Dry & Wet Rot


If you suspect that you have dry rot, we recommend that you contact specialists as soon as possible to inspect the problem as Dry rot can pose many risks to your building, as listed below:

• It does not need significant dampness to grow
(unlike wet rot)
• Grows rapidly through a building and is difficult to control
• Can spread behind plaster and through walls into neighbouring properties
• Compromises the structural integrity of a building
• If left untreated, it could lead to the collapse of the building



What is the difference between wet rot and dry rot?

Wet rot stays localised to the source of moisture and the timber is wet in appearance. It will also show signs of shallow cuboidal cracking on the timber surface. Dry rot can grow far from the source of the moisture with evidence of a white/grey coloured growth over the timber.

There are often signs of a white mushroom-like growth, known as a fruiting body, which expels reddish/brown spore dust into the surrounding area. The timber shows signs of larger cuboidal cracks more deep-seated than that of wet rot.



What is dry rot and how is it caused?

Dry rot (also known as fungal decay) is a wood destroying-fungus which feeds on moisture in timbers. Dry rot spores, which are always present in the atmosphere, land on timber, and in the correct environmental conditions will germinate and produce hyphae (fine strands of fungal growth). These hyphae strands join together to form a mass called Mycelium which can vary in colour from grey to pure white, and these strands grow into and across the damp wood. It can also grow into materials such as plaster, mortars, bricks etc.

When the growth is advanced a fruiting body (Sporophore) may develop. This fruiting body takes the form of a "fleshy pancake", the surface of which is orange/ochre coloured. A large number of spores generate from the centre of the fruiting body, under still conditions, and form the red "dust" often visible where there is a significant attack of dry rot.

Excessive moisture, from a flood, leak or defective guttering, for example. Rot can also occur when timbers are in contact with walls which are damp due to lack of ventilation or lack of an effective damp proof course, for instance. It is usually found in hidden unventilated voids where timbers are present.


How to identify wet rot


Wet rot causes distortion, discoloration, softness, cracking and the loss of strength to the timber. Sometimes there is a damp musty smell.

In some instances there may be visible fungal growth.

Dry rot is the most serious type of timber decay. It is a fungus that destroys the cellulose component of wood turning it brown, and eventually reducing timber to a dry and crumbly consistency.


How to identify dry rot


Dry rot has a distinct mushroom smell and white fungal growth often with yellow and lilac tinges.

The reddy brown fruiting body produces spores, which are deposited as a layer of brick red dust throughout the building.

Unlike wet rot there is extensive fungal growth and distinct cuboidal cracking of the timber.