Here's a tip for deciding what kind of mold you have: wet rot/dry rot.
Ordinary mold leaves white furry deposits or black spots, but wet and dry rot, caused by dampness looks different and is much more serious.
Wet Rotted wood is spongy when damp, brown and crumbly when dry. To get rid of the rot, first get rid of the cause of the dampness. Then cut out the rotted piece and replace. Dry rot thrives in closed in spots. The infested wood is brown and brittle and the area smells musty. Call in a specialist and make sure he checks thoroughly, this problem spreads fast and widely.
Source: Mary Ellen's Clean House
By Randa from San Marcos TX