Dry rot species of fungi cause brown rot decay, preferentially removing cellulose and hemicellulose from the timber leaving a brittle matrix of modified lignin. The term "dry rot" is somewhat misleading, as both species of fungi "Serpula lacrymans" and "Meruliporia incrassata" require an elevated moisture content to initiate an attack on timber (28–30%). Once established, the fungi can remain active in timber with a moisture content of more than 20%. At relative humidities below 86 percent, growth of "Serpula lacrymans" is inhibited, but it can stay dormant at relative humidities down to 76 percent. These relative humidities correspond to equilibrium moisture contents
Serpula himantioides appear as distinctive fruiting bodies on the exterior of the host. "S. himantioides" prefers the moist wood of coniferous hosts such as fir, larch, spruce, and pine. It is the causal agent of butt rot disease, the symptoms of which include rotting the heartwood at base of tree, as well as damage to the tap root and cores of lateral roots, but standing trees show no signs of infection. It also a common cause of timber rotting in buildings, which has made this pathogen difficult to differentiate from "S. lacrymans" because of their similarities. This disease often goes unnoticed initially