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Community and Q&A

Should I block the gable vents now that the house has new ridge vents?

jrphml | Posted in General Questions on

I just had my roof reshingled for the first time. The contractor installed ridge vents. I already have soffit and gable vents.
Should I block the air flow coming through the gable vents?

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  1. charlie_sullivan | | #1

    I'd be inclined to keep the gable vents, especially if you are in snow country. I'm a little skeptical about how well ridge vents work when there's a lot of snow on the roof.

  2. GBA Editor
    Martin Holladay | | #2

    1. The traditional advice would be to block the gable vents. Research shows that the most effective combination of attic vents is soffit vents + ridge vents, without any gable vents.

    2. In reality, however, either way is fine -- because attic venting is less important than most people think. For more information on this issue, see All About Attic Venting.

    3. Although Charlie is right that ridge vents are less effective if they are covered with a deep layer of snow, I wouldn't worry about that issue for the following four reasons: (a) Wind usually clears snow from ridges fairly quickly; (b) Fluffy snow isn't an air barrier in any case, so the ridge vent will still work even if there is snow above it; (c) Ice tends to build up in roof valleys but almost never on ridges; and (d) Mold and rot don't occur in winter because temperatures in winter are too low for mold or rot. Mold and rot occur during spring, summer, and fall, after the snow on your roof has melted.

  3. charlie_sullivan | | #3

    Although Martin has rebutted my argument quite thoroughly and effectively with his four points, I'll take issue with one of those rebuttals: if the concern is avoiding ice dams, rather than avoiding mold and rot, that is an issue at the times of year when there is a lot of snow. Of course, the right solution to ice dam problems is to seal any air leaks into the attic, but in my experience, things don't always get done right.

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