Dry rot is more serious than wet rot because it can spread through mortar, brickwork, and even concrete in search of damp timber. Left untreated, it can cause significant structural damage, weakening joists, floorboards, and rafters, and potentially leading to the collapse of roofs or floors. The spores for dry rot are ubiquitous in the environment and only become problematic when they find damp timber to feed on. Once they have enough moisture, they germinate and form a fluffy, cotton-wool-like fungus that eventually grows into a fruiting body, releasing more spores and perpetuating the cycle.