Ask the Expert Question-and-Answer Archive

by Ron Joseph

April, 2004

Mold

Q. There was some black mold on the inside of plywood sheeting, so I killed it with bleach. Before finishing the inside of the wall (with insulation and drywall). I would like to leave a mildicide on that surface to inhibit future mold. Mildicide is readily available as an additive to paint, but I don't want a paint that will be a vapor barrier. (Moisture movement out of the wall is desirable in both directions.) Is there a paint that will serve as a mildicide and allow for air flow?

A. By using a clear wood preservative, which is a thin low viscosity, low solids coating and not a paint, the mildicide could be added and applied to the plywood without concern of complete blockage of air.

The preservative will penetrate much more freely than a paint coating and because the plywood has rough open grain the passage of circulating air should be no problem.

Best wishes,

Tom Burke