Why Do You Need a Crawl Space Vapor Barrier?

Does your home have a crawl space instead of a slab or a full basement? A crawl space might be the best type of foundation. Unlike a slab, a crawl space provides ventilation beneath your home—as well as access to your home systems.


And unlike a full basement, a crawlspace saves energy by not needing heat or AC. However, many homeowners fail to keep up with crawl space maintenance. They end up having to deal with water incursion and other issues.

If they had installed a crawlspace vapor barrier early on, this problem might not have developed. So read on to find out how a crawl space vapor barrier could benefit you.


Why Crawl Space Maintenance Matters

Homeowners: you neglect your crawl space at your peril! Remember it is part of your house. Whatever goes on down there eventually will be noticeable up above. For example, you might start to notice a musty smell or one of feces in the air.

Either one signals a problem that probably needs professional attention. You could have vermin or an insect infestation in your crawl space. You also could have water coming in from the ground and need crawl space mold prevention services.

A crawl space mold problem or any other moisture-related concerns mean bad news. It might be time to install a vapor barrier.


What Is a Crawl Space Vapor Barrier?

A vapor barrier is a thick plastic (typically polyethylene) liner laid on top of a crawl space’s dirt floor. The idea is to prevent vapors and soil moisture from entering. While vapor barriers come in various thicknesses, yours should be at least six mil.

Even negligible amounts of crawl space moisture can lead to discomfort and inconvenience, damage and destruction, and costly repairs. The risks of crawl space moisture include:

  • Mold and mildew
  • Pests
  • Wood rot

We don’t need to tell you how these problems could affect your health or your home’s structural integrity.

Vapor Barrier vs. Crawl Space Encapsulation?

Depending on your home’s location and structure, a vapor barrier might solve all your crawl space water concerns. Often, though, this is not the case. If your crawl space has excess moisture, even after installing the vapor barrier, it might be time for “Plan B.”

Plan B, of course, refers to crawl space encapsulation. A vapor barrier only sits on top of the dirt floor and is not sealed anywhere. But crawl space encapsulation is much more thorough.

Crawl space encapsulation begins by ensuring all openings have been sealed so that air can’t get in. A thicker (12-20 mil) lining is then placed—with all seams sealed and the liner attached to the walls and columns.

Crawl space encapsulation can be a costly job, but we believe it’s worth every cent!

Sealing the Deal (and the Crawl Space)

A crawl space vapor barrier will go a long way toward controlling the moisture in many homes’ crawlspaces. But it might not solve all the problems on its own. Augmenting or replacing this barrier through encapsulation is a more comprehensive solution.

In our work, we see a lot of crawl spaces. So if you would like us to clean and inspect yours for water penetration or other damage risks, please reach out as soon as possible. When it comes to crawl space repair, you don’t want to wait.