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What Is Crawl Space Encapsulation

Crawl spaces are really convenient for some larger appliances and subpanels, but sometimes you would prefer to pretend the space doesn’t exist. But just because crawl spaces are commonly damp and moldy does not mean that they have to stay that way.

A crawl space can be made functional through encapsulation. It works as a form of waterproofing that deals with humidity and mold, but it’s a process (in varying extensiveness) requiring a lot of careful work and a fair amount of money. But if you want to control humidity, this is your best option, and it has a list of benefits that make it worth it.

Encapsulating a crawl space is a process of sealing the space, fitting white plastic sheeting to the walls and floors, and conditioning the air therein to deal with humidity and standing water. It is a process designed to control humidity levels in the crawl space as well as mold and mildew issues.

Encapsulation Is a Form of Waterproofing

Crawl spaces are notorious for holding a lot of moisture. Encapsulating your crawl space involves sealing the space to help reduce the humidity levels and prevent leaking. But primarily, the point of the process is to insulate the crawl space against humidity.

Thick sheets of polyethylene are used to line the floors and walls, while vents are sealed, and conditioning is done to protect the crawl space against moisture and prevent the growth of mold and mildew, and any pest problems.

NASATEK Double Bubble White/Foil Reflective Insulation (500sqft = 48ft Wide X 125ft Long) Roll Metal Building, Concrete Slab, Pole Barn, Crawlspace, Basement, Ceiling, Wall, Radiant Flooring ETC

What Does Encapsulation Involve?

  • Preparation: clear the area and level the floor to create the best possible seal and prevent damage to the encapsulating layers.
  • Sealing: all external openings (vents, ducts, wiring) need to be sealed for waterproofing and to stop external air from entering the crawl space. You need to make sure you seal any gaps or cracks as well.
  • Conditioning: this step is once the crawl space is sealed and covered, you need to remove the moisture that is already in the space. This is done with a dehumidifier or vents that filter the humidity away from the crawl space. A sump pump is installed.

WAYNE CDU1000 1 HP Submersible Cast Iron and Stainless Steel Sump Pump with Integrated Vertical Float Switch - 58321-WYN2

Drainage systems are important to sealing a crawl space, and this is essential in locations where you experience flooding.

Encapsulation vs Vapor Barriers

Encapsulation and vapor barriers are both intended to reduce moisture in an area, in this case, a crawl space.

EncapsulationVapor Barriers
White plastic on walls and floorsBlack plastic on floors
Space is completely sealedVents are not sealed
Dehumidifying is neededNo dehumidifier required
Sump pumpNo sump pump

While both serve similar purposes, encapsulation does so more thoroughly. You can find a more detailed comparison in Difference Between Encapsulation and Vapor Barrier.

Encapsulation vs Insulation

Encapsulation is meant to deal with moisture, while insulation is used to deal with frozen pipes and cold floors.

Seal the space entirelyRecommended to seal the area if there are no ducts or appliances in the space
Lay vapor barrier on the walls and floorsInsulate the walls or ceiling and add a vapor barrier to the floor if there are appliances in the space
Reduces humidity and moldControls thermal transfers to improve heating

While they can seem similar in process, encapsulation and insulation have different functions. Insulation will not decrease the humidity in a basement, and the same is true for a crawl space.

Benefits and Drawbacks of Crawl Space Encapsulation


  • Helps to reduce and prevent humidity and moisture.
  • Prevents mold and mildew, decreasing health risks.
  • Prevents pest infestation.
  • Makes the space more hospitable.
  • Reduces utility bills.
  • Reduces the energy usage of your HVAC system.
  • Helps to preserve your structure and its stability.
  • The airtight seal helps improve the air quality in the area.
  • Protects your insulation from getting wet.
  • The additional finishing helps the resale value of your house.
  • Control odors.
  • Space can be used for storage.


  • It is expensive.
  • You cannot encapsulate a space that is not entirely sealable.
  • The crawl space must be completely sealed.
  • It can require a lot of preparation work in terms of drainage, mold, and appliances that can cause a dangerous backdraft.
  • You will have to replace old wall insulation.
  • You might need to upgrade or update your HVAC system.
  • There are maintenance costs to an encapsulated crawl space.
  • Any dehumidifier you use will likely need servicing.

For a more detailed look at the benefits and drawbacks of encapsulation, read through my dedicated Pros and Cons of Crawl Space Encapsulation article.

Is Crawl Space Encapsulation Necessary?

There is no law requiring encapsulation of a crawl space. Therefore, it is not necessary to do so. However, the benefits of the process are often reason enough to take on the project.

Encapsulating your crawl space helps with the heating and cooling of your house, without having to employ additional methods like installing an expensive crawl space heater (standard, cheaper space heaters are pointless in a crawl space).

The moisture and the damage that moisture can cause to appliances and your house structure is also mitigated, and it would help with what you are not allowed to do with a natural crawl space.

It would mean you can install a subpanel in the crawl space because it would be protected from many conditions that would prevent the installation, such as wet and flooding, dust, and dirt.

Cost of Encapsulating a Crawl Space

The cost of your crawl space encapsulation is determined by the size and condition of your crawl space as well as the contractor and materials you use.

There are three categories to the cost of encapsulating your crawl space, and they depend on what you need to do, i.e., cleaning, repairs, and barrier installation.

  • $1,500-$4,000: this is for a basic encapsulation that requires minimal preparation and additional conditioning without any complications.
  • $3,000-$8,000: this is the price range for a standard encapsulation, including addressing mold and small repairs and installing sump pumps (important for areas prone to flooding).
  • $5,000-$15,000: this cost range covers the need for extensive cleaning, repairs, drainage systems, and the thickest barriers.

An estimation of the average cost is $7,500.

However, it is helpful to know that labor is going to make up half or more of the price. Should you decide to do this project yourself, you can go through the process in full and get quality materials for a fraction of a professional fee.

You may find it more convenient and expedient to hire a team of professionals to encapsulate the crawl space, or you may be keen to do it yourself. If you are, you just need some time, grit, and a few essential materials.

Materials for DIY-ing Your Encapsulation

Amazon sells the barrier sheeting (NASATECH White/Foil Vapor Barrier (amazon link)) and seam tape for the vapor barrier (ELK Vapor Barrier Tape (amazon link) is listed for crawl spaces).

There are some tools you will need to complete this project as well:

  • Drill and/or masonry bits. The GOXAWEE Cordless Drill (amazon link) is a good all-round electric drill and comes with a masonry drill bit.
  • Protective eyewear. The DEWALT Safety Goggles (amazon link) are a good choice here, or you can go for the popular MEGIX Safety Goggles (amazon link), which have adjustable frames and temples and fit over glasses.

You can always outsource a couple of the more complicated aspects of the job, such as installing drainage and structural repairs and complete the rest of the project yourself.

How Long Will Encapsulation Last?

500sqft NASATECH (6 Mil Reinforced Scrim) White/Foil (Waterproof) Vapor Barrier 4ft x 125ft Encapsulation Pier Wrap Crawlspace Insulation (White/Foil) Solid Super Strong Reinforced Scrim

With the correct materials, no corners cut, and good quality work, you can expect your encapsulation to last around 15 years. With the quality of products that are currently available, you may even get to 20 years.

You are guaranteed good work with a reputable professional service, especially if they offer warranties for their work. A DIY project will rely on how thorough you are with the process and the type of materials you use.

If you are looking to get the longest lifespan out of the encapsulation, or you are unsure about the process at any point, you may want to call in a contractor instead of completing the crawl space yourself.

Can Dehumidifiers Be Used Instead of Encapsulation?

You cannot use a regular dehumidifier in a crawl space because it cannot endure the environment and will not be able to filter the air at the rate necessary, which means that a heavy-duty dehumidifier would be needed. Even still, professionals tend to agree that a dehumidifier without encapsulation is pointless.

However, if your crawl space is encapsulated, the dehumidifier would not need to survive the elements as the area is sealed against these. The encapsulation also reduces the amount of humidity that sits in the crawl space. This means that you might be able to use a regular dehumidifier in a well-ventilated crawl space.

If the crawl space lacks sufficient ventilation, then the International Residential Code, in Section R408.3, requires a heavy-duty dehumidifier to be used.

If you have appliances in the crawl space, you might need to install a more robust dehumidifier to help maintain good air quality in the crawl space, but it depends on your particular circumstances and setup.


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