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What Is Crawl Space Encapsulation? (Plus the Pros and Cons)

What Is Crawl Space Encapsulation? (Plus the Pros and Cons)

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As a contractor, one of the most frequent questions I receive from homeowners is, “What is crawl space encapsulation, and do I really need it?”

Crawl space encapsulation is the process in which a crawl space is encapsulated—or sealed— with a heavy-duty polyethylene barrier to help regulate the moisture levels in the area.

The polyethylene barrier covers not only the floors but also the walls and ceiling of the crawl space.

In this article, I’ll answer everything you need to know about crawl space encapsulation, including its pros, cons, and costs.

Let’s dive right in!

Is Encapsulation of a Crawl Space Necessary?

Encapsulating a crawl space isn’t necessary, but it’s highly recommended to improve the living condition and air quality of your home.

Not only that, but it’ll also improve the structural integrity of the crawl space’s foundation and prevent mold growth as well as water damage.

Why Encapsulate a Crawl Space

Encapsulating a crawl space comes with multiple benefits, including:

  • Preventing water damage
  • Preventing the growth and smell of mold and mildew
  • Preventing “sweaty” windows
  • Reducing the risk of pest infestations due to excess moisture
  • Reducing heating and cooling costs
  • Strengthening the foundation of the crawl space
  • Improving the air quality of the home

Adding crawl space encapsulation is well worth the investment, especially if you consider the value it brings to your home.

With the help of crawl space encapsulation, you can effectively eliminate any moisture issues that may arise in the future, such as mold and mildew.

Exposure to mold and mildew can cause health problems in some people as they can trigger allergic and respiratory symptoms, so encapsulating a crawl space is an easy way to protect your home from either situation.

In addition, crawl space encapsulation reduces foul odors in your home. After having been professionally cleaned and sealed, your home will smell clean from the inside out.

What Should the Humidity Be in an Encapsulated Crawl Space?

The humidity in an encapsulated crawl space should be between 30 and 60%, depending on the temperature.

The encapsulated crawl space should neither be too humid nor too dry, as a dry crawl space can cause dry rot while high humidity can cause the growth of dust mites and wood rot fungus.

The encapsulation process alone helps maintain good humidity levels in your crawl space.

This is because apart from sealing the vents and surrounding area, the process involves addressing any and all water-related issues by installing a proper drainage system, such as a sump pump, and a high-quality vapor barrier.

As such, you’ll rarely have problems with the humidity levels of your crawl space when it’s encapsulated.

That said, encapsulating a crawl space doesn’t 100% solve the humidity issues in the home, especially if you live in a humid area.

Adding an energy-efficient dehumidifier to your crawl space is a great idea, even if it’s already encapsulated. It’ll ensure your humidity levels stay at a proper range to prevent humidity-related damage.

What Are the Pros and Cons of Crawl Space Encapsulation?

Encapsulating a crawl space is most beneficial, but there are several disadvantages that might dissuade you from having it installed. Let’s take a look at both:

Pros of Encapsulating a Crawl Space

Here are some advantages of encapsulating a crawl space:

Prevents Moisture Damage

The biggest advantage of crawl space encapsulation is that it prevents moisture from seeping into your crawl space.

When left unchecked, moisture can do a significant amount of damage to your crawl space. It can compromise the structural integrity of your home’s foundation, as it can cause joints and beams to wrap, expand, and crack over time.

A crawl space that has been damaged by moisture can be incredibly expensive and time-consuming to fix. Encapsulating your crawl space relieves you of this burden.

Prevents Mold and Mildew

Moisture can cause mold, fungus, and mildew to grow on wood, which not only results in wood rot but also compromises the air quality of your home.

Encapsulating your crawl space prevents such growth by maintaining proper crawl space humidity levels and preventing moisture build-up.

Similarly, it eliminates the foul odor produced by mold mildew because the encapsulation process includes cleaning and prepping the crawl space for sealing.

Reduces Heating Costs

When you encapsulate a crawl space, you’re adding an extra layer of insulation to your home.

This insulation keeps outdoor temperatures out so your heating system won’t work twice as hard to maintain stable temperatures.

You’ll no longer be losing air to your crawl space because it’s sealed up nicely.

Insect and Pest Infestation Prevention

Encapsulating a crawl space prevents insects—particularly moisture-loving insects—from breeding underneath your walls.

If there’s no moisture in the crawl space, they’re less likely to reside there.

Furthermore, the encapsulation process completely seals off the space from external elements, preventing insects from outside to enter the crawl space.

Increases Property Value

Because it reduces moisture-related damage and helps with home insulation, crawl space encapsulation can indirectly increase the property of your home.

This makes an encapsulated crawl space a beneficial selling point that some buyers might find attractive.

Additional Storage Space

Another less-mentioned advantage of crawl space encapsulation is that it adds usable storage space to your home.

Most people avoid storing their stuff in the crawl space of their basement because it’s prone to moisture issues and easily gathers dust, dirt, and insects. By encapsulating the crawl space, you’re essentially creating a dry and sanitary environment to store all your items.

Cons of Encapsulating a Crawl Space

These factors might make you think twice before encapsulating a crawl space:

High Upfront Cost

Perhaps the biggest disadvantage of encapsulating a storage space is its high upfront cost. Crawl space encapsulation can cost anywhere between a modest $1,500 to a jaw-dropping $15,000, with a national average of $5,500. It’s definitely an investment and a high one at that.

The cost of encapsulation depends on many factors, including materials and labor, crawl space size and condition, permits, and overall inspection.

If the crawl space’s foundation is leaking or has multiple cracks, the contractor must waterproof it before performing the encapsulation, adding another ~$500 to 3,000 to the project depending on the damage.

Some might even suggest installing wall insulation to further improve the effectiveness of the encapsulation.

Remember: encapsulating a crawl space isn’t only about sealing the surrounding area. It’s also about making sure the crawl space is clean and moisture-free for years to come.

Maintenance Costs

Like any other home improvement project, a crawl space encapsulation must be regularly maintained to ensure its effectiveness.

The cost of maintenance depends on the number of features you installed during the installation, but it usually costs around $300 to $400 annually.

This wouldn’t be so much of an issue if the crawl space returns the investment by protecting your valuables during heavy rain.

But you might find it too costly to install and maintain if your area doesn’t experience a lot of rain or moisture.

HVAC System Issues

Encapsulating a crawl space limits the airflow in your home, which can be an issue if your home is running an older combustion-based furnace. When you install a crawl space encapsulation, you might need to upgrade your HVAC system to ensure it’s running efficiently.

How Much Does Crawl Space Encapsulation Cost?

The cost of encapsulating a crawl space depends on many factors, including:

  • Crawl space size
  • Crawl space condition
  • Quality of materials
  • Labor
  • Permits
  • Inspection
  • Additional projects (cleaning, wall insulation, foundation waterproofing)

Naturally, a larger crawl space costs more to encapsulate than a smaller crawl space. Additionally, the crawl space must be in good structural condition before any sealing occurs.

Repairs alone could cost anywhere between $1,500 and $10,000, depending on the damage that needs to be repaired.

On top of that, most states require a permit for encapsulating a crawl space because, if done improperly, the encapsulation can adversely affect the home’s structure. Permits cost another $100 to $250 and can take weeks to acquire.

Other projects associated with crawl space encapsulation include foundation waterproofing, wall and vapor barrier insulation, and vent sealing. In areas that experience frequent flooding, the installation of a dedicated drainage system like a sump pump might be necessary.

Drainage, cleaning, pest and mold removal, and certain repairs don’t come in the package. You’ll have to pay for these services separately before encapsulating your crawl space.

Overall, crawl space encapsulation costs anywhere between $1,500 to over $15,000. It’s a major project that needs time, investment, and a professional hand to complete.

Final Thoughts

Crawl space encapsulation is the process of sealing the surrounding area of a crawl space with heavy-duty polyethylene. It’s done to reduce humidity and moisture-related issues such as leaks, mold, mildew, pest infestation, and wood rot.

Though expensive, encapsulating a crawl space is well worth the investment if you live in a high-humidity area or an area that experiences frequent snow and rainstorm. It improves your energy efficiency and prevents damage to your home, which in turn increases the long-term value of your property.


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