture. It's caused by various fungi and remains localised to the wet timber — it doesn't spread through masonry.

*Signs of wet rot:* - Timber feels soft and spongy when prodded - Dark brown or black discolouration - The timber looks wet, even in dry conditions - Cracking along the grain

*Treatment:* Remove the moisture source. Replace all structurally compromised timber. Apply preservative treatment to surrounding sound timber.

Dry Rot

Dry rot (Serpula lacrymans) is far more serious. Despite its name, it requires some moisture to start — but once established, it can spread through masonry to attack dry timber in other parts of the building.

*Signs of dry rot:* - White cotton-wool-like mycelium (early stage) - Orange/brown pancake-like fruiting bodies - Deep cuboidal cracking of the timber - Red-brown dust (spores) - Distinctive musty, mushroom smell

*Treatment:* Dry rot treatment is a major undertaking. All affected timber must be removed well beyond the visible growth. Surrounding masonry must be irrigated with fungicide. All new timber must be pre-treated.

The Bottom Line

If you suspect either form of timber rot, get a professional inspection. Delaying treatment always results in greater damage and higher costs.