While getting a home inspection done for a potential purchase, the inspector pointed out a light blue/grey mold throughout the attic, but he refused to extrapolate on the problem. Could this be an expensive problem to fix?
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 ’50s through the late ’70s. However, they are not required to specifically identify mold. See the Standards of Practice of the American Society of Home Inspectors for what is/isn’t included in a home inspection. That being said, what the inspector saw may, or may not, be mold. It more likely is just be the early stages of decay and delamination of the roof sheathing.
If this is the case, the solution is two-fold. 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 sheathing, something that could easily double the cost of your next roof replacement. If so, you may want to renegotiate the purchase price accordingly.