White-rot and brown-rot fungi most often produce a whitish, cottony growth on the surface of wood. They grow only on moist wood. White-rot and brown-rot can be present in wood when it is brought into the house, or they can grow from the spores that are always present in the air and soil. Wood attacked by these fungi should not be used in construction. Wood decayed by brown-rot fungi is brittle and darkened in color. As decay proceeds, the wood shrinks, twists, and cracks across the grain. Ultimately, wood becomes dry and powdery with decay. Brown-rot is the most common type of decay found in homes.

Wood decayed by white-rot fungi becomes fibrous and spongy and is bleached in color. Sometimes it developes thin, dark lines around decayed areas. The wood does not shrink until decay is advanced.

These fungi can be controlled by eliminating the source of moisture that allows them to grow, for example by improving drainage and ventilation under a house, repairing water leaks, or preventing water seepage. When the wood dries, the fungi die or become dormant. Spraying wood with chemicals does not control decay. If the moisture source cannot be eliminated, all the decayed wood should be replaced with pressure-treated wood.