Dry rot is type of brown rot decay caused by certain fungi that deteriorate timber in buildings and other wooden construction without an apparent source of moisture, which is also known as true dry rot.
The decayed wood takes on a dark or browner crumbly appearance, with cubical like cracking or checking, that becomes brittle and can eventually crush the wood into powder. An outbreak of certain types of a true dry rot fungus within a building is considered to be an extremely serious infestation that is hard to eradicate, and usually requires drastic remedies to correct. Eventually the decay can cause instability and collapse in structures.
Treating dry rot is a three step process. Step 1 is to locate and stop the source of the moisture which caused the problem in the first place. Until the source of the moisture is found nothing productive can be done. Step 2 is to replace any wood that is so damaged that it has become structurally weakened. Step 3 is to treat new and existing wood with borate to prevent future advance of the dry rot fungus and kill any fungus in the treated wood.