A dry rot is a form of wood decay found in houses, resulting in loss of strength of timbers. The causal agents are the basidiomycete fungi Merulius lacrymans (in Britain) and Poria incrassata (in North America). Preventative measures include ensuring that conditions for ideal growth of the fungus are avoided, i.e., relative humidity is kept low, no free moisture is allowed, and wood surfaces are covered. Treatment for the disease includes painting the wood surface with creosote and using fungicides to kill the fungus.