Attic insulation/ventilation problem
I discovered mold in the rear bedroom and called a mold spe******t. He said the mold is caused by the attic not being ventilated efficiently thus causing condensation in the walls. He pointed out that there is only one soffit vent since the other one is a fake; a ridge vent, and two eave windows that are closed. My house has a gambrel roof on the front and a tradional roof on the back. The attic floor has batt insulation and blown-in insulation. His suggestion is to install spray-on foam insulation in between the rafters and thus, preventing the heat transfer from the house to the attic since the attic will be at the same temperature as the house. The mold spe******t's suggestion sounds logical, but please let me know if it is.
Re: Attic insulation/ventilation problem
Mold is usually a ventilation problem, but can also be an indicator of thermal bypasses. Is the mold consistent or more localized? If it is in one area but not others, check for a bypass. Make sure if you have any exhaust fans that they are vented out a dedicated, dampered roof vent, and the exhaust pipe for the vent is wrapped with insulation. If ventilation is needed, add a roof or gable vent if possible. Your ridge vent is equal to 107 square inches net free vent area per 10 feet of vent, but should have low venting also to work effectively. The attic, if properly insulated and vented, should be as close to the outside temperature as possible. Mold can grow on sprayed foam also, unless it has a mold inhibitor which would only mask the underlying problem.
Originally Posted by maxwell