Should I insulate my crawl space?

The answer to that question is undoubtedly YES! The real question is HOW should I insulate my crawl space. The scary thing is that if you asked 10 contractors the question of HOW, you would receive 10 different answers. There are many different methods to insulating a crawlspace and some are effective, but many methods are disastrous. I am not going to write a lengthy post on the many different methods, that will come later. This is about what a homeowner must do BEFORE they insulate their crawlspace.

The original reasoning behind insulating a crawl space floor was because we were venting cold winter air into the crawl space that was keeping our floors cold and freezing our water pipes. As a result, builders decided to insulate the floor joist cavities with fiberglass. For the past couple of decades, the idea has been to close the vents in the winter and open them in the summer. The general insulation method for the past 30 years or more has been to insulate the floors AND the walls. This brought the temperature of our floors from 0 degrees to around 40 degrees. Still not exactly comfortable, but it has kept us from losing our toes to frost bite. It also helped reduce frozen water lines; therefore also aiding in the reduction of the suicide rate of plumbers. This short, brief history on insulating methods is mainly Midwest specific and has been generalized to keep from boring you to death. The only thing that matters is that as an industry, we learn and improve on our past mistakes and successes.

For the past 5 to 8 years depending on where you live, you might have heard of a process called crawlspace encapsulation or crawlspace conditioning. Crawlspace Encapsulation is a process whereby the crawlspace ground and wall is completely “encapsulated” or sealed by a heavy duty plastic liner. The liner is fastened and sealed to the foundation wall, and the seams of the plastic are overlapped and taped. The vents in the foundation are insulated and sealed air tight. The crawlspace is then conditioned with heat duct leakage and/or openings; or in some cases air is drafted from the living area into the crawlspace. Basically, you are turning that nasty, musty, dirt crawlspace into a healthy, clean, living environment. Encapsulating also prevents mold growth, reduces humidity, helps keeps out bugs, prevents wood rot, and reduces musty odors. Check out our website for all the advantages of encapsulating your crawlspace: http://www.americanbasementsolutions.com/crawlspace-repair.html

Hopefully, I haven’t lost your attention yet. The first thing you should do before insulating your crawlspace is encapsulate your crawlspace. Studies have shown that encapsulating your crawlspace alone can save between 10% - 20% on your energy bills. No method of insulation, bad or good will outperform encapsulating your crawlspace. Insulation can be added to the walls and in the band board pockets (between the floor joists against the outside walls) after or during the encapsulation process. Insulation will perform according to its maximum potential after the crawl is sealed. You wouldn’t add insulation to your home’s walls and ceiling in hopes of lowering your heating bills if all your windows were opened all winter long. You would close your windows air tight, AND THEN insulate your walls. To put it bluntly, it is extremely, extremely stupid to insulate before you encapsulate.

Thanks once again for reading the rambling thoughts of a crawlspace inspector,

Larry Ralph Jr.

Should I insulate my crawl space?