Crawl Space Encapsulation Cost Calculator
Encapsulation turns a damp, vented crawl space into a sealed, dry part of the house: a heavy liner over the floor and up the walls, the vents closed, the walls insulated and a dehumidifier to keep it dry. Each of those is a separate line on a quote. Enter your crawl space and choices, and this prices every part as a contractor job or DIY.
Your project
Add up the outside walls. A 25 × 40 ft house is 130 ft.
Your results
- Installed encapsulation cost
- $4,594 – $9,172
- Cost per sq ft of crawl space
- $4.59 – $9.17
- Liner needed
- 1,529 sq ft (2 × 10×100 ft rolls)
- Floor + 390 sq ft of wall, +10% for overlaps
- Liner, installed
- $2,294 – $4,587
- Wall insulation
- $780 – $1,365
- 14 sheets of 4×8 foam board
- Dehumidifier
- $1,200 – $2,500
- Seal 8 vents
- $320 – $720
Estimates use typical US material and labor pricing. Confirm quantities against the coverage chart on the bag before you buy.
Gear for this job
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Prices as of Oct 1, 2026, 4:38 AM UTC. Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.com at the time of purchase will apply to the purchase of this product.
How this calculator works
- Liner sq ft = (floor area + perimeter × wall height) × 1.10
- Liner = liner sq ft × $1.25–$4.00 installed by thickness (DIY $0.20–$0.80 material)
- Wall insulation = perimeter × wall height × $2.00–$4.00 (DIY $1.00–$3.00)
- Dehumidifier $1,200–$2,500 · vents $40–$90 each · sump $1,000–$2,500 · cleanup $0.75–$1.50/sq ft
- Total = liner + walls + dehumidifier + vents + sump + cleanup
Crawl space encapsulation cost by size (12 mil liner, rigid foam walls, dehumidifier, 3 ft walls)
| Crawl space | Contractor | DIY | Per sq ft (pro) |
|---|---|---|---|
| 500 sq ft | $3,193 – $6,388 | $1,598 – $2,654 | $6.39 – $12.78 |
| 800 sq ft | $4,031 – $8,047 | $1,825 – $3,065 | $5.04 – $10.06 |
| 1,000 sq ft | $4,594 – $9,172 | $1,975 – $3,341 | $4.59 – $9.17 |
| 1,200 sq ft | $5,136 – $10,258 | $2,116 – $3,605 | $4.28 – $8.55 |
| 1,500 sq ft | $5,897 – $11,775 | $2,315 – $3,968 | $3.93 – $7.85 |
| 2,000 sq ft | $7,156 – $14,296 | $2,639 – $4,568 | $3.58 – $7.15 |
Perimeter assumes a 1.6:1 rectangle and one vent per 125 sq ft. Computed with this calculator.
What you are paying for
The liner is the biggest single item: a reinforced polyethylene sheet over the whole floor, lapped and taped at every seam, wrapped around piers and run up the foundation walls to within a few inches of the sill, where it is fastened with a termination bar. Thicker liners cost more but survive being crawled on; 12 mil is the common middle choice and 20 mil is for crawl spaces that get regular traffic or storage.
Sealing the space changes how it has to be dried. Once the vents are closed, the crawl space needs either a dedicated dehumidifier or a small supply of conditioned air from the HVAC system, and building codes treat a sealed crawl space as part of the conditioned house — which is why the foundation walls, not the floor above, get the insulation.
Water comes first. If water stands on the floor after rain, fix the grading and gutters and add a drain or sump before sealing, or the liner simply traps the problem.
Is encapsulation worth it?
In humid climates, a vented crawl space brings damp summer air under the house, where it condenses on cool ducts and framing. Encapsulation keeps the framing dry, stops musty air reaching the living space, and puts ducts that run through the crawl space inside the conditioned envelope. The energy saving is real but usually modest; most owners do it for moisture, mold and comfort.
Published 2026 cost guides (Angi, HomeGuide, Forbes Home) put typical full encapsulation at roughly $5,000–$15,000, or about $3–$9 per square foot, with basic liner-only jobs below that and jobs with drainage, mold remediation or structural repair above it. This calculator prices each part so you can see which of those lines is in your quote.
Keep going
- Liner only: vapor barrier square footage and cost
Frequently asked questions
How much does crawl space encapsulation cost?
In this calculator a 1,000 sq ft crawl space with 3 ft walls, a 12 mil liner, rigid foam on the walls, a dehumidifier and 8 sealed vents costs about $4,600–$9,200 with a contractor, or $4.60–$9.20 per sq ft. Add $1,000–$2,500 for a sump pump if water pools.
How much does it cost to encapsulate a 1,000 sq ft crawl space yourself?
About $2,000–$3,300 for the same job DIY: roughly 1,530 sq ft of 12 mil liner, seam tape and fasteners, foam board for 390 sq ft of wall, a crawl space dehumidifier and vent covers. The dehumidifier is the largest single DIY cost.
What thickness of vapor barrier do I need for encapsulation?
Code minimum for a vented crawl space is 6 mil, but encapsulation liners are usually 10–20 mil reinforced polyethylene: 12 mil is the common choice, 20 mil if you store things down there or crawl through often.
Do I need a dehumidifier after encapsulating?
A sealed crawl space needs a way to remove moisture — either a dehumidifier sized for the space or a small conditioned-air supply from your HVAC system, as the building code allows. Without either, humidity can build up under the liner.
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Installed encapsulation cost
$4,594 – $9,172