Insulating Floor Over Dirt Crawl Space

insulate crawl space

Should I Insulate the Floor Over My Dirt Crawl Space?

People ask me all the time if insulation is necessary in the crawl space. If you are thinking of insulating the floor over a dirt crawl space, we recommend you think about the long term of what you will be doing with the crawl space. If you plan to encapsulate the crawl space your insulation procedure may be different than if you are planning to keep it vented or open to the outside.

Don’t Insulate Your Crawl Space

To us it is comical that there are crawl space companies out there telling people not to insulate their crawl space. Why would they say this? The fact is international residential building code requires crawl spaces to be insulated so when you pay someone to encapsulate your crawl space and they do not install crawl space insulation that's the same as paying an electrician to install wires not to code. Would you do that?

Remember doing something to code is considered the minimum of what should be done. So many crawl space companies are not even doing the minimum requirements to making your crawl space healthy and energy efficient.

Insulating a Vented Crawl Space

If you would like to keep your crawl space vented because you live in a low humidity environment we recommend insulating the crawl space floor with fiberglass or rock-wool mixed with spray foam for air sealing. This will give you the thermal barrier between the crawl space and your living space as well as help keep the air from getting from the crawl space into the living space. Remember up to 50% of the crawl space air can transfer into the living space.

Insulating During Crawl Space Encapsulation

You can also insulate the floor of the crawl space and the sub-floor of the crawl space if you live in a cold environment. Insulation on the dirt floor may be useful but in Tennessee we find this not to be so. If we are performing crawl space encapsulation and we feel the insulation needs to be removed due to water or mold damage, then we recommend insulating the walls of the crawl space to keep the cold out of the crawl space in the winter and the warmth out in the summer. This will make the crawl space better conditioned and more energy efficient.

Insulating the crawl space and air sealing the sub-floor along with rim joist insulation and air sealing is a great way to make sure your entire home is energy efficient. We hope you enjoyed this article please let us know if you have any comments below. Also, please contact us if you would like a free crawl space inspection.

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.