Wise to block gable vents in lieu of soffit vents?
SwissCarpenter
| Posted in Energy, Heating & Insulation on
I’ve got a 1900 square foot 50’s era ranch house and I’m getting ready to insulate the attic. The house currently has fairly large gable vents (triangles roughly 3x3x5) at the apex of the gable. When the house was reroofed by the prior owner, a number of roof vents were installed on the rear/west side of the house. I’m going to install soffit vents and baffles prior to blowing in cellulose. I’ve come across a few people that advocate sealing up the gable vents since there’s a chance that they’ll disrupt air movement from the soffit vents to the roof vents. It kind of makes sense since the air will take the path of least resistance as it rises. Could someone in the biz give me some concrete advice on this one?
Replies
Take a look at this thread dealing with the same question:
http://forums.finehomebuilding.com/breaktime/general-discussion/it-necessary-close-gable-vents-when-roof-ridge-vent-added
Generally from what you describe, I think there is a good chance that it would be okay to leave your gable vents in.
If you're going to
install new insulation, make sure you air-seal the entire attic floor very carefully before the insulation goes in. A good air-sealing job will dramatically reduce the amount of humidity from the interior that makes it into the attic, and will help make the venting details a lot less important. After you do the insulation work, check the attic periodically, and if there are signs of trouble you can decide how to rectify.
I didn't read the above mentioned thread, but I did see a recent episode of This Old House where this was mentioned. It might be available on line to view.
What Tommy said was, in a nutshell, If you have ridge venting and soffits the gable vents would be a problem. He claimed that the Ridge Vent would draw air using the path of least resistance, which would be the Gable Vents as they are the closest.
That would severely decrease the draw through the attic baffles from the soffits, which would move more air along a more widely distributed area.