Wet rot is a general term used to describe the majority of fungal species responsible for timber decay. This rot attacks wood in damp conditions and can cause significant damage over time, if left unidentified and untreated.

There are a number of signs to look for, which could indicate the presence of wet rot: 
Distortion, discolouration, softness, cracking and the loss of strength to the timber
Smell – there may be a damp musty smell.
Visible fungal growth – this may sometimes occur.