Why Crawl Space Encapsulation: Benefits, Negatives, & Costs


If you’re here reading this article, a home inspector or a pest control technician has probably mentioned that you should consider a crawl space encapsulation system.

You probably have a lot of questions. What is a crawl space encapsulation system? How much does encapsulation cost? What are the benefits (or negatives) of a crawl space encapsulation system? Can you encapsulate your crawl space yourself?

Crawl Space encapsulation is used to turn damp crawl spaces into clean, dry, and mold-free space. Damp crawl spaces cause structural problems, pest activity, and mold growth. Crawl space encapsulation is a thick, tear-free plastic barrier that works with a commercial-grade dehumidifier to keep crawl spaces dry, pest-free, and mold-free.

Experts can list dozens of reasons why you should consider encapsulating your crawl space, and it may be beneficial for your health and your property’s value.

In this article, we’ll be discussing crawl space encapsulation in detail. We’ll discuss and answer your questions, including:

  • Why crawl space encapsulation?
  • How much it costs to encapsulate a crawl space?
  • What are the benefits (and what are the negatives) of encapsulating crawl space?
  • Whether you can encapsulate a crawl space on your own?
  • How long does the encapsulation take?
  • Does encapsulation add value to your property?

Let’s get started!

Why Crawl Space Encapsulation?

Moisture problems are widespread in houses with crawl spaces. If your crawl space is dry, consider yourself fortunate. Crawl spaces are generally damp spaces. It’s not unheard of to have moisture levels of over 70% during the summer months. If the wood moisture content in your crawl space is over 18%, you are susceptible to wood rot and mold growth.

Moisture problems in crawl spaces can be caused by a multitude of factors. The main contributing factors to damp crawl spaces include:

  • The ductwork in the crawl space producing condensation during the summer months.
  • High groundwater levels during rainy seasons.
  • Poor lot drainage allowing water to flow into the crawl space.
  • Undetected plumbing drain leaks that allow water to settle inside the crawl space.

If you have a damp crawl space you likely have problems with the following:

  • Mold growth on the insulation and wood floor structure. Mold growth is present in the wood when wood moisture levels are higher than 20%. Over time, wood dry rot and decay sets in, causing potentially thousands of dollars in property damage.
  • Foundation cracks form when the house settles. Settlement typically occurs when wet soil compacts, soil erosion occurs, or due to poor perimeter drainage.
  • Termites and other wood-destroying organisms are attracted to damp areas and moist wood. Damp crawl spaces are a perfect environment for these organisms to thrive.
  • High heating and cooling costs are common in homes with damp crawl spaces because the HVAC systems have to work harder to achieve the desired comfort level.
  • Windows sweating on the interior in homes with damp crawl spaces. This is because damp, humid air from the crawl space rises to the home’s interior, where it condensates on the windows caused by radiant heating.

Repairing damage caused by these items far outweighs the cost of an encapsulation system. The time to encapsulate a crawl space is before the problems exist or at least before they become major problems.

How Much Crawl Space Encapsulation Costs?

It isn’t easy to accurately estimate how much encapsulation can cost. Crawl space encapsulation costs are based on several factors including:

  • The square footage of the crawl space. Materials such as the plastic vapor barrier are priced by square footage. Also, you may need multiple dehumidifiers depending on the size of the crawl space.
  • Depending on the drainage around the home, you may require a french drain system with roof gutters.
  • Depending on the groundwater levels around your home, you may need one or multiple sump pumps.

HomeGuide states the national average is about $3000 to $8000, with prices topping $15,000 for larger houses.

HomeAdvisor states that the national average is $1500 to $15,000, with a median price of $5500.

That means that an average crawl space encapsulation cost is about $5,000 – materials and labor by a professional contractor included. However, the average prices can range more like $5,000 – $10,000 per job. for an average of about $8750.00

According to Acculevel, The average crawl space size is 1500 to 2000 square feet. At an average cost of $3 to $7 per square foot, a 1500sf house can cost $4500 to $10,500, making the average cost more like $7500.

A 2000sf house can cost $6000 to $14,000, making the average cost more like $10,000.

This also may not include french drains, sump pumps, etc. Let’s find out what exactly determines the price of encapsulation.

Contractors often suggest insulation based on your crawl space’s size and ventilation. Foam insulation boards cost between $0.50 to $2 per board foot for the side walls. Fiberglass batt prices can go from something like $2 to $4 per square foot. When your contractor starts installation, they will cover foundation walls in a rigid, R-valued foam board and install insulation.

Vapor barriers also make up for a large portion of the price. A 20-millimeter thick vapor barrier can cost from $0.50 to $0.70 per square foot. The tape to secure the seams costs about $50 for a 4″ by 180-foot roll. It’s better to put this, rather than thin 6-millimeter plastic.

People tend to choose the plastic over the vapor barrier because it’s cheaper, but it’s also thinner – meaning that it can rip open and compromise the work. A thicker plastic barrier resists tearing, which is needed to keep out moisture.

The charges for installing a vapor barrier depends on the crawl space size. A crawl space contractor’s quote will include all labor and materials. A vapor barrier is a plastic sheet (it can be anything from 6 to 23 millimeters in thickness) that lines the ground and wall of a crawl space to restrict moisture from entering.

After all the leaks in your crawl space have been fixed, your contractor will install the encapsulation. Following this, they need to seal exterior vents and air leaks. Vent covers can usually be bought online, prices varying from $15 to $22.

However, contractors often cut a rectangular piece of insulated board to close off vents and spray foam insulation to seal air leaks around the vents and foundation wall penetrations. Air conditioning from the inside may help keep the area dry, so your contractor may install vents that help with this.

The drainage system around your home is critical, especially if you’re living in an area with a high water table. Your contractor may suggest you install a sump pump as part of your encapsulation system – about $1,100 (on average). The pump itself isn’t that expensive, anything from $60 to $170 for a pedestal version, and submersible pumps usually cost from $100 to $400.

The pump needs to be powerful enough to keep up with heavy rainfall. The sump pump needs to sit in a bucket with an airtight lid to prevent water from pooling and evaporate back into the crawl space is also necessary.

An encapsulation system is not complete without a commercial-grade dehumidifier. Dehumidifiers may cost anything from $780 to $1,500 – without installation. Commercial-grade dehumidifiers are large and built for higher moisture levels.

A popular model among contractors is the Santa Fe Compact70 Dehumidifier for Crawl Space and Basements.

Before the encapsulation even begins, the crawl space has to be cleaned. Mold and moisture damage can build over the years. Repairs can cost anything from $1500 to ten times that much, depending on the severity of the repair needed. Wood rot to floor structures, foundation settlement, sagging floors, or mold remediation issues is the most expensive to repair.

Rocks and other debris need to be removed from the crawl space so the vapor barrier can lay flat and not rip on sharp objects. Total project rates usually include the removal of rocks and debris.

Finally, an encapsulation system can also feature alarm systems to alert homeowners when a leak occurs in the crawl space.

Benefits of Encapsulating Crawl Space.

Humidity is a problem every household faces. Depending on your geographical positioning, your humidity can be high or low. This doesn’t happen when your crawl space is encapsulated.

Encapsulation Prevents Moisture Problems

Encapsulated crawl space reduces or eliminates moisture problems in the crawl space. The goal of encapsulation is to maintain relative humidity below 60% in the crawl space regardless of the outdoor humidity. With a dehumidifier, humidity levels are routinely less than 50%. This is more hygienic and ensures the longevity of the structure. Mold and humidity are bad for wood, and it will cause problems that may be hard to solve in the long run.

Encapsulation Prevents Pest Infestations

This can also help prevent future pests. There are many places infamously known for high humidity, Charlotte (North Carolina) is one place. Many faunas thrive in humid areas, but you will likely witness a drop in the number of termites and rodents when you encapsulate your crawl space.

Encapsulation Saves on Energy Costs

You will undoubtedly feel the effect of crawl space encapsulation in your pockets – and I don’t mean the overall cost of the encapsulation process. After you encapsulate your crawl space, you’ll be losing less heat to bad ventilation and poor airflow. This means that you’ll spend less on your utility bills. The Advanced Energy studies have found nearly a “20% reduction in energy use in homes with a conditioned crawl space”. 1

Encapsulation Prevents Musty Odors

The noticeable absence of foul odors is another benefit of having your crawl space encapsulated. Crawl spaces are one of the most significant contributors to foul smells, and after you get all those pesky spaces sealed – you’ll be getting rid of those mold and mildew odors.

Encapsulation Improves Indoor Air Quality

Your overall air quality will drastically improve. This is because mold can’t freely roam around your house. The issue with crawl space isn’t just that it’s full of mold; it’s also that it has unsealed openings that allow mold spores to freely glide around your house, causing health issues, smells and helping more mold grow.

Once you’ve successfully encapsulated your crawl space and sealed those openings, even if mold does grow (which it likely won’t), it won’t be spreading throughout your house. Gasses released by soil as well as dust and allergens are also effectively blocked.

Negatives of Encapsulating Crawl Space.

Despite all the benefits of crawl space encapsulation, it doesn’t come without its negatives, and unfortunately, most of these negatives will hit your wallet.

Encapsulation is not Cheap

The most prominent negative that deserves to be pointed out is that encapsulation is a costly process. Not every home needs encapsulation, but many homeowners still decide to go through with it. Most homeowners save money by installing a 6-millimeter plastic vapor barrier to protect their home’s wood structure from moisture.

Although many homes need to encapsulate their crawl space, many homes don’t, and this process will only hurt their pockets. This is probably the most significant disadvantage of this process.

Many homeowners who looked at this as their first solution to a damp crawl space are now looking back in buyer’s remorse, thinking that they could have gone with cheaper options for the same effect. However, if you’re facing serious issues with crawl space mold and humidity, then this may be the best option and could have saved you money long-term with offset structural repair costs.

Encapsulation May Require Additional Insulation

Another disadvantage of going through with this is that you may have to have foundation wall insulation. Some contractors will recommend additional rigid foam insulation on the inside of the foundation walls. We’ve discussed these costs above.

Other than the cost, rigid spray foam insulation can hide termite activity. Many contractors cover the masonry walls as well as the wood beams. It’s recommended if spray foam is being added to discuss the risk of termites and if leaving the wood exposed is preferred.

Encapsulation May Require HVAC Upgrade

Encapsulation can also lead to more expenses in the form of upgrading your HVAC system. Encapsulated crawl spaces will limit the amount of free-flowing air in your house. Your current HVAC system may require more airflow to function properly. You might need to upgrade your HVAC to keep your house’s temperature at a stable and consistent level.

This should also include an inspection of your ductwork to ensure there aren’t any leaks that may harm your new upgrade. Chances are, your ductwork was a contributing factor to the moisture problems in the crawl space and may need to be replaced.

If your present air handler or gas furnace is located inside the crawl space and your ductwork needs replacement, consider moving the HVAC outside as a package unit or, if possible, into the attic with new ductwork. It is recommended if you can get the ductwork out of the crawl space, do it.

Encapsulation Requires More Maintenance

After encapsulating the crawl space, you will likely need to do additional maintenance. This depends on the number and kind of features you installed during the encapsulation. Additional maintenance can include maintaining gutters, sump pumps, etc. Maintenance costs can add up to more than what you’d be paying without the crawl space encapsulation.

You may not see a return on investment on encapsulation for those who live in an area that doesn’t see a lot of rainfall (such as in the southwest). The main benefit of sealing out moisture won’t be realized because you have low rainfall levels and your crawl space is already dry and moisture-free.

Dehumidifiers Require Routine Maintenance

Lastly, the dehumidifier will need regular service to run correctly. The dehumidifier should be serviced at least once a year. Dehumidifiers have filters that need to be cleaned or replaced. Also, dehumidifiers in crawl spaces use a condensate pump to push moisture to the crawl space’s exterior. Condensate pumps can become clogged, which will require service to clear.

However, all of these disadvantages need to be taken with a grain of salt. There are many advantages that, in my opinion, overshadow the disadvantages – I’m once again appealing that you consult an expert and have them take a look at your crawl space before you make any big decisions.

Can You Encapsulate Crawl Space Yourself?

Encapsulation is not a DIY job. A lot goes into a crawl space encapsulation, and even with 2 or 3 workers on site, it can still take several days to complete. While there’s nothing that says you can’t do this yourself, you need to be aware that this is not a one-person job and can take you several days to complete. You should ask yourself, can you do it as well as a professional?

Most professionals will advise you not to take this project on yourself. To quote Home Advisor, “Encapsulation is a job for a professional. Do not try this as a do-it-yourself project.” – however, a lot of people are skeptical about this, as they think that professionals would prefer that you exclusively call them about this job, instead of doing it on your own (if you’re capable of doing so).

I’m afraid that I may disappoint you and recommend that you listen to the experts and let them do the job.

However, if you do decide to do it yourself, it is possible.

Time to Complete: You’ll need 8-10 hours per two people per 1,000 square feet

Tools You’ll Need:

  • Plenty of lighting: flashlight, headlamps and/or utility lamps
  • Utility Knife
  • Drill with masonry bits
  • Measuring tape
  • Trash bags
  • Marker
  • Rubber paint roller 

Protective Gear You’ll Need:

  • Coveralls
  • Work gloves
  • Protective eyewear
  • Knee pads

Materials You’ll Need:

  • Crawl space vapor barrier or retarder
  • Vapor barrier seam tape
  • Double-sided construction tape
  • Dehumidifier
  • Condensate Pump
  • Masonry Screws

Steps to Encapsulate Your Crawl Space Yourself

Access Your Crawl Space

The first thing you want to do is assess your crawl space. Take a careful look at the foundations and the walls. If necessary, take pictures. You’ll need to measure everything (and I mean everything). Measure the height of the foundation walls and measure the perimeter to calculate the crawl space square footage.

Clean the Crawl Space

Following this, you’ll need to clear everything out. It’d be terrible to invest money in materials, only to have them rip on a rock or something else. Using a rake. start at the farthest point from the access door and begin raking debris. Carry a 5-gallon bucket or large trash bag to collect debris as you make your way back to the access opening.

Order Supplies to Begin Encapsulation

After you measure your space, you need to order the materials you’ll be needing. You can purchase most of the supplies (seal tape, barrier material, etc.) locally. The supplies are available from Lowes or Home Depot.

However, the commercial-grade dehumidifiers may have to be ordered online, depending on where you live. Santa Fe dehumidifiers are amongst the most popular brands, so you should look them up. I recommend the Santa Fe Compact70 Dehumidifier for Crawl Space and Basements.

You’ll also need a condensate pump to use with the dehumidifier. I recommend the Little Giant 554415 VCMA-15ULST Automatic Condensate Removal Pump with Safety Switch and 20-Feet Tubing

Prepping the Vapor Barrier

Cut the barrier material into pieces to cover each corresponding wall. You’ll want to cut the pieces slightly larger than you need and overlap them when installing, so there are no gaps. Cut the vapor barrier in your yard or home (not in the crawl space).

Start Installing the Vapor Barrier

The first thing you’ll do after cutting all your materials to their proper measurements is to add double-sided seal tape along the foundation walls just under the floor joists. After that, attach the plastic vapor barrier along the foundation walls, keeping the vapor barrier as consistent as possible.

Insider Tip: Carefully pressing down against the wall using the rubber paint roller to seal the tape’s vapor barrier.

This part usually takes another person to pull off, so you’ll need to get a partner to finish it. After doing this, repeat the same process with the floor. Overlap the seams by a few inches. Tape all the seams. Use the rubber paint roller to seal the tape on the vapor barrier seams.

Don’t forget to seal any vents or windows that you might find. The access door needs to be completely airtight, as well.

There are many tutorials on YouTube that can help you out if you’re having trouble envisioning this.

Install the Dehumidifier

All you need to do now is provide the encapsulated crawl space with a dehumidifier. According to experts, it’s best to keep the humidity level between 45% and 55%. Santa Fe dehumidifiers are amongst the most popular brands, so you should look them up.

The biggest reason I would advise everyone to hire a professional to do this job is that you’ll likely need to run a GFCI outlet to the location you intend to install the dehumidifier. Also, most contractors will generally offer a warranty for a typical crawl space encapsulation project.

If you do the job on your own, you have to repair the potential damage and cover your expenses. When you have a contractor’s warranty, they’ll repair everything and cover their expenses. After all, you, as an amateur, can’t guarantee your work, while professionals can.

How Long Does It Take to Encapsulate Crawl Space?

The process of encapsulation shouldn’t take too long. This can be done over a single weekend. You’ll need 8-10 hours per two people per 1,000 square feet. The issue is everything that comes beforehand.

Firstly, you need to clear out the mess. If you’ve just moved to a new home, you have already experienced copious amounts of cleaning hours and hours of taking care of someone else’s mess. This is the same thing, but much worse. It’s damp, dirty, messy, and a bit claustrophobic.

After cleaning everything out, you’ll measure the space. Waiting for the materials you’ve ordered usually doesn’t take too long, but those are the standards that we got used to before a global pandemic. Now, it’s not so simple to order anything, and you may have to wait a while.

Once your materials arrive, you can get to work. And, as I’ve said, the job itself usually doesn’t take more than two days with a worker partner.

Does Encapsulating Crawl Space Add Value?

Encapsulation is progressing towards becoming a standard for all crawl space homes in the USA. As the public becomes more educated on the subject, the demand is rising in the housing market, and homeowners who have encapsulated their home’s crawl space have increased their homes market value in some markets.

Improved interior air quality along with less indoor humidity during the warmer months. Better ambient interior temperature stabilization. Warmer interior floors, especially those rooms with hardwood or tile. 

By doing this, you’re ensuring the safeguarding of your family’s health – this is another reason houses with encapsulated crawl space have more value than the opposite.

I’ve already mentioned that these houses have fewer problems with pests of all kinds. You would not believe the charges pest control will charge you for cleaning this sort of space. Not to mention that your house’s longevity is drastically improved.

Having your crawl space encapsulated, or encapsulating it yourself, is a move you should think about, but make sure to do it carefully. This process is right for you, your family, and your house, whether you intend to live in it or flip it for profit.

However, it would be best if you were careful when deciding to go through with this, since in some places, it may be a complete waste of money, as some areas don’t require crawl space encapsulation because of their low humidity rate.

When doing this, try to get professionals to do this job for you instead of doing it yourself. Contractors know what they’re doing, and they’re going to do a better job than you ever can. If you’re looking for a long-term return of profit, you’ll feel the benefits of crawl space encapsulation on your monthly utility bill and other things, as well.

HomeInspectionInsider.com is owned and operated by Hubert Miles is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com. HomeInspectionInsider.com also participates in affiliate programs with other affiliate sites. Hubert Miles is compensated for referring traffic and business to these companies.

Hubert Miles

I've been conducting home inspections for 17 years. I'm a licensed Home Inspector, Certified Master Inspector (CMI), and FHA 203k Consultant. I started HomeInspectionInsider.com to help people better understand the home inspection process and answer questions about homeownership and home maintenance.

Recent Posts