Spray Foam Insulation to Replace Fiberglass Batts

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    LESLIE: David in Alabama is on the line with an insulation question. How can we help you?

    DAVID: Several years ago, I discovered some termites. And it turns out the insulation of the house insulating the ducts was all soaking wet, so I took it all off and replaced it. And the termite people said, “Well, you’ve got batts under your house for insulation between the joists. And you need to take all that out of there because it tends to trap moisture and cause mold.” So they treated all of the wood and I yanked all the insulation out of there.

    TOM: And now you’re freezing.

    DAVID: Well, yeah. It was cold in the winter and the floor is noticeably colder and so I’m debating. I had two power ventilators put in under the house. I’m not sure how well they’re working but I was toying with the idea to put the insulation batts back at least under the living room, which seems to be cold. You know, the floor does.

    TOM: Alright. So here’s a couple of things, David. First of all, I never would have told you to remove your insulation. That’s kind of crazy advice that the pest-control operators gave you. If you have high moisture under the house – is this on soil? Crosses on the sand floor? Is the crawlspace on the sand floor or what’s the base?

    DAVID: Yes, it’s a crawlspace. Starts out about 5 feet.

    TOM: Is it on a dirt floor or is it on concrete slab?

    DAVID: It’s a dirt floor.

    TOM: And do you have a plastic vapor barrier on the dirt floor?

    DAVID: Oh, yes. I do now, yes. It was kind of in bad shape when I replaced it but I’ve got it all put down now on the floor, on the dirt.

    TOM: Yeah, you do now. Alright. So here’s all the steps that you need to take. First of all, to reduce the moisture, you start not in the crawlspace but outside the house. You check that your gutters are – that your gutters exist, the downspouts are extended 4 to 5 feet away from the house, not just dropping right at the corner of the foundation as most do. And you make sure that the soil slopes away from the exterior wall. Those things will reduce the amount of moisture that gets in there.

    Next, you’ve got a vapor barrier. And the vapor barrier should be all across the floor of the crawlspace and up the walls about a foot. You can seal the lip to the wall so that moisture doesn’t come out around that. You mentioned you had power ventilators. That’s good if you install those on a humidistat switch. So when the moisture comes up, those ventilators will kick on and draw it out.

    Now, as to the fiberglass insulation, you have another option and that is spray-foam insulation. You could opt to not use fiberglass, which does have to be vented and kept very dry. And you could switch to an Icynene closed-cell spray-foam insulation. Closed-cell spray-foam insulation is very moisture-resistant and has the added benefit of stopping drafts from getting through it, up into the house. And it’s sprayed on very thin and then it expands. It has about 100:1 expansion ratio and as it expands, it insulates and seals.

    We have a very old house, where my family lives up in New Jersey, and this house is 125-or-so years old. And we had it insulated with fiberglass until I converted to Icynene and really, I’ve never been happier. It’s been quite warm and comfortable. In fact, our air-conditioning bill last summer was about 50 percent of the cost it was the year before, when we did not have the Icynene. So I think that Icynene is a good product for this particular application because it is going to seal out that moisture and it’s going to leave the floor really super-warm. And it’s going to really step up your comfort.

    DAVID: Who makes that product?

    TOM: Icynene – I-C-Y-N-E-N-E. Go to Icynene.com. They have a dealer locator. You can have a pro come out to your house and scope it out.

    DAVID: OK. Thanks a lot.

    TOM: It’s good stuff, David. Good luck. Thanks so much for calling us at 888-MONEY-PIT.

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