Attic fans provide heat control in summer, moisture control in the winter and improve air circulation year-round. Whole house attic fans, which are mounted on the attic floor, are the most effective. They pull air from the home's interior, helping to cool the lower floors and reducing air conditioning costs.
Attics that have inadequate ventilation can lead to cosmetic and structural problems in a home. It begins when hot air is trapped in an attic with no way out. The air goes through the rafters and seeps out from under the shingles. After a while, the shingles start to curl up on the edges, allowing water to seep in.
The water seeping in can lead to moisture issues and wood rot, which attracts termites and carpenter ants. According to a study done at the University of Illinois, an attic floor fan is the best way to prevent the hot air build up and the resulting chain reaction of problems.
Another option is to use gable attic fans. Gables are the triangular areas on either side of a peaked roof. Usually, these have vents near the roof line. The fans are placed in back of these vents to help blow hot air out.
Additional vents are needed around the roof line, under the eaves. These are called soffit vents. They pull cooler outside air into the attic, forcing the hot air towards the fans and out of the attic.