Crawl Space Encapsulation Cost Calculator
Cost data last checked September 28, 2026.
Full encapsulation of a 1,200 sq ft crawl space typically costs $3,200 to $11,900, with these lines included: Crawl space dehumidifier, installed.
Typical cost for this job$3,200 - $11,900From published national cost guides, checked on the date above the calculator. Sources are listed below it.
1. Size of the crawl space
Floor area: 1,200 sq ft. For an L-shaped crawl space, use the outside length and width and expect the real figure to come in a little lower.
2. What the job includes
| Scope | Typical cost, this size |
|---|---|
| Vapor barrier only (floor) | $3,200 - $8,300 |
| Full encapsulation (floor, walls, sealed vents) | $3,200 - $11,900 |
Both totals use the size above and whatever you tick below. Pick a scope to see it broken out further down the page.
Scope
The EPA recommends keeping indoor relative humidity below 60%, ideally between 30% and 50%. If a hygrometer under your house reads higher than that, tick standing water above or mold treatment below.
| Low | Typical | High |
|---|---|---|
| $3,200 | $3,200 - $11,900 | $15,500 |
- Full encapsulation: liner on floor and walls, sealed vents (1,200 sq ft)$2,400 - $12,000
- Crawl space dehumidifier, installed$800 - $3,500
This Old House says labor is 50% to 70% of an encapsulation's cost. Applied to the encapsulation line, that is $1,200 - $8,400. The rest is materials.
Dehumidifier size: building code section R408.3 sizes the dehumidification option at 70 pints of moisture removal per day for every 1,000 sq ft of floor. For this floor that is at least 84 pints per day. Check the rating on the unit a quote names.
Some companies fold the dehumidifier into their per-square-foot price. HomeGuide lists dehumidifier installation among the services encapsulation typically includes, so if your quote does the same, the true total can sit lower than the high end shown here.
Estimate only, based on published national cost guides (see sources below). Local labor rates, how tight the crawl space is, and what the crew finds once they are under the house can change the final price. Always get a written, itemized quote.
How we got this
- Floor area of the crawl space: 40 ft × 30 ft = 1,200 sq ft
- Published installed price for full encapsulation, typical band: $2 to $7 per sq ft of floor. The $2 low end is Bob Vila's price for an encapsulation system and $7 is the top of This Old House's range for a basic job. Floor area times that rate: 1,200 sq ft × $2 to $7 per sq ft = $2,400 to $8,400 (Bob Vila, This Old House)
- Small-job minimum: the high end is $1,500 or more, so Bob Vila's starting cost of around $1,500 for small crawl spaces changes nothing. The line stays $2,400 to $8,400. (Bob Vila)
- Lines priced on their own, added to the job: dehumidifier, installed: $800 to $3,500 (HomeGuide, Bob Vila, This Old House)
- Typical cost for this job: $2,400 to $8,400 + $800 to $3,500 = $3,200 to $11,900 (the typical band shown at the top). The High column, $15,500, swaps in the $10 per sq ft top of the published encapsulation range for the encapsulation line. (HomeGuide, This Old House)
The idea behind it: The cost guides this page cites price encapsulation and vapor barriers by the square foot of crawl space floor, so the floor area drives the main line. A dehumidifier, sump pump, drain, mold treatment or permit is quoted as its own installed price, so each one is added on top as a flat amount.
3. Liner you will need
- Floor1,200 sq ft
- Walls (140 ft around, 3 ft up)420 sq ft
- Seam overlap (2 seams at 6 inches)40 sq ft
- Total liner1,660 sq ft
- Rolls at 1,200 sq ft each (HomeGuide's roll size)2
- Liner material at 12 mil ($0.50 - $0.60/sq ft)$830 - $996
- Vent covers, about 8 (Bob Vila: one vent per 150 sq ft is typical; $10 to $22 per vent from This Old House and Bob Vila)$80 - $176
Buying it yourself: This Old House says materials make up 30% to 50% of an encapsulation's cost, and that share covers the liner, insulation and dehumidifier, not the liner alone. Applied to the encapsulation line above, that is $720 - $6,000. This is materials only: no labor, no warranty, and it does not cover mold, rot or standing water that needs fixing first. See Can I encapsulate a crawl space myself? below.
Check the roll label; the width sets how many seams there are.
Liner prices are HomeGuide's materials-only figures by thickness, with This Old House's lower 20 mil price included. They leave out tape, fasteners and labor. Useful for checking the materials line on a quote.
4. Have a quote already? Check it
Set the options above to match what the quote includes, so you are comparing the same job.
Enter the size of your crawl space and what the job includes to see the low, typical and high cost, how much liner the job takes, and how a quote you already have compares with published national rates.
How this is calculated
The base line is priced per square foot of crawl space floor. A floor-only vapor barrier uses $2 to $4 per square foot installed, HomeGuide's figure for a vapor barrier. Bob Vila's FAQ gives the same $2 to $4, but for a full encapsulation system, so it is not used for the vapor barrier rate.
Full encapsulation uses $2 to $10 per square foot. HomeGuide and This Old House put the high end at $10, and Bob Vila's FAQ prices full encapsulation as low as $2. The typical band runs from that $2 low end up to $7 per square foot, This Old House's top figure for a basic job, so a quote at Bob Vila's FAQ rate still counts as typical. When you tick standing water, the typical band runs to $10, since This Old House says crawl spaces with extensive moisture problems reach that price. For a very small crawl space, the typical and high ends stay at $1,500 or more, because Bob Vila says costs start around $1,500 for small crawl spaces.
Each option you tick adds its own range. Where the guides disagree, the calculator uses the lowest low and the highest high, so a fair quote is not flagged just because one guide prices it differently.
| Option | Range used | Where it comes from |
|---|---|---|
| Dehumidifier, installed | $800 - $3,500 | Bob Vila $800 - $1,200; This Old House $800 - $2,000; HomeGuide $1,000 - $3,500 (service table) |
| Sump pump, installed | $650 - $1,800 | Bob Vila |
| Interior drain | $600 - $5,200 | This Old House $600 - $1,800 (full drainage system); Bob Vila $700 - $5,200 (complete interior drain system); HomeGuide $800 - $3,000 |
| Mold treatment | $500 - $6,000 | This Old House $500 - $4,000; Bob Vila $500 - $6,000; HomeGuide $1,500 - $4,000 |
| Old insulation removal | $1 - $2 per sq ft of floor | HomeGuide |
| Permit | $100 - $250 | Bob Vila and This Old House |
| Rigid foam board, walls or subfloor | $1.20 - $3.70 per sq ft | HomeGuide (This Old House's $2.50 - $3.00 falls inside it) |
| Closed-cell spray foam, walls | $1.00 - $5.00 per sq ft | HomeGuide $2.00 - $5.00 (closed-cell, walls); This Old House $1.00 - $3.50 (spray foam, type and location not stated) |
| Blown-in, subfloor | $1.00 - $2.80 per sq ft | HomeGuide |
| Fiberglass or rockwool batts, subfloor | $0.60 - $1.40 per sq ft | HomeGuide $0.90 - $1.40 (subfloor); This Old House $0.60 - $1.10 (fiberglass batt, location not stated) |
Wall insulation is applied to your wall area (the distance around the crawl space times the wall height), and subfloor insulation to the floor area. The low total adds every low figure and the high total adds every high figure.
Worked example
A 40 by 30 foot crawl space with walls about 3 feet high, no standing water. The owner wants full encapsulation with a 12 mil liner and a dehumidifier.
| Line item | Range |
|---|---|
| Full encapsulation, 1,200 sq ft at $2 to $10 | $2,400 - $12,000 |
| Dehumidifier, installed | $800 - $3,500 |
| Low / typical / high | $3,200 / $3,200 - $11,900 / $15,500 |
The low end is $3,200: Bob Vila's $2 per square foot ($2,400 at 1,200 sq ft) plus the dehumidifier's low end. The typical band tops out at $11,900: This Old House's $7 per square foot for a basic job ($8,400) plus the dehumidifier's high end. The same crawl space with a floor vapor barrier only and no dehumidifier comes to $2,400 to $4,800.
The job takes about 1,660 square feet of liner: 1,200 on the floor, 420 up the walls and 40 in joint overlap with 12-foot rolls. That is two 1,200 square foot rolls. At HomeGuide's 12 mil price, the liner material comes to $830 to $996. For the dehumidifier, the R408.3 sizing works out to at least 84 pints per day for 1,200 square feet.
What this estimate leaves out
- Local prices: every rate is a national figure from the cited guides, so labor and materials in your area can differ.
- Repairs found once the space is open: rot, pest damage, structural problems and drainage work beyond the options you tick.
- Moisture causes outside the crawl space, such as gutters and grading, which a liner does not fix.
- Permit fees unless you tick the permit box, and anything a contractor adds that is not on the lines above.
For a final price, get a written quote after the contractor has been in the crawl space.
How much liner the job really takes
Cost guides price encapsulation per square foot of crawl space, but the liner covers more than the floor. In a sealed crawl space it runs up the walls, and building code section R408.3 requires the joints to overlap by 6 inches and be sealed or taped. For the example above, that adds 460 square feet, close to 40 percent more liner than the floor alone.
The calculator works this out from your length, width, wall height and roll width. It then prices the liner by thickness using HomeGuide's materials table, with This Old House's lower 20 mil price included. If a quote lists liner material far below that figure, ask what thickness it is and whether it goes up the walls.
Labor versus materials
This Old House says labor makes up 50% to 70% of an encapsulation's total cost, and materials the other 30% to 50%. That is why two quotes for the same liner can be far apart: most of the price is the crew's time. HomeGuide says tight or obstructed crawl spaces are harder to work in and raise labor costs. It adds that the total depends on local labor prices, the materials included, and whether the space needs repairs or mold remediation.
If there is water or mold down there
Encapsulation keeps ground moisture and outside air out. It does not fix water that is already getting in. HomeGuide says standing water, mold and rot must be dealt with before encapsulation. It says pros recommend a drainage system where the water table is high, water seeps in, or flooding is a risk. If mold is already growing, themold remediation cost estimator prices that part of the job, including a crawl space location.
Before you sign: what to get in writing
- The liner thickness in mils, and whether it covers the walls or only the floor.
- How joints, vents and the access door are sealed.
- Whether a dehumidifier is included, which model, its pints-per-day rating, and where its water drains.
- How any mold, standing water or wood rot will be handled before the liner goes in.
- Who pulls the permit, if your city needs one, and whether it is in the price.
- An itemized list of charges, which Bob Vila and This Old House both suggest asking for.
- What the warranty covers, for both the work and the materials, and for how long.
HomeGuide and This Old House both recommend getting estimates from at least three companies, and HomeGuide says to avoid paying the full amount up front.
Questions people ask
How much does crawl space encapsulation cost?
HomeGuide puts crawl space encapsulation at $3 to $10 per square foot, or $3,000 to $15,000 total. Bob Vila and This Old House both give a range of $1,500 to $15,000 and an average of about $5,500. This Old House puts a basic job at $3 to $7 per square foot and says crawl spaces with extensive moisture problems can reach $10. Bob Vila’s FAQ prices a full encapsulation system lower, at $2 to $4 per square foot, which sets the low end this calculator uses. For a 1,000 square foot crawl space, Bob Vila’s FAQ lists $2,000 to $4,000, HomeGuide lists $3,000 to $10,000, and This Old House lists $3,000 to $7,000.
How much does a crawl space vapor barrier cost?
HomeGuide says a vapor barrier costs about $2 to $4 per square foot installed, and $0.30 to $0.70 per square foot for the material alone. Bob Vila puts the material at $0.50 to $0.70 per square foot, depending on quality and thickness. Bob Vila’s FAQ gives the same $2 to $4 installed figure, but for a full encapsulation system. A vapor barrier on its own covers the floor. Full encapsulation also runs the liner up the walls and seals the vents, and HomeGuide lists a dehumidifier among the services it typically includes, which is why it costs more.
What is the difference between a vapor barrier and full encapsulation?
A vapor barrier is a plastic sheet laid over the dirt floor to keep ground moisture out. Encapsulation seals the whole space: the liner covers the floor and the foundation walls, and the vents to the outside are sealed. Building code section R408.3 covers unvented crawl spaces. It calls for a continuous Class I vapor retarder over the exposed earth, with joints overlapped 6 inches and sealed or taped. The edges must run at least 6 inches up the stem wall and be attached and sealed to the wall or insulation. Your local building department can tell you which code edition applies where you live.
What liner thickness should I get?
HomeGuide prices liner material by thickness at 6, 8, 10, 12 and 20 mil, from $0.30 to $0.35 per square foot at 6 mil up to $0.60 to $0.70 at 20 mil. This Old House prices 20 mil lower, at $0.40 to $0.60, so the calculator uses $0.40 to $0.70 at that thickness. (HomeGuide and This Old House write these thicknesses as millimeters; this calculator uses the same numbers and labels them mil.) HomeGuide says thicker barriers cost more but improve performance and durability. Whatever the thickness, ask that the quote name it in writing, so you can compare bids on the same material.
Does an encapsulated crawl space need a dehumidifier?
It depends on the climate. HomeGuide says an encapsulated crawl space in a humid environment needs one, because humidity can still build from condensation or leaks. Bob Vila says not necessarily: it matters more where humidity is high, and elsewhere the encapsulation alone is often enough. Building code section R408.3 lists dehumidification as one option for an unvented crawl space, sized at 70 pints of moisture removal per day for every 1,000 square feet of floor. Installed, a crawl space dehumidifier runs $800 to $1,200 according to Bob Vila and $800 to $2,000 according to This Old House. HomeGuide says $1,000 to $3,000 in its text and $1,000 to $3,500 in its service table. Bob Vila and This Old House both note that the water it collects needs somewhere to drain, so a sump pump or drain may be needed too.
What adds the most to the price?
Problems that have to be fixed before the liner goes in. HomeGuide says pre-existing mold, rot or standing water must be dealt with first, and puts crawl space repairs at $500 to $8,000. Bob Vila puts repairs at $1,500 to $15,000, depending on the extent of the fix. Mold removal runs $500 to $4,000 according to This Old House, $500 to $6,000 according to Bob Vila, and $1,500 to $4,000 according to HomeGuide. An interior drain costs $800 to $3,000 according to HomeGuide and $700 to $5,200 according to Bob Vila, and This Old House prices a full drainage system at $600 to $1,800. A sump pump runs $650 to $1,800 according to Bob Vila. Access matters too: HomeGuide says tight or obstructed crawl spaces raise labor costs.
Do I need a permit to encapsulate a crawl space?
It depends on your city. Bob Vila says many communities require one, and This Old House says crawl space work usually does. Both put the permit at $100 to $250. Bob Vila says the inspection is typically included in the permit cost, and This Old House says it often is. Ask your contractor whether they pull the permit and whether it is in the quote.
Can I encapsulate a crawl space myself?
The materials are sold at home improvement stores, and the liner section of the calculator shows how much you would need and what it costs. Bob Vila advises against doing it yourself: the space has to be sealed completely or it can end up with worse moisture problems than before, and a DIY job carries no warranty. This Old House says handy homeowners can do it, but that it is usually a job for professionals, who have the training for work such as creating a drainage system and wiring a dehumidifier. Bob Vila says the dehumidifier and sump pump are not DIY-friendly.
Is crawl space encapsulation worth it financially?
HomeGuide says most homeowners recover the cost within 7 to 10 years through lower energy bills, fewer repairs and higher property value, but it does not show how it arrived at that figure. ENERGY STAR says sealing air leaks and adding insulation can provide up to 10% savings on a home’s annual energy bill. That figure is for a whole home’s air sealing and insulation together, not for crawl space encapsulation by itself, and “up to” means it is a ceiling for a well-done whole-home job, not a typical result. Treat both as rough guides, not a promise the job pays for itself, and weigh them against the cost estimate above.
Where these numbers come from
- HomeGuide: Crawl Space Encapsulation Cost (per-sq-ft rate, size table, 7 to 10 year payback, service costs, vapor barrier by thickness and roll size, insulation by type, old insulation removal, dehumidifier, drainage, mold, repairs, cost factors, three estimates; checked Sep 28, 2026)
- Bob Vila: Crawl Space Encapsulation Cost (total range and average, small-job starting cost, per-sq-ft FAQ rate, material price, dehumidifier, sump pump, interior drain, mold, repairs, vent covers and vent spacing, permit, itemized bids, DIY; checked Sep 28, 2026)
- This Old House: Crawl Space Encapsulation Cost (basic and extensive-moisture rates, labor and materials share, 20 mil liner price, vent sealing, insulation by type, dehumidifier, drainage, mold, permit, three estimates, DIY; checked Sep 28, 2026)
- UpCodes: Section R408.3 Unvented Crawl Space, International Residential Code text as adopted in the Texas State Residential Code 2018 (Class I vapor retarder, 6-inch joint overlap, 6 inches up the stem wall, 70 pints per day per 1,000 sq ft dehumidification option; checked Sep 28, 2026)
- US EPA: A Brief Guide to Mold, Moisture and Your Home (recommended indoor relative humidity; checked Sep 28, 2026)
- ENERGY STAR: Seal and Insulate (whole-home energy savings from air sealing and insulation; checked Sep 28, 2026)
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