What is Wet and Dry Rot?

Wet rot (Brown rot)

 Wet rot caused due to extremely wet conditions wood does not like being kept in wet, damp and dark areas if not treated. It is a natural product that will break down quite quickly if left to the elements so if you add a fungus it will be consumed until there is nothing left.

The most common form of wet rot is the cellar fungus (Coniophora puteana and C. marmorata) and will attack softwoods (pine) and oak (hardwoods).

The fungus causes the wood to darken with cracks along and across the grain as the wood rots. Where conditions cause drying on the surface, an apparently sound thin skin of timber often remains which may crack longitudinally as the decay progresses underneath.

Where the fungal attack is quite new it usually shows yellow discolouration on the surface. The Mycelium is only present where there is high humidity and rarely without brown strands. Cream to brownish in colour and often off white if completely left in the dark with no light source. It might also spread sketchily over damp plaster or brickwork. The strands are thin and usually brown or black although they are yellow when young. Fruit bodies are rare in buildings but if found they will be thin and lying flat on the wood. Cellar fungus has small irregular lumps and is olive green to olive brown with cream margins can be paler when young.

Dry rot (Brown Rot)

Dry rot spores are present in the atmosphere just like grass and tree pollen just waiting to settle on some poor soul. So if your home has a damp issue then these fungal spores will settle and start to increase rapidly. Given time the fungus will consume the timber it started from and will continue to give off a mouldy fusty smell.

When the airborne spores settle on damp timber, they will then send out thin grey spider web root strands that will spread across the surface of the wood. The dry rot fungus feeds by extracting the moisture from the wood this action will make the timber dry, crumbly and structurally inadequate.

These fungal root strands (hyphae) will quickly multiply in damp conditions and rapidly become matted, surrounding the wood. They then adopt the appearance of cotton wool turning grey (Mycelium) with lilac tinges and yellow patches. From this they produce (strands) which are white to grey and branch out sometimes as thick as a pencil, they are brittle when dry.

And in their final phase transforming into a mature, pancake shaped, rust coloured (fruit body) which emits millions of spores that drift off into the air and around you house if not detected yet.

Dry rot (Serpula Lacrymans) is often misdiagnosed because its appearance is constantly changing. It can sometimes look like other forms of rot, depending on what lifecycle stage it is at.

Brown and White Rot Fungus

Brown and White Rot

Because people are so familiar with the terms wet rot and dry rot, todays experts consider this to simple. Fungal decay to timber can now be more accurately categorized as brown and white. Brown rot includes all types of dry rot and its close relative cellar fungus. White rot includes most types of wet rot but not all.

The key difference is in their methods of attack that destroy different parts of the timber.

Brown rots work by removing cellulose from the wood, leaving behind a brown matrix of lignin (lignin is a chemical found in plant cell walls that makes them rigid and woody).

White rots also consume the lignin, leaving behind blanched looking decayed wood with an anaemic tinge. Despite this, brown is actually far more destructive than white.

Be Dri Customer Service

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