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How to Warm Floors Over Dirt Crawl Space

Are you struggling with how to keep your floors warm over your crawl space? Many homeowners are being told not to insulate their crawl space. Then they call us and have a legitimate concern about cold floors.

Insulate the Crawl Space

The first step in warmer floors is to make sure you properly insulate the crawl space. If you have a vented crawl space, we recommend batt insulation installed between the floor joists. Since your vents are open, it is a good idea to insulate plumbing pipes too.

If you have a closed crawl space, insulating between the joists is acceptable but we recommend insulating the foundation wall for even more comfort. Normally plumbing pipes are more protected, so insulating them may not be necessary if your crawl space is encapsulated.

image of crawl space insulation batt insulation

Radiant Floor Heat

Making your floors warm means they need to be warmer than your body temperature. Radiant heating floor systems are a great way to do this depending on your flooring. Installing insulation as stated above will not make your floors warm. It will make them warmer than not having insulation. Dehumidifiers are not good at warming floors either. Click here to see a video we made about that.

Should I Remove Insulation from Crawl Space


Air Seal the Crawl Space Sub-floor

Get yourself some spray foam and go to work air sealing all major penetrations in the sub-floor. This will cut down on drafts and should be done on vented and closed crawl spaces. We don't recommend spray foaming the entire sub-floor system. This can trap moisture from high humidity. It can also create wood rot from leaks around toilets and other plumbing in the living space.

Is Spray Foam Good for My Crawl Space Sub-floor


Do you need help insulating your crawl space or basement? If so, we can help. Please contact us to schedule your assessment. Also, let us know in the comments below if you'd like to suggest a future blog post.

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About Michael Church

Michael Church has been involved with indoor air quality since 2005 and feels the unhealthy crawl space is one of the major problems causing poor indoor air quality.


  1. Karen Simms on February 4, 2023 at 12:02 pm

    Should the paper side of the batt insulation be on the subfloor side or the crawlspace side, or does it matter which side?

    • Michael Church on February 8, 2023 at 2:55 pm

      Insulation manufacturers recommend paper face the living space so the subfloor side.

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