Q. What are the advantages of applying spray foam directly to the underside of the roof? Doesn’t my attic need ventilation?
A. Attics were traditionally vented to remove excess moisture and reduce heat build-up. New research suggests that venting attics may actually make the situation worse and greatly add to our energy costs. Because warm air rises, vented attics create a stack or “chimney” effect that continuously pulls moist air from crawl spaces and basements into the attic, contributing to a greater moisture load. Further, during the night the colder air rapidly cools the roof which can cause condensation to form. And to make matters worse, radiant heat during the day heats up the roof and easily passes into the attic generating excessive temperatures which then pass into the living space below.
We can solve all of these moisture and heat build-up problems by applying spray foam directly to the underside of the roof deck and sealing off the attic from the outside environment. By sealing off the top of the house we eliminate the “chimney” effect that would otherwise occur. We further prevent the hot moist air by day and the cold air at night from continuously venting in and out of the attic – stopping moist air from entering the attic all together is the best way to control moisture related problems. A conditioned attic also greatly reduces our cooling loads during the summer and heating loads during the winter. Additionally, since spray foam is an excellent thermal barrier, ice damming during the winter is prevented since heat is not easily transferred to the roof causing snow to melt.
Of significant importance, an unvented attic reduces the stress load on HVAC systems and ductwork which may be located inside an attic. A vented attic exposes heated or airconditioned air to extreme temperatures, dramatically reducing the efficiency.