Do I Need a Vapor Barrier in My Crawl Space?

The crawl space under your home is more important than you might think.

You may wonder, “Do I need a vapor barrier in my crawl space?” Well, you’re in the right place to learn the answer.

Somewhere between 15% to 20% of all homes in the United States have a crawl space. A crawl space costs less to build compared to a full basement. However, it’s more functional than a slab.

You most likely don’t spend a significant amount of time in your crawl space. Resultantly, you probably don’t mind much if it’s damp or musty.

Still, the condition of your crawl space is very important. Flooring and insulation alone aren’t enough to protect your home.

For the answer to the question, “Do I need a vapor barrier in my crawl space?”, keep reading.

Do I Need a Vapor Barrier in My Crawl Space?

Let’s get right to the point. Yes. You need a vapor barrier in your crawl space. What’s more, a moisture barrier is the minimum amount of protection that you should have in your crawl space.

A vapor barrier helps you to avoid expensive repairs. Without the right care and maintenance, such as a vapor barrier, your foundation can sustain considerable damage.

A vapor barrier is a plastic liner. It covers the dirt in your crawl space. More importantly, it blocks vapors and moisture in the soil from entering your crawl space.

A vapor barrier is important for a couple of reasons. Firstly, the air in your crawl space enters your home.

Your home is made of porous materials, such as wood, concrete and fiberglass insulation. Also, in part, the air in your HVAC unit circulates air from your crawl space into your home.

Problems in your crawl space can enter your home. This is especially problematic if someone in your home is managing a respiratory condition.

In addition, porous materials do more than allow air to circulate. They also allow moisture in your crawl space.

contractor installing vapor barrier in crawl space

Why You Need a Crawl Space Vapor Barrier

You cannot maintain a healthy home when excessive moisture is present. Damp air encourages mold growth.

It also forces your HVAC unit to work harder. Moisture also decays your wood flooring and home structure.

Once the wood in your home starts to deteriorate, it attracts insects. In fact, soft, moist wood is a delicacy for termites.

You may already have a vapor barrier in your home. However, when is the last time you checked your vapor barrier?

A vapor barrier is not a one-and-done installation. The average moisture barrier only lasts 5 to 10 years. Eventually, a vapor barrier starts to break down and deteriorate.

Accordingly, it’s a good idea to take a peek into your crawl space to check the condition of your vapor barrier. If that idea doesn’t sound appealing, a skilled contractor can handle the job.

If your vapor barrier is failing, you’ll notice an immediate improvement in air quality after installing a new one. The air will fill less humid.

Also, any musty orders will dissipate. In addition, you’ll notice that you pay less for monthly utilities.

Signs of Trouble in Your Crawl Space

If there’s water in your crawl space, it’s a sign of a big problem. A vapor barrier is not sufficient to handle pooling water in your crawl space or basement.

A vapor barrier stops moisture. However, they do nothing to stop water.

Pooling Water

Pooling water renders a vapor barrier completely ineffective. If there’s pooling in your basement or crawl space, you’ll need further measures, such as encapsulation or a sump pump.

Falling Insulation

Also, you’ll need to rid your crawl space or basement of falling fiberglass insulation if you’re having moisture issues. In some cases, you may notice a substantial amount of crawl space insulation has fallen out of place. Professional crawl space vapor barrier installers also know how to insulate a crawl space.

Cold Floors

Also, you might notice that you have cold floors in the winter. In these instances, you may want to consider an alternative to fiberglass insulation, such as spray foam.

Even after these steps, you could still notice that the air in your home feels clammy. In that case, you may also want to look into a humidifier for your crawl space or basement.


Finally, mold is another serious issue in basements and crawl spaces. If you find mold in this area, have it inspected by a professional.

It’s possible that the mold is toxic. If so, it will most certainly require professional remediation.

It’s important to remediate water damage early. Early remediation helps to mitigate the devastating effects of water seepage. However, not all signs of water damage are obvious.

It’s a good idea to hire a crawl space professional to inspect your basement or crawl space for this reason. Expert crawl space vapor barrier installers can help to shield your crawl space and home from water damage.

There are a few telltale trouble signs that could mean you have a crawl space moisture problem that requires professional attention.

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Fix Crawl Space Issues Now to Avoid Structural Problems Later

Basements and crawl spaces are damp and dark. As a result, they’re ideal environments for mold growth. Mold growth is a clear sign of water seepage.

If you see mold in your basement or crawl space, it’s a good idea to act fast. A quick intervention will keep mold from spreading to other parts of your home. A professional remediation service can help you to keep mold at bay.

Swelling is another example of a big crawl space problem. Wood swells when it gets wet because wood fibers absorb moisture. The moisture makes timber expand.

If you see swelling in the wooden parts of your walls and floor in your crawl space or basement, you most likely have a seepage issue. Eventually, moisture can spread to other parts of your home, making doors and windows hard to open and close.

crawl space contractor preparing to install vapor barrier

The Vapor Barrier Installation Process

Vapor barrier installation is straightforward for a trained professional. They’ll begin the process by removing any loose debris and grading your crawl space. This step is an important part of insulating a crawl space with a dirt floor.

Many companies will skip the grading part of crawl space vapor barrier installation. It’s the hardest part of the job. Here’s the difference between a reliable professional and a contractor who just wants to complete the job as quickly as possible.

It’s important to provide a solid flat base for a vapor barrier. Without grading, clumping and other issues will cause a vapor barrier to perform undesirably.

Next, the contractor will need to make measurements. They’ll also check for any obstacles to laying down the vapor barrier.

Here’s another area where experience and quality of work come into play. Without experience, it’s difficult to ensure a good fit for the poly sheeting used for the vapor barrier.

The contractor will then prepare the sheet with the cutouts made for obstacles. Now, they’ll lay it down as tightly as possible.

When installing a vapor barrier, the goal is to achieve as close to 100% ground cover as possible. Any exposed area of dirt can lead to potential problems.

How Do I Fix the Problem?

By now, the clear answer to resolving a moisture issue in a crawl space or basement is to have a moisture barrier installed. The question that remains, however, is how to find the right professional for the job.

Firstly, you’ll want to look for crawl space vapor barrier installers with a valid contractor’s license. The company or contractors should have an up-to-date license with your municipality.

You can check a potential service provider’s website for this information. Alternatively, you can ask them to show you the license when they come to provide you with a quote for the job.

You also want to make sure that potential crawl space vapor barrier installers are insured. Contractor insurance protects you from liability if something goes wrong.

You’ll also want to make sure that a service provider has sufficient experience. You can ask a contractor for referrals from past clients. You can also check crawl space expert online reviews to see what other people have to say about working with a given contractor.

Finally, you’ll want to look for a service provider who stands behind their work. A basement and crawl space expert who knows how to do a great job will have no problem providing you with a warranty.

Crawl Space Experts to the Rescue

Now you know the answer to the question, “Do I need a vapor barrier in my crawl space?” What you need now is the best crawl space and basement service in your area.

Crawl Space Medic takes moisture and mold seriously. We can help you identify the source of moisture problems and provide a long-term recommendation.

Moisture and mold can make your home unhealthy. We’ll assess your crawl space and provide you with the best solution to ensure your long-term health.

Our experienced crawl space vapor barrier installers have decades of expertise. They know how to bring your home to repair and safety.

Keep your family safe. Contact Crawl Space Medic today at (866) 882-7295 or connect with us online to schedule an inspection.


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