Spread by airborne spores which settle on damp wood in badly ventilated rooms. The mycelia of the fungus Serpula lacrymans can grow through bricks, mortar and wood. Infected wood turns dull brown and breaks up in cube shapes. The rot may travel over 2 metres a year, causing major structural damage to buildings. It tends to occur where there has been flooding, rising damp or leaking plumbing.
In the UK, it has been estimated that 25% of houses have either dry rot or wet rot.