How Much Does Crawl Space Encapsulation Cost?

• Typical Range: $1,500 to $15,000
• National Average: $5,500

For decades, homeowners were told crawl spaces had to be vented to encourage fresh air to circulate beneath the home and keep humidity from building up. While that worked—to an extent—it didn’t do much to protect the underside of the flooring system in regions that see high humidity levels. In those areas, the humidity of the outside air is the same as the humidity in the crawl space.

The purpose of crawl space encapsulation is to keep the home’s floor system dry and healthy by completely blocking humidity. Crawl space encapsulation costs range from around $1,500 for small crawl spaces up to as much as $15,000 for encapsulating a large crawlspace or one that needs repairs. The national average cost of encapsulating a basement is $5,500. A home is only as sound as its foundation, so encapsulation—especially if you live in a humid region—will be an investment in your home’s lifespan.

What Is Crawl Space Encapsulation?

Crawl space encapsulation is the process of sealing the underside of the house to keep moisture away from the floor joists and the subflooring. It can be accomplished using several methods and materials. The difference between sealing a foundation and crawl space encapsulation is that traditional foundation sealing is done outside the foundation walls. In contrast, encapsulation takes place on the interior of the crawl space.

While the national average cost of encapsulating a crawl space is $5,500, this figure will vary between communities based on several factors. This is a project best left to professional foundation contractors since errors here could result in trapping moisture that could damage the structure. When considering crawl space encapsulation pros and cons, it’s essential to factor in the project’s cost versus the benefits. In most cases, the benefits will outweigh the price.

Factors in Calculating Crawl Space Encapsulation Cost  

Crawl space encapsulation is limited in scope, meaning it’s restricted to just the area beneath the house. But the final cost is dependent on multiple factors, such as the quality of the materials used, the size of the crawl space, whether a permit and inspections are necessary, and if other procedures are required to protect the foundation. The contractor who does the work will examine the existing crawl space and recommend a specific material. The contractor will also determine whether the crawl space should also be insulated. Homeowners can generally expect to pay between $3 to $7 per square foot for the project.

Materials and Labor

The total cost of materials and labor to complete a crawl space encapsulation ranges from $1,500 to $15,000. That vast price difference is due to the going cost of labor in a community and the quality of the materials used—for example, installing a single thin layer of plastic liner will run less than installing multiple layers or adding a draining system.

Crawl Space Size and Condition

Before a crawl space can be sealed, it must be free from debris, and it should be in good structural condition. Repairs can cost anywhere between $1,500 and $15,000, depending on the extent of the fix required.

Permits

Many communities require pulling a permit for crawl space encapsulation projects because if they’re done incorrectly, they could negatively impact the home’s structure. The cost of a permit varies from community to community but, in general, will run from $100 to $250. When a contractor takes out a permit, the information is recorded on the homeowner’s property details so the county can maintain a record of improvements.

Inspection

When a permit is required to do the project, an inspector will probably schedule a time to come out and look at how well the contractor has performed the work. The cost for this type of inspection is typically included in the cost of pulling the permit.

If homeowners are unsure whether crawl space encapsulation is necessary, they can have a contractor come out and inspect the space. These inspections are often free.

Foundation Waterproofing

If the crawl space foundation is currently leaking or has multiple cracks, the contractor may recommend waterproofing it, adding about $4,600 to the project. Waterproofing runs the gamut in price because no two foundations are identical. If the foundation is in decent shape, it could cost as little as $600, but if waterproofing requires installing gutters or drain tile, the cost could exceed $10,000.

Wall Insulation

In some areas, insulating the crawl space makes sense to help maintain a uniform temperature and reduce the risk of sweating in the crawl space. Installing batt insulation runs an average of about $300 to insulate a large crawl space and is the most cost-effective material. In contrast, spray foam insulation can run from $0.50 to $1.50 per board foot. A foundation contractor can recommend the best type of insulation for your home and budget.

Vapor Barrier Installation

The vapor barrier is the most crucial element in crawl space encapsulation projects because it blocks humidity and moisture from coming into contact with the underside of the home. The cost of a crawl space moisture barrier ranges from about $0.50 to $0.70 per square foot, depending on the quality and thickness of the barrier. Thickness is measured in millimeters, and the thicker the vapor barrier, the more it will cost.

Vent Sealing

All existing crawl space vents must be sealed to ensure dryness in an encapsulated crawl space. Other gaps and air leaks into the crawl space must be sealed as well. Covers for crawl space vents are relatively inexpensive, running about $15 to $22 apiece. The typical crawl space has one vent for every 150 square feet of interior crawl space.

Drainage System

Encapsulation of the crawl space will keep humidity from the underside of the house. Still, if water is pooling around the bottom of the foundation, it could eventually cause the foundation walls to shift. If it’s necessary to collect the water and pump it away, a sump pump may need to be installed. The average cost of installing a sump ranges from $650 to $1,800, with most homeowners paying about $1,300.

Dehumidifier

In homes in very humid regions, adding a dehumidifier may be necessary to keep the crawl space air dry. Installing a dehumidifier will add $800 to $1,200 to the final cost. If a dehumidifier is called for, it may also be necessary to install a sump pump because a dehumidifier removes water from the air, and the water needs a place to discharge.

Additional Costs and Considerations

Like basements, crawl spaces can host many unsavory things, such as insect and rodent infestations or extensive mold growth. Existing problems must be addressed before the foundation contractor can seal the crawl space against moisture and humidity. Depending on the type and extent of the issue, it will undoubtedly increase the final cost.

Drainage, Repair, and Cleaning

Water and foundations don’t mix, and in some cases, improving drainage will be more extensive than just installing a sump pump. It could involve repairing foundation cracks at the cost of $2,025 to $7,100 on average or installing a complete interior drain system for $700 to $5,200. If the house needs new gutters and downspouts (to carry water away from the foundation), it could add an average of $1,050.

Pest and Mold Removal

Pests, whether rodents or bugs, should be removed before encapsulation. The same holds for mold. If these problems are not fixed, they could become worse hidden under the vapor barrier. Mold and pest removal runs from $500 to $6,000, depending on the extent of the problem.

Finishing

It will cost between $40 and $100 per square foot to convert a crawl space into a finished area. The price will depend on the accessibility, size of the crawl space, and amount of encapsulation needed. A finished crawl space can increase a home’s property value and be more attractive to potential buyers.

Do I Need a Crawl Space Encapsulation?

High humidity levels in a crawl space can lead to several problems. If you’re experiencing any of these issues or live in a region where the humidity is high, you might want to consider encapsulation.

“Sweating” Windows

When moisture builds up on a home’s windows and runs down, it indicates high humidity levels in the house. This can result from several issues, but if moisture is entering the home through the crawl space, that’s the likely culprit. Running a dehumidifier will stave off interior damage, but consider encapsulation for a long-term fix.

Mold and Pest Problems

Mold thrives in a damp environment, but it’s not the only thing that likes moisture—termites and other pests also like it. A wet crawl space with pooling water will attract all manner of rodents and bugs who don’t have to travel far to get a drink, and the longer the moisture problem exists, the bigger the infestations can become.

Musty Smell

Smells and odors tend to seep from one floor of a home to the next and can travel through a home’s HVAC system, so if your house smells musty, find out where the smell is coming from. If it’s coming from the crawl space, encapsulation could help remediate the problem.

Inefficient Heating and Cooling

The temperature of a room indicates how comfortable it feels, but it’s not the only indicator. The most comfortable humidity level ranges from 30 to 50 percent. A wet crawl space can increase the humidity level in the living areas of the home, which can make you feel sticky and sweaty. In addition to cooling, the AC unit works to remove humidity from the air, so the higher the humidity level, the harder the AC unit has to work.

Indoor Allergy Symptoms

Everyone wants to breathe clean, fresh air, but it’s vital for those who suffer from allergies. The presence of mold spores in the air can trigger allergy symptoms in anyone, including itching, a runny nose, burning eyes, and respiratory problems. If the spores originate in the home’s crawl space, having the problem professionally remediated and then encapsulating the crawl space may ease the symptoms.

Drafts and Poor Temperature Control

Not only does crawl space encapsulation protect the underside of the home from moisture, but it also seals out drafts and adds a measure of insulation. This will make the living area in the home more comfortable, and it will also help reduce heating and cooling costs since the air temperature in the crawl space will have a reduced effect on the living space.

Benefits of Crawl Space Encapsulation

A house is typically the single most significant purchase most people will ever make, so doing whatever is necessary to protect that investment makes sense. Reducing moisture along the foundation and the area directly below the house is a critical step in maintaining the home’s overall integrity. Homeowners can add another layer of protection that will safeguard their house while making it a healthier place in which to live.

Better Indoor Air Quality and Comfort

Sealing the crawl space from outdoor air will reduce the moisture entering the crawl space, reducing the risk of musty air seeping up through the floor into the living space. Many crawl spaces in new construction homes do not have vents, but older homes likely do, so they will need to have those vents sealed at the cost of $15 to $22 per vent cover (labor not included). Without drafts flowing from the crawl space into the home above, the comfort level will also increase.

Insect and Pest Infestation Prevention

There’s no guarantee pests won’t find a way to enter the space between the vapor barrier and the foundation walls, but if they do, that’s where they’ll remain. The encapsulation process completely seals off the crawl space from outdoor air and critters, so they can’t munch on the home’s structural elements or spread diseases.

Mold and Mildew Prevention

In a new home that sits on a crawl space, encapsulation can prevent the homeowners from ever having to deal with a mold or mildew issue. In an existing home with established mold growth, the mold will be removed and the structure treated to prevent additional regrowth before the vapor barrier is installed. Removing the mold could cost anywhere from $500 to $6,000, depending on the extent of the problem.

Better Energy Efficiency 

Open, vented crawl spaces tend to get icy cold in winter and sweltering hot during the summer, and then the cold or heat transfers through the floor into the home. Crawl space encapsulation can improve your home’s energy efficiency up to as much as 20 percent, and with skyrocketing utility costs, that’s good news for all homeowners. Using less energy also reduces the home’s carbon footprint.

Tax Rebates and Higher Property Value

Since encapsulation increases energy efficiency, it may qualify for local or state energy incentives or tax rebates. In addition, anything that improves the air quality in the home and reduces the risk of moisture damage will likely increase the home’s property value and be a beneficial selling point.

Radon Gas Poisoning Prevention

Radon gas is the product of decomposing organic matter in the soil, and it can rise through a home’s foundation. While it’s not a problem in all regions, having your home’s crawl space encapsulated will help ensure healthy indoor air if you live in an area with high concentrations of radon gas. Radon gas is odorless and tasteless, so air-quality testing is the only way to detect it.

Foundation Protection

During the foundation contractor’s inspection of the crawl space, a determination will be made as to whether the foundation will require additional drainage measures, such as installing an internal floor drain or other repairs that will keep water away. These may include but are not limited to grading the yard, so water runs away (at the cost of $1,400 to $5,200), repairing foundation cracks (ranging from $2,025 to $7,100), or installing new gutters and downspouts to direct water away from the foundation (at the cost of $600 to $1,550).

Crawl Space Encapsulation Cost: DIY vs. Hiring a Professional 

Rather than searching for “crawl space encapsulation near me,” enthusiastic DIYers might think they can save a lot of money by encapsulating and installing a vapor barrier in crawl spaces. But attempting this project isn’t recommended. All the materials needed to complete the project are readily available from home improvement centers or online. Still, care must be taken to completely seal the crawl space to prevent outside air from getting in, or you end up with worse moisture problems than before. Additionally, if you DIY the project, it doesn’t come with a warranty or any type of guarantee, so if there’s a problem later, you’ll be on the hook to pay for all of the repairs. The complementary parts of the project, like installing a dehumidifier or sump pump, also aren’t DIY-friendly projects as there are many moving parts that are best left to a professional.

How to Save Money on Crawl Space Encapsulation Cost

By having your home’s crawl space encapsulated, in the long run, you’ll have lower utility costs, your home’s structure will be protected, and the comfort level indoors will increase. However, spending an average of $5,500 is a pricey prospect for many, especially those on a budget. Here are a few ways you may be able to save a little money on the cost of crawl space encapsulation.

• Clean the crawl space yourself. This isn’t a fun job for many because it entails scooting (depending on head space) between the floor joists and the ground and clearing away debris, insects, and rodents. However, you stand to save a chunk of change if you do this part yourself.
• Purchase the materials. Contractors will buy all the necessary materials to complete the project, but they will typically tack on a service fee of about 10 percent of the cost of the materials.
• Ask about a package deal. Contractors may offer a cut on their services if you purchase more than one service up front. If you’re thinking of putting on an addition, you might get a cut on the cost of encapsulation if you have the same company pour the new foundation walls.
• Choose less expensive materials. For example, it costs between $3 and $7 to have a crawl space insulated. Having batt insulation installed will come in at the bottom of the pricing structure, while opting for spray foam insulation could be twice as expensive.

Questions to Ask About Crawl Space Encapsulation 

An encapsulation project can be lengthy, and because a foundation can have extensive problems, it’s essential to ask the contractor some questions at the first meeting. That way, it’ll be simpler to understand what you’re getting for your investment.

• Can I have a bid?  Asking this is essential because a bid is a set-in-stone price that the contractor agrees not to exceed. An estimate is just a ballpark figure that could (and likely will) go higher.
• Will you itemize the bid? It’s not an imposition to ask this of a contractor. It’s vital to be able to compare what different contractors are offering. If you get more than one bid (and you should), one contractor may have included a thicker vapor barrier than the other, but you won’t know if the bid isn’t itemized.
• Do you offer financing? If you don’t ask this question first, the contractor will assume you’re prepared to pay for the whole thing upon completion. If your budget is tight right now, but you want to protect the crawl space, some companies will allow you to make payments for up to 2 years.
• Do you see any urgent structural issues with my crawl space or foundation?
• How long will this project take?
• What kinds of caulks and sealants do you use?
• Should I insulate my crawl space?
• Does my crawl space need ventilation?

FAQs

Having the crawl space encapsulated will not only protect your home’s structure, but it will also make the living space more comfortable and energy efficient. If you’re thinking about selling the home in the next few years, it can also be a significant selling point. Still, it’s not an inexpensive project, ranging from about $1,500 to $15,000, and it’s normal to have a few questions.

Q. What’s the difference between a vapor barrier and insulation?

A vapor barrier blocks humidity and keeps moisture from entering the crawl space. Insulation is made to reduce thermal transfer, reducing the amount of heat or cold that can seep through. A sealed crawl space does provide some insulating effect by preventing outdoor air from blowing through the area.

Q. Is crawl space encapsulation worth the cost?

Many homeowners feel it’s well worth the national average cost of about $5,500 to protect the integrity of their home’s structure and ensure the value of their property. For those who live in humid regions that see a lot of mold, mildew, and water damage, it’s a better investment than it is in drier areas. In arid regions, it likely won’t make a difference.

Q. Is crawl space encapsulation necessary? 

Crawl space encapsulation is becoming more popular all the time as it helps homeowners protect their crawl spaces, but it’s usually not required by building codes. A good foundation contractor can tell you whether it’s the best option for your home. If your home is in a humid area where many new homes are now built on slab foundations rather than crawl spaces, it could be because there’s a risk of damage to a crawl space from excessive moisture.

Q. Is crawl space encapsulation covered by insurance? 

Like other crawl space and basement remedies, encapsulation is likely not covered by your homeowners insurance policy. However, check to see if local or state tax rebates apply, because the project is energy efficient.

Q. How much does it cost to encapsulate 1,000 square feet of crawl space?

On average, the cost to install a crawl space encapsulation system runs between $2 and $4 per square foot, so the cost to encapsulate a 1,000 square-foot crawl space would run an average of $2,000 to $4,000. The final price will depend on the quality of materials (vapor barrier) used and whether additional crawl space repair is necessary.

Q. How long does crawl space encapsulation last?

A quality encapsulation project will last approximately 15 to 20 years, but it’s not unheard of for encapsulation to last upward of 20 years. The project’s ultimate useful life will depend on several factors, including how efficiently the encapsulation prevents moisture from entering and whether an outside event—such as flooding—occurs to reduce the encapsulation’s efficiency.

Q. Does an encapsulated crawl space need a dehumidifier? 

Not necessarily, but it never hurts to install one. Adding a permanent dehumidifier with a hose that discharges water to the outside of the house is more important in regions where the humidity is high. In other areas, just the encapsulation itself is often sufficient for protecting the home and improving indoor comfort.

Sources: HomeAdvisor, HomeGuide, The Spruce