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Insulating a Garage Ceiling: Worth the Investment?

  • Transcript

    LESLIE: Alright. Now we’ve got Mike in Iowa on the line who needs some help insulating a garage. Tell us about it.

    MIKE: Hi. I have a three-and-a-half or four – basically, a four-car garage underneath a house that’s a ranch. The trusses – the floor, it has trusses in it and it’s cold in there. And it gets cold here in Iowa and it stays, I don’t know, 35, 45 degrees during the winter, even in the coldest day.

    And it has batting insulation in it but it’s still cold. And our bedroom is above it, so I was thinking about putting some insulation in it, either in the – blowing some – drilling the holes and blowing it in or just doing it around the outside, the outer walls. Or am I just wasting my time trying to do any better?

    TOM: Alright. So, the garage ceiling – the walls between the garage and the house – should already be insulated. So what you’re asking is: can you add additional insulation to the exterior garage walls? Is that correct? Because that would be, theoretically, the only part of this garage that was not insulated.

    MIKE: Correct. Well, the outer walls are concrete.

    TOM: Oh, OK.

    MIKE: So it’s basically the ceiling I’m after. Would it be – because the cold air goes up the rooms above the garage.

    TOM: So, do you have any – the way the ceiling is configured, it’s drywall right now?

    MIKE: Correct.

    TOM: So there may not be any additional room above that to add additional insulation. You mentioned blown-in insulation. If that ceiling was built correctly, there’s already insulation there, so you may not be able to add more to that.

    This might be a situation where you need to improve the garage heat more than add to the ceiling insulation. Because short of building it downward so that you have more depth, I don’t see how you’re going to add additional insulation if it’s already insulated.

    MIKE: Well, there’s batting up there. I didn’t know if it would do any good to have them blow it in and pack it as tight as they can get it with that blown-in insulation.

    TOM: No, because insulation doesn’t work on being packed as tight as possible. Insulation works on the principle of trapped air. And so if you overpack the insulation, it becomes less effective, not more effective.

    MIKE: Right. Alright. Well, that tells me I would’ve wasted my money if I’d have – went and had somebody come out and blow it in.

    TOM: I know it might not be the answer you want but at least we didn’t have you spending money on something that wasn’t going to work, Mike. I hope that does help.

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