Attic ventilation
In the article on attic sealing on the Building Science Corporation Site and in a recent Fine homebuilding article, they talk about the pressure that having a ridge vent only (in the attic) can create thus sucking conidtioned air from the house out of the home.
In a conversation with someone I am contracting with to do insulation, the person indicated that if an attic is air sealed than there shouldn’t really be any place where conditioned air can be sucked from the building. This house is a historic masonary house in the St. Louis area. Ceiling is plaster with lathing. When we reroofed I had a ridge vent put in but no soffit vents. At the time I couldn’t find a person to do it.
Would a ridge vent only attic in this type of situation still experience pressure to direct heat out of an attic?
Thanks.
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Replies
Julie,
There are two types of attics: vented unconditioned attics and unvented conditioned attics.
If your attic has a ridge vent, I assume it is a vented unconditioned attic. It is certainly possible for a ridge vent to contribute to air leakage from your home; the solution is to perform air sealing work at the ceiling plane. This is usually done by lifting the existing insulation on your attic floor, locating the air leaks, and sealing them with spray foam, caulk, or sheets of rigid material. It's also important to install weatherstripping on your attic access hatch.
If you have already had this work performed in your attic, don't worry. Your attic is fine.
The most important variable in this equation is not the ridge vent -- it's the leaky ceiling. If you seal the ceiling leaks, everthing will be OK.