Proper attic ventilation is one of the most important, yet least understood systems in a house. On a regular basis, we inspect homes with venting problems that range from mild (not yet causing a problem)… all the way to severe (deterioration of the rafters and roof decking).
Attic ventilation is almost always passive in nature, as it relies on convective air flow, where cooler air is drawn into soffit vents along the eaves and rises through the attic and passes out the roof vents on top. Both soffit and roof vents can easily become blocked, and should be inspected on a regular basis.
The recommended minimum attic ventilation rate is one square foot of roof ventilation (one typical roof vent provides approximately one square foot of ventilation) for every 150-200 square feet of attic space… remember, as far as attic venting is concerned more is almost always better!
Improper attic ventilation can lead to higher energy consumption, as an air-conditioner will have to work harder to maintain a constant indoor temperature on the upper floors.
Improper attic ventilation and the resulting higher temperatures in the attic space can lead to accelerated shingle deterioration. We have personally measured temperatures as high as 155? F in a poorly vented attic!
In cold weather, proper ventilation helps prevent moisture from condensing on the insulation, structural members, shingles, or on the roof. This will minimize chances for mold growth and will help prolong the life of these components.
Proper ventilation, combined with proper attic insulation, are the keys to reducing the chances of ice-dams forming along the lower roof edge in the winter time. For more information about residential foam insulation and attic insulation contact the Spray Foam Pros today.