Dry rot - Serpula lacrymans

Habitat:

Mostly softwoods.
This is a major building decay fungus which often causes extensive damage. It is a brown rot which typically occurs on wood embedded in, or in contact with, wet brickwork. It is sensitive to high temperatures (over 25 degrees C) and drying, and is therefore rarely found on exposed timbers or situations where fluctuating conditions are likely, such as well-ventilated sub-floors or roofing timbers. It is able to grow through bricks and mortar, though it cannot feed on these. Strands can move moisture from damp areas, allowing the spread of the fungus to dry wood in unventilated conditions. The appearance of the fruit-body may be the first indication of an outbreak.

Damage characteristics:

Decayed wood is a dull brown colour, typically with deep cracks along and across the grain. The wood is light in weight and crumbles between the fingers. There is no skin of sound wood.

Fungal characteristics:

Mycelium Silky white sheets or cotton-wool-like white cushions with patches of lemon yellow or lilac tinges where it is exposed to light. In less humid conditions it forms a thin, felted grey skin. During periods of active growth the advancing hyphal edge forms a silky fringe.

Strands White to grey, branching, sometimes as thick as a pencil. Brittle when dry.

Fruit-body Usually on wood/wall joint, rare on the outside of a building. Tough, fleshy, pancake or bracket-shaped. The centre is yellow-ochre when young, darkening to rusty red when mature owing to spore production, covered with shallow pores or folds. The margin is white or grey.

Spores Profuse and may settle as a fine layer of reddish-brown dust on horizontal surfaces.