Dry Rot (Serpula lacrymans) can cause decay of timber at a lower moisture content that the Wet Rot Fungi, e.g., conditions where there is poor ventilations, high humidity, and condensation, rather than extensive leaks. Blocked air bricks or a faulty damp proof course are also common causes, and has the ability to grow through damp masonry, brickwork and behind plaster. Therefore it can spread to a greater extent, and it’s eradication is more expensive than that of Wet Rot.
Timber decayed by Dry Rot (serpula lacrymans) is brown in colour and it splits into large cubes up to 50mm (2”) in size. These splits occur both along and across the grain. In addition there are usually masses of cotton wool-like, white to grey mycelium, often with yellow and lilac patches on the surface of the timber.
The presence of this mycelium is very characteristic and aids in identification. A characteristic musty odour can also be detected.
The mycelium contains strands which are up to 5mm (1/4”) in diameter and which become characteristically brittle when dry. They may spread from infested timber onto damp masonry and support further outbreaks in other parts of the building. When conditions are suitable, the fungus forms a fruiting body which is shaped like a flat plate, or bracket, which has a characteristic rusty red centre, with a white outer margin. The centre portion produces a lot of red spores, which often form a red dust over the surrounding area.
The correct identification of Fungal growth found during any inspection is an important part of any Remedial work.
Some growths may be relatively harmless whilst others may indicate the need for particular Remedial measures.
There are a number of Fungi which cause decay in building timbers. These are classified as either of the ‘Wet Rot’ type or as ‘Dry Rot’