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Community and Q&A

Air sealing near soffit question

DrJimesTooperMD | Posted in General Questions on

Hi there everyone, first time poster here. I am in the process of air sealing my attic, in addition to installing baffles so that I can add insulation on top of the existing fiberglass batts that are in between the joists in my attic.

My question is, where exactly should I air seal near the soffit vents and baffles? I have attached a couple of pictures showing what I currently have in my attic. I have pulled away all of the existing fiberglass batts for now. In the pictures I have drawn some red arrows and lines indicating where I was thinking I should air seal with Great Stuff foam, but wanted to confirm with you folks here that this would be a worthwhile exercise. I am already sealing top plates and any other penetrations that I can see on the attic floor, but wasn’t sure what I should seal next to the soffit vent.

Should I also seal around the edges of the baffles themselves?

Thank you!

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  1. GBA Editor
    Martin Holladay | | #1

    Dr. Jim,
    In general, it's a good idea to air seal the areas that you have indicated. You will also probably need to install wind-washing dams under each of your ventilation baffles, and these wind-washing dams also need to be installed in an airtight manner.

    More information here: Site-Built Ventilation Baffles for Roofs.

  2. DrJimesTooperMD | | #2

    Thank you for the quick reply Mr. Hollday. This is the first I've heard about wind washing dams. I'm assuming the flap coming down from the Accuvent baffle does not qualify as sufficient to block wind-washing?

  3. GBA Editor
    Martin Holladay | | #3

    Dr. Jim,
    The flap that comes down from the Accuvent baffle is indeed a wind-washing dam. Install it in an airtight manner, and you are good to go.

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