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Insulating Floors Over a Crawl Space

By: Danny Lipford

Insulating the floor over a crawl space can reduce heating costs, particularly in colder climates, but it doesn’t provide as big a return on investment as insulating an attic or sealing cracks and gaps around your home.

When insulating the floor above a crawl space:

  • Turn the paper facing on the insulation up toward the heated living space to prevent condensation from forming.
  • Use insulation support wires to hold the insulation in place.
  • Cover the ground in the crawl space with 6-mil thick plastic to reduce moisture problems under your home.

Watch this video to find out more.

Further Information

Video Transcript

Danny Lipford: Frank asks, “Do I really need to insulate my crawl space?”

While insulating your crawl space is not absolutely necessary, it will help a lot to minimize any of the moisture or temperature intrusions into your home. But to tell you the truth, it’ll take you a long time to get your money back on the money that you spend on insulating that crawl space.

Far better to spend that money in the attic making sure it’s insulated well, and sealing up the envelope of your home. But if you decide to put insulation in your crawl space, make sure you turn the paper toward the living space, so that you don’t create any type of moisture trap.

Now, moisture is a big problem in crawl spaces, so it is strongly recommended to put a moisture barrier right on the ground. You can use a 6-mil plastic, clear or black, then you can weight down the perimeter of it with some small bricks, gravel, sand, or just a little bit of dirt to keep it from blowing away.

This will prevent the ground moisture from migrating up into your home, which ends up costing you some money.


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9 Comments on “Insulating Floors Over a Crawl Space”

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  • Official Comment:

    Thomas Boni Says:
    January 26th, 2019 at 4:24 pm

    Hi, Jane!
    We recommend submitting questions involving unique situations like yours to the Today’s Homeowner Radio Show.
    Please use this form to contact Danny Lipford, America’s Home Expert, directly:
    Take care!

  • Jane Says:
    January 26th, 2019 at 6:44 am

    We had a sunroom added many years ago and the contractor put insulation under the deck. Now some of the insulation is falling or looks like some animal has gotten into it and tearing it apart in places. Would it be best to cover it, or leave it, any suggestions?

  • Official Comment:

    Thomas Boni Says:
    January 15th, 2019 at 3:34 pm

    Hi, Pam!
    Here’s the answer to your question:
    Thanks for writing. 🙂

  • pam cox Says:
    January 15th, 2019 at 1:05 pm

    Why do you turn the paper side up in the crawl space instead of down like in the attic?

  • Official Comment:

    Thomas Boni Says:
    December 8th, 2018 at 4:04 pm

    Hi, Juan,
    Danny says, “I would leave it with the insulation open or you can install house wrap and staple it to the floor joist. Good luck with this project!”

  • juan Says:
    October 17th, 2018 at 7:29 pm

    After insulating my crawlspace which is exposed to the outside, should I place sheathing on the joist to encapsulate it or just leave it just with the insulation open.

  • James Smi5 Says:
    December 27th, 2017 at 2:02 pm

    Is there any to insulate under my floor beside roll up spray insulation, that type make me no matter how I dress.

  • Tiger Says:
    September 8th, 2017 at 3:10 pm

    Best advice is to not buy manufactured homes!

  • Wayne Says:
    January 6th, 2017 at 9:16 pm

    We purchased a manufactured home 14 months ago. Last year the toilet in the master bathroom stopped filling. Maintenance came and supposedly fixed the problem, but this year with sub zero temperature it has happened again. When the weather warms up the water flows again.. we put a heater in the bathroom today and the toilet is working again.
    Thru all this all the other fixtures, washing machine and toilet have worked with out ant problems. Any ideas, ANY help would be appreciated

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Insulating Floors Over a Crawl Space