Dry rot

Dry rot is a term commonly used to describe a particular kind of wood decay caused by certain species of fungi that digest parts of the wood which give the wood strength and stiffness. It is a misnomer because all wood decay is caused by the presence of moisture. The term is often confused with wet rot, but dry rot refers to wood decay caused by specific fungi, notably Serpula lacrymans, that thrive in conditions with a minimal moisture content.

Causes and Conditions

Dry rot occurs when wood becomes too damp, with a moisture content over 20%. The fungus Serpula lacrymans is primarily responsible for this type of decay. It can grow in conditions with less moisture than many other decay fungi require. The fungus spreads through the production of spores which are transported through the air. When these spores land on wood, in the right conditions, they germinate and grow, feeding on the wood and causing decay.

Identification

The presence of dry rot can be identified by a series of characteristic signs. Initially, the wood may show a silvery-grey discoloration with cracks running through it. As the condition progresses, the wood becomes brittle and can easily be crushed into powder. One of the most distinctive features of dry rot is the growth of the fungus itself, which can appear as a white or grey cotton-like sheet over the wood, often with patches of yellow or lilac. The fungus can also produce a fruiting body, which is a rust-red colored mass of spores, known as a sporophore.

Prevention and Treatment

Preventing dry rot involves controlling the moisture content in wood. This can be achieved through proper design and maintenance of buildings to avoid water ingress, and by ensuring that any wood used is properly treated and protected. Once dry rot has been identified, treatment typically involves removing the affected wood and replacing it with treated wood. In addition, it is necessary to eliminate the source of moisture to prevent further growth of the fungus. In some cases, chemical treatments may be applied to the remaining wood and surrounding areas to kill the fungus and protect against future infestation.

Impact

The impact of dry rot can be significant, particularly in buildings where it can weaken structural timbers, leading to costly repairs. It is not only a problem for the integrity of buildings but can also affect the value of property. Early detection and treatment are crucial to minimize damage and repair costs.

This construction related article is a stub. You can help WikiMD by expanding it.