Cold Floors above my Crawl Space

Have you ever wondered why your feet freeze to your bathroom floor? If you live in an older home, have you ever felt a cold draft come up through you hardwood flooring? Did you install carpet over your hardwood floors because they were too cold in the winter? Ever wonder why your floors above your crawlspace are so cold in the winter? At this point you are probably expecting an answer on how to fix your cold floors. The answer IS NOT what you are expecting. DO NOT insulate your floor. Keep reading, it gets better.

Your crawlspace is vented to the outside air, and in the winter (in the north anyways) the outside air is very cold. In the North, a homeowner is “supposed” to close his vents in the winter. Many homeowners do not know they are supposed to close their vents or they just simply forget. If the vents are not closed, freezing cold air will enter the crawl space and work against the heating system all winter long. This will cause the floors to reach arctic temperatures. Even if you close your vents, you are still drafting a lot of cold air through them. The vent is just a thin sheet of metal overlapping one another. There is not a foundation vent on the market that seals completely and none of them are insulated.

So what is a homeowner to do? You have several options. If you are a smart, energy conscious homeowner, you will seal off the outside air, insulate your vents, and encapsulate your crawlspace. This can provide energy savings of up to 10%-20%, not to mention bring your floors to a comfortable temperature. Encapsulation also will dry out your floor framing, help prevent bug infestations, and improve indoor air quality. See my post “How to insulate crawlspaces – Encapsulate and Condition” for more information.

For an example, let's say your upstairs floors are cold. Your windows on the main floor are open about 7" allowing all this cold air to come into the main floor. Would you install fiberglass insulation in your 2nd story floors and leave your windows open OR would you close all the windows. What seems to make the most sense, it's the same in the crawlspace. The difference is that you shouldn't seal your vents without encapsulating your crawlspace to seal out all the ground and foundation moisture.

The most common but INCORRECT method has been to install fiberglass insulation in the floor. Fiberglass insulation will sweat in the summer and absorb all of the moisture that is in the air of the crawlspace. When the insulation is wet, it has no insulating value. This insulation will also cause mold to grow and wood to rot. See my post “Do not use fiberglass insulation in crawlspaces” for more reasons why.

If you are looking for a cheaper and effective insulation method, you could install 2” rigid foam board along the crawlspace perimeter walls and CLOSE your vents in the winter (like you were supposed to). Just know, this IS NOT the PERMANENT SOLUTION. The only permanent solution to cold floors is to encapsulate the crawl space. We can install the foam board as a first step toward encapsulation.

For more information on preventing cold floors above your crawlspace, visit the Crawslpace Encapsulation page on our website or for a FREE EVALUATION call us at 1-877-409-2837.

Thanks for reading the rambling thoughts of a crawlspace inspector,
Larry Ralph Jr.

Crawlspace Insulating Series:
Cold Floors above a Crawl Space
Do not use fiberglass insulation in a crawl space
Foundation Vents are causing higher heating costs
Do not spray foam your crawlspace foundation walls
How to insulate crawlspaces - Encapsulate and Condition
Insulating above-grade crawlspaces - spray foam the walls

Cold Floors above my Crawl Space