Wet Rot, what it is and how it starts
How Wet Rot starts and develops
The range of Wet Rot fungal spores are omnipresent and these are widely dispersed by air currents. If a spore falls on untreated damp wood they will germinate by pushing out a hollow tube called a hypha which grows and branches to form a mass of hyphal threads called mycelium. Mycelium develops inside the timber and breaks down the wood for food.
Wet Rot is caused principally by Coniophora puteana, commonly known as cellar fungus. Poria vaillantii is another important wet rot fungus and a number of less common fungi also occur. While each fungus has its own unique features, the general appearance of wet rot is similar – as is the treatment. In window joinery, the fungus Phellinus contiguus is recognised as a major cause of decay; this fungus causes a white rot which is quite different to the usual appearance of wet rot (see table of differences).
Wet rot is typically confined to the area of dampness because the mycelium does not spread into walls, note that this is INTO and not onto walls. In rare instances mycelium can develop extensively and most wet rot fungi produce strands.
In the photograph opposite, the previous owner knew they had a damp wall, so they added a sheet of polyethene to the wall then clad it with timber. HUGE Mistake. The conditions behind the plastic became perfect for the rot to travel, eating along its way.