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Community and Q&A

Conditioned crawlspace, floor insulation

bradrh | Posted in Green Building Techniques on

I think every drawing & article I’ve read showed no insulation on the floor of a conditioned crawlspace. So far, I haven’t found any recent info on the heatloss into the ground or temperature of the ground below a conditioned crawlspace. There’s something in my old ASHRAE fundamentals for a basement floor, but it seems too high. It would seem that if there more than a little heat loss it should be insulated?

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  1. GBA Editor
    Martin Holladay | | #1

    What's your location or climate zone?

  2. bradrh | | #2

    zone 5, colorado.

  3. GBA Editor
    Martin Holladay | | #3

    In Zone 5, I don't think it's worth the cost to install rigid foam on the dirt floor of your crawl space. There is heat loss through the dirt, of course, but the heat loss isn't enough to justify the cost of insulating (and installing a rat slab to protect the foam).

    Every project is different, however, and ultimately, the answer depends on your project goals and your budget. If this is a Passivhaus, you may want to insulate the dirt floor. If you are already planning to install a rat slab, and you have access to some inexpensive recycled EPS, you may want to insulate the dirt floor.

    If you want to know how much energy you'll save, you need to perform some energy modeling.

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