Wet Rot

Latin name: Coniophora puteana and Coniophora marmorata

There are many fungal species causing wet rot; the same remedial measures are required for all of them. They cause a darkening of the timber (brown rot) or bleaching (white rot). Some types are only rarely seen in buildings. Soft Rot can be regarded as a superficial form of wet rot. It is more usually found in timber in ground contact.

Habitat

Softwoods and hardwoods.

General Information

Commonest cause of decay in woodwork which has been soaked by water leakage.

Damage Characteristics

Wood darkens with cracks along and across grain, but usually less deep than those caused by Serpula lacrymans. Where conditions cause drying of wood surface, and apparently sound skin of timber often remains which may crack longitudinally as decay progresses beneath. Freshly colonised wood usually shows yellow discolouration.

Dry Rot

Latin name: Serpula lacrymans

General Information

Major building decay fungus often causing extensive damage. Brown rot which typically occurs on wood embedded in, or in contact with, wet brickwork. Sensitive to high temperatures (over 25C) and drying, and therefore rarely found on exposed timbers or in situations where fluctuating conditions are likely (e.g. well ventilated sub floors and roofing timbers). Able to grow through masonry, though cannot feed on it. Strands can transport moisture from damp areas, allowing spread of fungus to dry wood in unventilated conditions. Appearance of fruit-body may be first indication of outbreak.

Damage Characteristics

Decayed wood has dull brown colour typically with deep cracks along and across grain. Light in weight and crumbles between fingers. No skin of sound wood.

Fungal Characteristics

Mycellum Silky white sheets or cotton wool-like white cushions with patches of lemon yellow or lilac tinges where exposed to light. In less humid conditions, forms thin, felted grey skin. During active growth, advancing hyphal edge forms silky fringe. Tears in direction of growth. Strands White to grey, branching, sometimes as thick as a pencil. Brittle when dry. Fruit-body Usually at wood-wall joints; rare on exteriors of buildings. Tough, fleshy, pancake or bracket shaped. Centre is yellow ochre when young, darkening to rusty red when mature owing to spore production. Covered with shallow pores or fold edges white or grey. Spores profuse and may settle as fine layer of reddish brown dust on horizontal surfaces.