Wet rot normally effects outside timber but if the timber in a house has been wet at some point, for example due to a leaking roof or where there is inadequate ventilation then wet rot can occur, Leaking pipes or washing machines etc. have been known to cause wet rot.
Wet rot is easy to identify as the wood will be very damp, it could have cracked and will be dark and will shrink. Prod it with a sharp implement such as a screwdriver and the wood will probably crumble or will be very soft and pulpy.
Luckily wet rot is not normally that serious and can easily be treated, by repairing whatever is causing the wet rot in the first place, such as a leaking roof or faulty pipe, then leave the wood to dry which will kill the wet rot. When the timber is dry you can treat the affected wood and if the wood is really badly damaged either replace it or use a suitable wood repair system. The wood is best treated with a garden spray with a long hose and lance, use some suitable wet rot treatment and be sure to wear the correct face mask/ goggles and gloves.
When spraying any chemicals it is essential to wear the correct type of respirator
A garden sprayer like this can enable a large area to be covered in no time at all, care must be taken with some chemicals that contain solvents as they could attack the plastic
If the wet rot has been left for too long there might be no other option than to replace the rotten timber!