Roof Sheathing Rot and Decay: Inspector's Attic Find May Be Decay and Delamination Rather Than Mold

Roof Sheathing Rot and Decay: Inspector’s Attic Find May Be Decay and Delamination Rather Than Mold

Money Pit Team asks,

While getting a home inspection done for a potential purchase, the inspector pointed out a light blue-gray mold throughout the attic roof sheathing, but he refused to extrapolate on the problem. If we’ve indeed uncovered mold, could this be an expensive problem to fix?

Our Answer

Home inspectors should point out signs of excessive attic moisture and it is common for that moisture to cause decay, especially in homes constructed from the late 1950s through the late 1970s. However, they are not required to specifically identify mold.
That being said, what the home inspector saw may or may not be mold. It more likely may be the early stages of decay and delamination of the roof sheathing. If this is the case, the solution is twofold. First, deal with the cause, which is inadequate attic ventilation. To improve it, make sure your home has continuous ridge and soffit ventilation.
Many older homes simply don’t have adequate ventilation, and as such, moisture gets trapped in the attic where it condenses on roof sheathing causing decay. Secondly, you should ask your home inspector if the roof sheathing decay is serious enough to warrant replacement of the roof sheathing, something that could easily double the cost of your next roof replacement. If so, you may want to renegotiate the purchase price accordingly.