Dry Rot
Dry rot is a form of fungal decay that is a misnomer as it does require moisture. The fungi feed on the cellulose in the wood fibers leaving the darker lignin (material for making cells) behind. The deterioration is visible as a dry, crumbled area that is extremely dry and has removed the strength of the wood in that location. For dry rot to set in, the wood needs between 20% or greater sustained moisture. There are four stages to help determine a dry rot outbreak: Mycelium growth as a white or gray cottony substance, a fruiting body (Sporophore) of a rusty appearing stain on the wood, a dry shrunken appearance with cracks across the grain, and often a rotten smell to the wood. As dry rot fungi can spread in search of new source of moisture, the moisture content of the wood need only be 20% to 30%. One of the differences between wet rot and dry rot is wet rot generally is in very wet areas, over 50% moisture content, and the fungi don’t travel beyond the wet wood. Dry rot wood seeks out nearby wood, even if not very damp, and so needs to be replaced and moisture levels controlled.