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What’s the Best Type of Insulation for Exterior Walls?

  • Transcript

    LESLIE: Tuan in Nebraska is on the line with some help on an insulation project. What can we do for you?

    TUAN: My home was built in 1935 and I’d like to insulate the exterior walls. What would be the best way to do that? Either foam or blowing in insulation?

    TOM: So you are confident that there’s no insulation in those exterior walls right now, Tuan?

    TUAN: There’s none in there. I’m very confident.

    TOM: So, because we don’t want to have you open up all the walls, probably the best thing to do is to do blown-in insulation. That can be blown in from the interior or from the exterior, depending on how – where you would like to patch it. To blow in insulation, they drill holes that are about an inch to an inch-and-a-half in diameter and then usually, you use cellulose that’s blown in under a slight pressure.

    And it’s important to work with a company that’s very experienced with the product, because they have ways to make sure it gets to all the spaces it’s supposed to get to and account for settling of it.

    For example, one of the ways to do that is after the insulation is installed, they’ll use an infrared camera to basically scan all your walls and look for cold spots that would indicate a place where insulation did not get to. So I think blown-in is the way to go with that thermal verification.

    TUAN: OK. So thermal – ask for a thermal verification?

    TOM: Yeah. And it really shouldn’t be anything extra. It should just be part of their tools because otherwise, how do they know they’re getting the insulation everywhere it should be? I would also tell you to make sure you double-check the amount of insulation you have in your attic because as uncomfortable you think you might be because of those walls, they are actually responsible for a very small part of the heat loss compared to the attics. Attics are responsible for the bulk of heat loss in homes.  You want to make sure that the insulation over head in your part of the country is 15 to 20 inches of fiberglass insulation.

    TUAN: Thank you very much.

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