Venting a Bungalow
How do I vent a bungalow?
We own a late-1940s bungalow in Henry Ford's hometown. We'd like to insulate and drywall the 2x4 attic rafters, but I'm not sure how to provide air circulation through the areas where the rafters meet the roof valleys. Please help us with this head scratcher.
— D. Hubbell, Dearborn, MI
Tom Silva replies: Normally, I'd suggest that you drill holes in the lower ends of the valley rafters to allow some air to flow through the rafter bays. However, I'm not sure I'd feel too comfortable drilling into 2x4 rafters because they don't have a lot of strength to spare. So I think the best solution is to spray the underside of the roof with an open-cell polyurethane foam. It doesn't require ventilation channels because it also acts as a vapor barrier. This work has to be done by professional applicators, however.