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How to Encapsulate a Crawl Space (In 5 Easy Steps)

How to Encapsulate a Crawl Space (In 5 Easy Steps)

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As a result of being hidden beneath homes, crawl spaces often don’t get the attention that they deserve. As a busy homeowner, it’s easy to forget about your crawl space.

That is until bad odors start wafting into your living space or critters start to find their way upstairs. A crawl space that’s in bad shape can negatively affect your health, finances, and building structure.

Regardless of the state of your crawl space, encapsulation might be a good decision. In this article, we’ll explore how to encapsulate a crawl space in 5 easy steps. Let’s go!

What Is Crawl Space Encapsulation?

The process of encapsulation involves enclosing your crawl space using specific heavy-duty materials. The materials, used as barriers, will effectively seal your space off from the outside environment, similar to a capsule.

The primary purpose of this process is to create a better environment in the crawl space. Encapsulation leads to cleaner and drier conditions.

The chances of mold, insects, and pests decrease significantly with a clean crawl space. The risks of water damage, flooding, and additional costs of restoration are also mitigated with crawl space encapsulation.

Controlling the moisture and humidity in your crawl space is also beneficial for air quality. Crawl space encapsulation might require special permission from local authorities, depending on your area.

Advantages of Crawl Space Encapsulation

To encapsulate or not to encapsulate? Check out the benefits listed below:

  • Mold, fungi, and mildew prevention
  • Elimination of pests
  • Loss of bad odor
  • Improved air quality
  • Savings on energy bills
  • Decreased strain on the HVAC system
  • Structural protection from moisture
  • Extra storage space
  • Property value increase
  • Protection from water damage

If you don’t visit your crawl space often, you might worry about what’s going on down there. Well, the last part of the encapsulation process involves installing a dehumidifier.

This will help you monitor and maintain the humidity levels down below. The thought of having a crawl space that’s clean and well cared for will surely bring any homeowner some peace of mind — and that’s a plus!

Disadvantages of Crawl Space Encapsulation

To be fair, let’s also examine some downsides of encapsulating your crawl space:

  • High cost of construction materials, equipment, and labor
  • Requires a sizeable amount of time to plan and finish
  • Need for maintenance of crawl space conditions over time
  • Might be subject to local regulations and require a permit

Do I Need a Permit to Encapsulate My Crawl Space?

The answer to this question would depend on your area’s local building code. You will need to find the specific code that is applicable to the type of construction you plan on doing.

For example, in North Carolina, Section 106.1 of their Administrative Code and Policies requires a permit when converting a conventional crawl space with wall ventilation openings into a crawl space that’s closed.

The cost of obtaining a permit would also vary from place to place. $100– $250 would be a likely estimate.

Before beginning any work on your crawl space, it’s a good idea to visit your local regulatory department. This will help you in complying with your area’s specific building code requirements.

How to Encapsulate a Crawl Space in 5 Easy Steps

Time to encapsulate your crawl space! Here are the steps:

1 – Inspect Your Crawl Space

Before encapsulating your crawl space, you need to check on its existing conditions. If your crawl space is large or has a complicated layout, the building floor plan might help you navigate.

Here are some things to consider when performing your inspection:

1 – Land Grading

Before adding anything to your crawl space, make sure that the land under and around your foundation is properly graded. You won’t want any water from rain, snow, or even your garden hose to pool around the house.

Water can also enter the ground and enter your crawl space if your property is improperly sloped. The land grading of your property changes over time.

So, it’s a good idea to regularly check for grading issues. A downward slope directed away from the house is key to avoiding possible flooding.

If you discover that your land grading is not quite right, you can correct it by adding soil. Consulting a professional is highly recommended for this step. A land grading specialist can tell you if your slope needs fixing and what remedies are needed.

2 – Drainage System

Take a look at your gutters, downspouts, and drains. Clean your gutters to prevent them from overflowing.

Check your downspouts as well. An overwhelmed downspout that can’t handle heavy rains can exert pressure on the foundation of your home.

It can even flood your crawl space. Clogged drains also need unclogging to avoid further water issues for your crawl space.

Get rid of any puddles or standing water in your crawl space as well. Make sure that the area is dry and clean.

3 – Sump Pump (Optional)

As part of enhancing your drainage system, you might consider installing a sump pump. It’s often placed in the lowest level of the crawl space.

Its purpose is to drain and pump out any water that gets into the space. This helps keep your crawl space as dry as possible.

Installing a pump is a significant decision so you might want to consult a professional if you’re planning to do so.

4 – Mold

It’s a bad idea to encapsulate your crawl space with mold still present. If you’re smelling something musty and are experiencing allergies, there might be mold in your crawl space.

Look closely at your baseboards and other crawl space surfaces. Mold can come in different colors, such as black, green, brown, white, yellow, and even orange.

Use personal protective gear to remove the mold. Some goggles, gloves, respirators or masks, and disposable coveralls will do.

Use a mold removal spray or a mold-removal cleaner on all affected areas. Scrub away the remaining mold using a reliable brush. If the mold in your crawl space is extensive, you might want to contact local professionals who can remove the mold for you.

5 – Appliance Backdraft

A backdraft occurs when gases from combustion appliances (such as your water heater or gas furnace) reverse in flow. The gases aren’t appropriately vented.

Instead, the exhaust is pulled back into your home. Carefully inspect for a backdraft to avoid the build-up of dangerous gases inside your crawl space.

6 – Pests

Make sure to resolve any issues with termites, rats, and other pests before encapsulating. Once you’ve gotten any pest infestations under control, sanitize the area.

Thoroughly clean your crawl space of any dead critters that might cause an unpleasant odor.

7 – Structural Damage

Repair any part of the crawl space that’s damaged. This includes rotten wood and other floor sections that might need replacement.

If your crawl space has an uneven floor area, you might want to level that out. After the necessary repairs, make sure not to leave unused construction materials lying around the space.

2 – Seal the Crawl Space

Now that your crawl space is clean and all issues are resolved, you’re ready to seal the space. To prevent outdoor air from entering the space, we need to seal the vents and openings securely.

Foam boards and spray foam are the most common materials used in this step. You can use a foam board on your crawl space door as well.

Completely seal all openings. Don’t forget to seal any cracks and gaps on the floor too.

3 – Add a Thermal Barrier

A thermal barrier will make it easier to control the temperature levels inside your crawl space. Since you will need less power to heat or cool the air, this can lead to energy savings for your home.

You can use foam insulation boards for your walls. This will further block any outside air from entering.

4 – Add a Plastic Vapor Barrier

For the next step, cover the walls and floors of your crawl space with a plastic vapor barrier. Heavy-duty polyethylene is most commonly used for the job.

Note that this plastic may vary in thickness. You might want to use a thicker plastic vapor barrier on the ground than on the walls.

Measure the area properly first before cutting and installing. When cutting, make sure to leave extra material so that the plastic barrier overlaps at every seam by several inches.

Cut properly around piers and plumbing. Use a lot of heavy-duty waterproof tape or other strong adhesives.

5 – Keep Your Crawl Space Dry

Your crawl space should always be kept dry and moisture-free. The ideal crawl space humidity is between 30–60 percent.

Aim for a humidity level of 50–55 percent. To maintain the appropriate level of humidity, you will need a drying mechanism for your crawl space. A dehumidifier with a matching humidity monitor is your best bet.

Do I Need a Dehumidifier in My Encapsulated Crawl Space?

Merely encapsulating your crawl space is not enough. Even the most robust vapor barriers cannot completely prevent moisture.

Without a drying mechanism in place, the humidity in your space will fluctuate depending on the climate. It will only be a matter of time before moisture builds up.

This will cause mold, bacteria, poor indoor air quality, and other consequences. To avoid moisture build-up, a healthy humidity level must be maintained.

A dehumidifier is one of the best ways to achieve this.

Can You Encapsulate a Crawl Space Without a Dehumidifier?

Other options do exist, such as using the supply air method. This method involves blowing dry and conditioned air from your supply plenum into the crawl space.

Despite being cheaper, this choice has some serious drawbacks. Its ability to keep your crawl space dry will vary depending on how you run your HVAC system.

The air being supplied might escape into your living area and cause contamination. Also, HVAC systems aren’t designed to condition a crawl space environment.

On the other hand, a dedicated dehumidifier monitors crawl space conditions, and adapts accordingly. It’s not dependent on your HVAC system.

With a dehumidifier, there is also no risk of contaminating the air in your living spaces. On the other hand, encapsulating a crawl space without any drying mechanism at all will leave moisture levels unchecked.

As mentioned earlier, this situation can cause issues with air quality and mold, among others.

Final Thoughts

Now you know how to encapsulate a crawl space. Easy, right?

Hopefully, this article has helped you understand the process of crawl space encapsulation. As with all things, this process carries its own set of advantages and disadvantages.

You might want to consider some necessary things before getting started. See if you need a permit and consult local building code requirements.

Before encapsulation, it’s also important to keep an eye out for existing mold, appliance backdraft, and land grading issues. When everything is good to go, follow the simple steps we mentioned and you’ll be done before you know it.

After encapsulation, don’t forget to keep your crawl space dry, too. For this reason, a dehumidifier will be your crawl space’s guardian. Good luck, and don’t forget your safety gear!


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