Ashburn, VA

How Much Does Crawl Space Encapsulation Cost?

$3 – $7 Per Square Foot
$3,000 – $8,000 Average Total Cost

Crawl space encapsulation costs $3,000 to $8,000 on average, with prices ranging from $1,500 to $15,000. Crawl space waterproofing costs $3 to $7 per square foot for a drainage system, insulation, vapor barrier, repairs, sealing, and dehumidifier. A vapor barrier costs $2 to $4 per square foot to install. Get free estimates from waterproofing companies near you or view our cost guide below.

Crawl Space Encapsulation Cost

The average cost to encapsulate a crawl space is $3,000 to $8,000 or from $3 to $7 per square foot, which includes vapor barrier installation. Crawl space waterproofing costs $1,500 to $15,000, depending on the size and condition of the crawl space, accessibility, labor, repairs, and materials.

Crawl Space Encapsulation Cost Chart

Crawl Space Encapsulation Cost
Level Cost Per Square Foot Total Cost Includes
Basic $2 – $4 $1,500 – $4,000
  • Light Cleaning
  • Vapor Barrier
  • Sealing
  • No Unexpected Problems
  • No Dehumidifier
Average $3 – $7 $3,000 – $8,000
  • Basic Cleaning
  • Mold Removal
  • Thicker Vapor Barrier
  • Sealing
  • Minor Repairs
  • Sump Pump
  • New Insulation
  • Dehumidifier
Extensive $5 – $10 $5,000 – $15,000+
  • Extensive Cleaning
  • Mold Removal
  • Thickest Vapor Barrier
  • Sealing
  • Structural Repair
  • Sump Pump
  • French Drain
  • New Insulation
  • Robust Dehumidifier

*On average, labor makes up 50% to 70% of total encapsulation costs.

  • Encapsulation prevents excess moisture levels, mold growth, radon gas poisoning, and pest infestations.
  • Stops allergens and pollutants and improves indoor air quality.
  • Removes standing water, which protects your home’s foundation, posts, and floor joists.
  • Reduces energy bills by up to 20% due to better insulation.

Average Cost of Crawl Space Encapsulation Chart

Average Cost of Crawl Space Encapsulation
National Average Cost $5,000
Minimum Cost $1,500
Maximum Cost $15,000
Average Range $3,000 to $8,000

Table of Contents

  1. Crawl Space Encapsulation Cost
  2. Crawl Space Encapsulation Cost Estimator
  3. Additional Crawl Space Waterproofing Costs
  4. Crawl Space Encapsulation Pros and Cons
  5. Frequently Asked Questions
  6. DIY Crawl Space Encapsulation
  7. Hiring Crawl Space Contractors
  8. Waterproofing Companies Near Me

Crawl Space Encapsulation Cost Estimator

Basic encapsulation systems cost $2 to $4 per square foot for only a thin vapor barrier. Extensive systems cost $3 to $10 per square foot to install and include cleaning, repairs, sealing, vapor barrier, drainage system, and dehumidifier.

Crawl Space Encapsulation Cost Calculator
Steps Average Cost
Crawl Space Inspection $100 – $250
Drainage and Cleaning* $500 – $4,000
Foundation Repair* $2,000 – $15,000
Insulation Installation $1,000 – $3,000
Vapor Barrier Installation $1,200 – $4,000
Sealing Vents and Holes $150 – $450
Dehumidifier Installation $1,500 – $2,500

*Only if required. All prices are based on a 1,200 square foot space and include materials and labor.

Price estimates depend on the condition and size of your crawl space, the type of insulation, the thickness of the vapor barrier, and the type of pump and dehumidifier. The basic process to encapsulate a crawl space includes:

  1. Inspect, clean, and dry out the crawl space
  2. Repair and seal foundation, cracks, and vents
  3. Install drainage system, insulation, and vapor barrier
  4. Install dehumidifier and maintain a dry crawl space
Get free estimates from waterproofing pros. View Pros

Crawl Space Insulation Cost

Crawl space insulation costs $1.00 to $4.50 per square foot or between $500 and $3,700 for installation, depending on the type, R-value, and thickness. Spray foam insulation costs $2 to $5 per square foot, while foam boards and batts run $1.20 to $3.70 per square foot.

Crawl Space Insulation Cost
Insulation type Crawl space location Cost per square foot Total cost installed*
Closed-cell spray foam insulation Walls $2.00 – $5.00 $850 – $2,100
Rigid foam board Walls $1.20 – $3.70 $500 – $1,600
Rigid foam board Subfloor $1.20 – $3.70 $1,200 – $3,700
Blown-in Subfloor $1.00 – $2.80 $1,000 – $2,800
Roll and batt (fiberglass, rockwool) Subfloor $0.90 – $1.40 $900 – $1,400

*Average total for a 1,000 SF crawl space with 3' high walls. Removing old insulation adds $1 to $2 per square foot.

Crawl Space Insulation Cost
Type Cost Per Square Foot
Foam Board or Batts $0.40 – $1.60
Spray Foam $1.30 – $2.60
Removing Old Insulation + $0.20 – $1.00

Experts recommend spray foam insulation because it's the least likely to retain moisture and lasts the longest.

First, foam boards are installed on the walls, then covered by a vapor barrier to stop moisture from invading the crawl space. Foam boards can act alone as a vapor barrier, but are more effective when used together. Plus, insulation reduces any holes being punctured in the vapor barrier.

Crawl Space Vapor Barrier Cost

A crawl space vapor barrier costs $0.15 to $0.50 per square foot on average, depending on the thickness of the plastic, which ranges from 6 to 20 millimeters. An average vapor barrier installation costs $2 to $4 per square foot or between $1,200 and $4,000 for materials and labor.

Crawl Space Vapor Barrier Cost Chart

Vapor Barrier Cost
Thickness Average Cost Per Square Foot Cost Per Roll (1,200 SF)
6 mil $0.15 $160 – $200
8 mil $0.18 $200 – $230
10 mil $0.20 $230 – $300
12 mil $0.30 $300 – $350
20 mil $0.50 $350 – $500

*Labor costs to install add $1.50 to $3.00 per square foot on average.

Get free estimates to install a vapor barrier. View Pros

A vapor barrier is a thin plastic sheet taped down under the house that covers the ground and walls inside a crawl space to block out all moisture. Vapor barrier sealing tape costs $120 to $200 for an average crawl space.

Professionals recommend using a thicker 20-mil vapor barrier that resists tearing and lasts longer. Thin vapor barriers can tear from rocks or other debris on the crawl space floor, letting in moisture and rendering the encapsulation less effective.

Crawl Space Encapsulation With Cleaning and 20-mil Vapor Barrier

Two popular crawl space encapsulation brands are Visqueen and CleanSpace.

  • The CleanSpace® crawl space encapsulation system costs $6,000 to $13,000 total installed. It’s a 20-mil barrier with a 7-layer polyethylene composition. Authorized installers offer a 25-year warranty.
  • A Visqueen vapor barrier costs $0.06 to $0.09 per square foot. Contractors don't recommend Visqueen because it’s cheap Construction and Agricultural (C&A) grade film only lasts a few years. Stronger, engineered-film vapor barriers last up to 20 years.

Cost To Seal Crawl Space Vents

To create a conditioned crawlspace after encapsulation, a professional seals the vents and any air leaks. The average cost to seal crawl space vents is $150 to $450. Each vent cover costs $10 to $30, and most crawl spaces need 5 to 10 units.

Some contractors use the "supply air" method for ventilation, which blows air conditioning inside the crawlspace to keep it dry. Supply air involves installing a 4 to 6-inch vent in the air supply plenum. However, your crawl space only gets dry when the HVAC system is running, and crawlspace air may contain contaminants, such as radon that could infiltrate your home.

Crawl Space Waterproofing With Sealing and Vapor Barrier

Crawl Space Ventilation vs. Encapsulation

Crawl spaces with open vents are outdated and fail to keep humidity, mold, and mildew out. Builders prefer full crawl space encapsulation and sealing since it’s the most effective way to create a pest and moisture barrier. Also, sealed crawl spaces use 15 to 18 percent less energy than open vents.

Crawl Space Drainage System Cost

A crawl space drainage system costs $800 to $3,000 for installing a trench, French drains, gravel, and a sump pump. Adding a drainage system to your encapsulation is recommended in areas with a high water table or crawl spaces below ground level with water seepage.

Crawl Space Drainage System Cost Chart

Sump pump installation costs $500 to $1,200 and keeps the crawl space dry by pumping groundwater out after rains and floods. Sump pumps are an excellent preventative measure for problems like mold and wood rot.

Dehumidifier For Crawl Space Cost

A dehumidifier for a crawl space costs $800 to $1,600 for an average unit, or $1,500 to $2,500 total with installation, depending on the size of the area. High humidity areas may need a central dehumidification system that costs $1,800 to $2,000+ to purify the crawl space and the home’s first floor.

Crawl Space Encapsulation with Insulation and Dehumidifier Installation

Does An Encapsulated Crawl Space Need A Dehumidifier?

An encapsulated crawl space needs a dehumidifier to keep the area dry. Only closing the vents keeps damp air trapped that breeds mold. Some contractors use the "supply air" method to blow dry, conditioned air into the closed crawlspace, which isn't as safe or efficient as using a dehumidifier.

Using a dehumidifier in a crawl space without full encapsulation is useless because moist, outside air enters the unsealed area. A dehumidifier doesn't need to run continuously, but should keep on in wet seasons and after heavy rainfall.

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Additional Crawl Space Waterproofing Costs

Professionally waterproofing a crawl space costs $2,000 to $10,000, depending on the size and it's current condition. After an inspection, waterproofing companies may recommend repairing the foundation, installing gutters, grading the landscape, or remediating mold and radon.

Crawl Space Waterproofing Cost
Task Average Cost
Interior Waterproofing Paint $0.60 – $0.90 per square foot
Exterior Waterproofing Sealant $3 – $6 per square foot
Install Sump Pump $500 – $1,200
Install French Drain $300 – $1,500
Install Gutters Costs $4 – $8 per linear foot
Landscape Grading $500 – $5,000
Cleaning & Repairs $500 – $15,000
Permanent Water Removal $800 – $3,000
Radon Mitigation Costs $750 – $1,500
Mold Removal $500 – $6,000
Basement Waterproofing $2,000 – $6,000
Waterproofing pros near you are available to help. View Pros

Crawl Space Inspection Cost

A crawl space inspection costs $100 to $250 on average, depending on the size and if it's wet or muddy. Adding the crawl space to a home inspection costs $50 to 100 more than usual, but sometimes it's included for free. Testing for radon, mold, or asbestos adds $100 to $300 more.

Inspecting a crawl space can be dangerous and tedious, depending on the conditions and accessibility. However, it’s mandatory for a complete home inspection. If an inspector deems your crawl space unsafe, they are not required to enter, and your home can automatically fail the inspection.

A crawl space inspection evaluates:

  • Mold or mildew
  • Moisture buildup and damage
  • Termites
  • Pests or other animal infestations
  • Foundational strength
  • Leaking water and sewage pipes
  • State of exposed electrical wires
  • Ventilation status
  • Presence and state of vapor barriers

Crawl Space Cleaning Cost

Crawl space cleaning costs $500 to $4,000 on average, for remediating mold damage, removing pests, pumping out stagnant water, removing rocks and debris, and replacing damaged insulation. A light cleaning is typically included in a full crawl space encapsulation.

For minor cleaning, mold removal costs $15 to $30 per square foot with most homeowners spending $500 to $1,500 for light mold-removal and a sump pump drainage system for a 450-square-foot crawl space.

Crawl Space Repair Cost

Crawl space repairs cost $2,000 to $15,000 on average to replace parts of the foundational structure like rotting posts and sagging floor joists, replace insulation due to mold damage, repair foundation cracks, relevel the house with mudjacking, or add encapsulation.

Crawl Space Water Removal Cost

Crawl space water removal costs $800 to $3,000 for installing a drainage system in a 1,500 square-foot home that includes a trench, French drains, gravel, and a sump pump. Cleaning and sterilizing the crawl space costs another $500 to $4,000, depending on if there's mold damage.

Crawl Space Encapsulation and Waterproofing With Drainage System, Sealing, and Vapor Barrier

Water gets into a crawl space from heavy rain, flooding, foundation cracks, and clogged or misdirected gutters. Water attracts mold, damages insulation, and causes wood rot that destroys foundation beams.

Get free estimates from waterproofing pros. View Pros

Cost To Finish Crawl Space

The cost to finish crawl space is $1,500 to $15,000, depending on the size, level of encapsulation, and accessibility. The presence of mold, pests, electrical wiring, and structural issues also affect the cost. Converting a crawl space to a finished basement costs $40 to $100 per square foot.

The benefits of a finished crawl space include greater property appeal when selling, energy savings, and improved indoor air quality. Plus, it prevents the expensive costs of mold removal and structural damage repairs due to wood rot.

Basement Encapsulation Cost

Basement waterproofing costs $2,000 to $6,000 on average for drainage improvements, or between $5,000 and $15,000 for a full encapsulation with a vapor barrier. Maintaining a dry basement is necessary for the structural health of the house and preventing hazardous issues like mold and mildew.

Waterproofing a basement typically consists of:

  • Waterproofing the walls with cement
  • Sealing the foundation
  • Installing a sump pump or a drain
  • Injecting epoxy to repair cracks
  • Managing downspouts and grading the soil on the outside

Mobile Home Vapor Barriers Cost

A mobile home vapor barrier costs $0.15 to $0.50 per square foot for the material only, and between $2 and $4 per square foot for a complete installation. The Department of Housing and Urban Development insists on using vapor barriers in mobile homes to control moisture buildup issues.

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Crawl Space Encapsulation Pros and Cons

Encapsulating a crawl space solves various problems, and the benefits far outweigh the installation and maintenance costs. It's a worthwhile investment to prevent moisture buildup and keep mold, radon gas, and other airborne pathogens out of your indoor air system.

Crawl Space Encapsulation Benefits

  • Air Quality – Vented crawl spaces can no longer negatively affect indoor air quality. Cleaning and sealing the crawl space eliminates musty smells inside your home, especially with a dehumidifier system.
  • Improve Comfort – Your house won't be muggy during the summer, and room floors won’t get cold during the winter.
  • Prevents Pests and Rodents – Since pests and insects thrive in dark and damp places, a dry and sealed crawl space keeps them out.
  • Tax Rebates – Adding insulation as part of your crawl space encapsulation is an energy-efficiency home improvement that may qualify for local tax rebates.
  • Property Value – Crawl space encapsulation makes it easier to pass home inspections, maintain your home’s value, and it’s a great selling feature.
  • Mold and Mildew Prevention – Creates a moisture barrier that prevents mold and moisture from entering your home’s air.
  • Foundation Shifting – Protect your foundation’s wood from rotting and causing the foundation’s posts and joists to sink. Without crawl space encapsulation, moisture buildup makes floors warp and buckle.
  • Radon gas – Prevents radon poisoning by blocking exposure to this toxic airborne gas. Radon is colorless, odorless, and tasteless and seeps up through the foundation and crawl space to enter your interior air and water supply.
  • Save Money – Reduces energy bills up to 20 percent due to better insulation. Reduces long-term home maintenance costs, and extends the life of HVAC equipment.

Crawl Space Problems

You may notice a mild smell after encapsulation, which takes a few months to air out. This common side effect called “outgassing” comes from PVC-based moisture barriers. Sealing the inside with higher-quality and less-toxic liners, along with an HVAC system, minimizes the smell.

Homes without pH-balanced soil endure a stronger smell after encapsulation. Test your soil's pH level, then consult with a landscaper on what ingredients to add to the ground to neutralize its odors, such as sulfur or other organic compounds.

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Frequently Asked Questions

Does Crawl Space Encapsulation Work, and Worth The Cost?

Crawl space encapsulation is worth it because it reduces your energy bills by up to 20 percent and increases your home’s value. Encapsulation works to protect your home’s foundation from pests, mold, and structural damage from wood rot.

Indoor air quality can be worse than outdoor when radon seeps into the home air supply. Encapsulation alleviates health issues caused by radon, mold, or mildew since 50 percent of the air on the first floor of your home comes directly from your crawl space.

The EPA recommends using dehumidifiers in crawl spaces and basements to keep humidity levels between 30 and 50 percent maximum.

Does Homeowners Insurance Cover Crawl Space Encapsulation?

Homeowners insurance typically does not cover crawl space encapsulation. Most policies do cover water damage, such as mold removal in a crawl space and some encapsulation fees, but only if the damage is from natural disasters or unexpected events such as a bursting pipe or leaking roof.

Homeowners insurance typically covers damage from:

  1. Heavy storms
  2. Bursting pipes
  3. Faulty plumbing
  4. Leaking roof
  5. Water cleanup after extinguishing a fire
  6. AC system overflow

Only under additional flood and disaster insurance would you have coverage for all types of water damages.

Does Encapsulating A Crawl Space Increase Home Value?

Crawl space encapsulation increases a home's value and helps sell your home faster. Your home is worth more since encapsulation lowers energy bills and prevents mold, wood rot, and foundational damage. Plus, you need a clean, dry, and safe crawl space to pass a home inspection.

What's The Difference Between A Vapor Barrier And Insulation?

Vapor barriers cover the ground and foundation walls in plastic sheeting to block moisture and radon gas from entering your crawl space. Insulation inside the walls reduces the amount of moisture that enters the crawl space and helps stabilize the temperature to minimize humidity buildup.

A crawl space vapor barrier with a dehumidifier is the better solution to keep the area moisture-free. Adding insulation is also helpful in climates where the outside air temperatures rise and drop drastically.

Is Crawl Space Encapsulation Tax Deductible?

Crawl space encapsulation expenses may be tax-deductible with a sudden outbreak of mold or damage from a natural disaster. Ask a tax advisor how to itemize expenses on IRS Form 4684 to claim a deduction. The 30% federal government tax credits for crawl space encapsulation expired in 2010.

Also, the Federal Residential Energy Property Credit for installing insulation in an attic or crawl space ended in 2018. Ask your local tax advisor if your state or city offers any tax rebates or incentives for home improvements.

Can You Fill A Crawl Space With Concrete?

The U.S. Department of Energy has concluded that concrete walls or floors are not a substitute for encapsulation since concrete is porous, and moisture travels through it. For these reasons, even concrete basements can benefit from some type of encapsulation system.

Still have questions? Ask a waterproofing pro. View Pros

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DIY Crawl Space Encapsulation

A crawl space encapsulation do-it-yourself project is difficult and even dangerous. You may develop serious health issues due to mold exposure and damage the structural foundation with an incorrect process. Hiring professionals to repair and clean a crawl space that's been damaged costs more than just hiring contractors upfront.

DIY Crawl Space Encapsulation Kits

A full crawl space encapsulation kit to seal 1,200 square feet costs $1,200 to $2,800 on average. Expect at least 10 hours for two people to encapsulate a 1,200-square-foot crawl space. Kits often come with:

  • Dehumidifier: $800 to $1,600
  • 800 Feet of Liner Seam Tape: $120 to $200
  • 1,200 Square Feet of Vapor Barrier Liner: $180 to $600
  • 10 Vent covers: $100 to $270
  • 4 Spray Foam Cans: $20 to $140
  • Polyurethane Sealants: $6 to $12 each

Misapplying the liners or failing to set up proper ventilation causes serious long-term moisture problems and harm your house’s foundation. Plus, there may be exposed electrical wires, loose pipes, pests, and allergens to tackle within a tight space.

How To Encapsulate A Crawl Space

The process of installing a crawl space encapsulation system in 4 easy steps:

  1. Clean, repair, and dry out the crawl space.

    A crawl space must be free of pests, mold, and moisture before encapsulation. Drains and sump pumps help to stop future water accumulation, and sometimes foundation repairs are needed.

  2. Install insulation and vapor barrier

    Contractors spray foam insulation on the walls, then seal off the crawl space by lining a vapor barrier to the floor, walls, piers, and equipment. Crawl spaces with a gas furnace may require rerouting the gas lines.

  3. Seal off all remaining cracks and openings.

    Contractors seal all vents, openings, and cracks 1inside the crawl space to prevent humid air from entering. Polyurethane sealants or extra spray foam creates an airtight seal.

  4. Maintain a dry crawl space environment.

    Contractors install a dehumidifier to keep moisture out of the crawl space. Another option is to open the vents once a year to flush out any airborne toxins that could accumulate.

Before DIY, get free estimates from waterproofing pros. View Pros

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Hiring Crawl Space Contractors

Hiring professional help is the safest and most cost-effective method, especially with older homes. Crawl space contractors prevent many problems and make sure it meets building code requirements. Choose specialized companies over general contractors and be sure to:

  • Get at least three in-person estimates to compare.
  • Ask for recommendations from family, friends, and neighbors.
  • Read reviews and check out their previous work on HomeGuide, Google, and the Better Business Bureau (BBB).
  • Ask for a full itemized contract in writing in case of a dispute.
  • Avoid making large payments upfront. Never pay in full or in cash, and come up with a payment schedule for work completed.

Questions To Ask Crawl Space Companies

  1. Can I see a portfolio of your prior work?
  2. Are you licensed, insured, and bonded?
  3. Who's the project manager, and will you use subcontractors?
  4. What hours do you and your crew work?
  5. Do you offer a warranty?
  6. What’s your payment schedule?
  7. Does my crawl space need vents or any repairs?
  8. Does my crawl space meet code requirements? (Door, insulation, etc.)
  9. Is there sufficient clearance between the foundation and soil?
  10. Do you use air-blocking caulks and sealants?
  11. Can you test the radon levels in my crawl space?
  12. Will you use a vapor retarder on the bare ground of the crawl space?

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