Fungus types in timber
There are many types of fungus, but most of them occur to the tree while still growing and will be selected out when felled so don’t concern us here.
The first type of fungus that concerns us belong to the group called “ Ascomycota”. This fungus mainly attacks softwood. The sign that the timber has been effected is that the timber will have a grey/blue colour to it, the fungus only attacks the the inside of the cell structure, but leaves the cell structure whole, so the structural properties of the timber will not be affected in any way, only the appearance is affected. The way to avoid the timber becoming affected is when the tree is felled, it should be milled and stacked to dry as soon as possible.
The second type of fungus that concerns us is “Serpula Lacrimans” (dry rot)
In it’s natural habitat in forests or woodlands it is an edible fungi. It doesn't affect healthy trees, so it is good in managing woodlands and clearing out the old and diseased trees and helping in the food chain, processing the wood in trees and making them edible for beetles and larvae. But in our case a very destructive fungi It is estimated that in Britain roughly 150 million pounds of damage yearly is caused by it.
Ideal temperature for growth 18-22 Celsius. The same temperature that we are happy with. So it is well suited to our environment.
When the rot has set it roots (mycel) they can grow through brick work. They grow through the lime mortar between the bricks.
They can grow along walls on the back side of wall paper, on the under side of carpet or vinyl, so it doesn't necessarily need timber to travel along to aid its progress through a structure. In built up areas it can pass from house to house through connected roofs.
Serpula, can also become dormant if the source of moisture dries up. It can remain in its dormant stage between 3 to 7 years. If the old source or moisture is not sealed or a new one is found then it can reactivate itself. So sometimes it is not good enough to just seal up the source of the original problem. Old buildings have often more than one source. Sometimes the body of the fungi can be found in one part of the house, but the source somewhere totally different.
Serpula needs to be treated aggressively, the area where the roots (mycel), body of the fungi and the source of moisture need to be opened up. The roots needed to be traced back and when the last has been found an area of 1.50 meter past the last root need to be taken out. This often means that a room has to be gutted, right back to the brick work. All timber that is removed needs to be burnt. If Serpula has grown on brick work the brick work needs to be flamed to destroy any spores. Once it has been flamed the brick work needs to be treated with suitable treatment. When room isrebuilt all new timbers that are installed will also have to be treated . All timbers should also have suitable damp proof course under them and no ground contact. All joining timbers should be connected with butt joints and metal fasteners (no timber joints) this will slow fungi growth if it should grow again.