Crawl Space Vapor Barrier

According to statistics, more than 76 million American households have a crawl space. Moisture in these spaces, however, causes challenges like wood rot and respiratory problems, amongst others.

Since you don’t access the crawl space often, you may forget to maintain it until it is too late. By then, you will notice visual damage or start experiencing discomfort. 

You can avoid these issues by having a vapor barrier. It acts as a mitigation layer that lets water out and limits it from seeping into the crawl space. 

Read on for more information about installation, benefits, costs, and frequently asked questions on vapor barriers. 

Ultimate Guide for Vapor Barriers

The process of the installation is usually straightforward. However, it’s recommended to get a well-versed professional for the job. Here are the procedures followed in the installation:

Laying the Barrier

Lay the barrier down on a flat, dry surface, measure it up, and ensure to overlap all seams. Tape the seams for maximum protection and finish off by securing the plastic at a distance of about six inches up the wall.

Covering the Exposed Foundation

With your moisture-proof insulation, cover the exposed foundation areas with a thickness of one to one and a half inches. This works as a barrier preventing the concrete’s moisture from rising into your crawlspace.


The final step entails applying rigid insulation and caulking along the rim joists. Finish off with a layer of plastic to prevent moisture and termites.

Benefits of Vapor Barriers

Vapor barriers in crawl spaces offer a list of advantages: 

Prevent foul smell and mold

Poor indoor air quality arising from mold can make it hard to relax in your home. Moreover, it’s difficult to determine whether your crawl space is the source of the foul smell. But, a crawl space barrier keeps this issue away.

Energy efficient

When your wall temperature becomes uneven, it strains your HVAC unit. But with the suitable attic vapor barriers, you get an energy-efficient home.

Protects pipes

Crawl spaces typically offer perfect room to run your electrical, HVAC, and plumbing pipework. Installing vapor barriers protects the pipes from moisture attacks that fasten exposure, risking damage.

FAQ for Vapor Barriers

When Is a Moisture Barrier Needed?

Crawl space barriers are necessary when your floor lies in a moisture-prone area. A moisture barrier prevents moisture from attacking the surface, causing damage like mold growth. 

Can I Use a Plastic Sheet as a Vapor Barrier?

Vapor barriers stop the migration of moisture through surfaces. Plastic sheets fall under the Class I vapor barriers, meaning it is one of the best barriers.

How Long My New Flooring Vapor Barrier’s Lifespan Last?

Barriers in the crawl space are installed beneath the house/floor surface. You can rest assured the barrier faces no harm exposure, serving you as long as the floor stands.

Vapor Barriers Installation Cost

One of the primary factors to consider is the installation cost. It’s essential to note the installation costs will vary depending on:

Floor size

Smaller floor sizes cost you less money for installation, and you can expect the opposite with an increase in floor area.

Moisture degree

You can expect to spend more money in wet zones as you need a thicker protective barrier to fight the high moisture. If your home is in a dry area, the moisture risk is less, resulting in a lower cost.


Having a sound vapor barrier is vital for the protection it offers your floor space. It is best to have a crawl space barrier expert install it for guaranteed results.

Insulation Co. is a leading crawl space barriers installer in the Pacific Northwest region. You can count on our experienced crew and technology to get the job done. Contact us today to get a free, same-day estimate.

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