Crawl Space Encapsulation Cost Calculator

How to use the crawl space encapsulation cost calculator

1. Measure the footprint. Enter length and width, or switch to area + perimeter for an L-shape or a house with additions.
2. Enter the wall height from the dirt to the top of the foundation wall; average a few spots.
3. Choose floor-only or full encapsulation. Floor-only still laps 6 in up the walls; full encapsulation lines the walls too.
4. Count the vents that will be sealed, and enter any area with visible mold.
5. Pick the extras: dehumidifier, wall insulation, drain and pump, insulation removal, permit.

The headline figure is the midpoint of the low and high totals, with every line shown below it. Under the results, a table shows what each published source says for the whole job and a box lets you check your own quote against the range.

What crawl space encapsulation costs

HomeGuide puts a typical job at $3 to $10 per square foot of crawl space, or $3,000 to $15,000 in total. Angi gives an average of $5,500, with $2 to $4 per square foot for a basic job and $3 to $10 when cleaning, repairs and extras are added. Both are national figures; local labor rates and the condition of the space move the price most.

Prices from HomeGuide and Angi. Labor is the biggest share. Angi estimates it at 50% to 70% of the total, which is why a tight, cluttered crawl space with low clearance costs more than an open one of the same size.

How much vapor barrier you need

The International Residential Code sets the minimum for an unvented crawl space in section R408.3. Exposed earth must be covered with a continuous Class I vapor retarder. Joints must overlap by 6 in and be sealed or taped, and the edges must run at least 6 in up the stem wall and be attached and sealed to the wall or its insulation. The calculator builds in both 6-inch figures: each strip of liner loses half a foot to the overlap with the next one, and a floor-only job still adds a 6 in strip around the perimeter.

A 40 × 30 ft crawl space with 3 ft walls has 1,200 sq ft of floor and 140 ft of wall, or 420 sq ft of wall. Lined floor and walls is 1,620 sq ft. With 12 ft rolls the overlaps add about 4%, and a 10% allowance for piers, cuts and wrinkles brings the purchase to about 1,860 sq ft, or two 1,200 sq ft rolls. Seam tape comes to roughly 245 ft: about 104 ft of seams across the floor plus 140 ft where the liner meets the wall.

Thickness is the main material choice. HomeGuide lists 6 mil liner at about $0.30 to $0.35 per sq ft and 20 mil at $0.60 to $0.70. Thicker liners cost more but stand up better when someone has to crawl over them to reach plumbing or ducts.

How the estimate compares with other sources

Each line is priced from published national ranges, and the headline is the midpoint of the low and high totals. For a whole job, HomeGuide gives $3,000 to $15,000 and Angi $5,000 to $15,000 with a $5,500 average (both read on Oct 27, 2026). The default 1,200 sq ft crawl space with a 12 mil liner, wall coverage and a dehumidifier has a $6,285 midpoint, a little above Angi’s average, which covers jobs of every size and scope. Prices vary by region, access height and how wet the space is.

Dehumidifier or conditioned air?

Sealing the vents takes away the outside air that used to dry, or wet, the space, so the code requires one way of controlling humidity. R408.3 allows continuously running exhaust ventilation or conditioned supply air at 1 cubic foot per minute for every 50 sq ft of floor, each with an air path back to the house and insulated perimeter walls. It also allows dehumidification sized at 70 pints of moisture removal per day for every 1,000 sq ft of floor.

For the 1,200 sq ft example that means a dehumidifier rated for at least 84 pints per day, or about 24 cfm of supply or exhaust air. Viridiant’s guide to the Virginia code adds that a crawl space dehumidifier should not need manual emptying.

Insulating the walls instead of the floor

In a vented crawl space, insulation goes between the floor joists. Once the space is sealed and brought inside the home’s envelope, the walls are insulated instead, and old insulation in the floor above is sometimes taken out, which is why the calculator offers that line. Viridiant’s summary of the 2021 Virginia code lists crawl space wall insulation of R-5 continuous or R-13 cavity in climate zone 3, R-10 continuous or R-13 cavity in zone 4, and R-15 continuous or R-19 cavity in zone 5. The insulation must reach from the floor down to finished grade and then at least another 2 ft.

Where termites are a risk, the code also keeps a 1 to 2 in inspection gap below the sill plate free of insulation. Foam board and closed-cell spray foam are the common choices for walls; the spray foam calculator converts the wall area and thickness into board feet and kits if you are pricing it yourself.

Before you sign a contract

• Fix water first. Standing water, a negative grade outside or a missing gutter will defeat any liner. An interior drain is a second line of defense; outside, the French drain gravel calculator sizes a perimeter drain.
• Ask what thickness and what tape. Two quotes for “encapsulation” can mean very different materials. Get the liner thickness, how far it runs up the wall, and how seams and piers are sealed in writing.
• Check radon. Viridiant notes that crawl spaces relying on passive sub-membrane radon venting need an approved mechanical ventilation system before they can be unvented.

Sources & assumptions

How this calculator gets its numbers. Full method: our methodology.

• All prices are national estimates that vary by region, house and crawl space condition, taken from HomeGuide (January 2026) and Angi (July 2026). Get written quotes before you commit.
• Vapor barrier installed at $2–$4 per sq ft is applied to the floor area. Wall foam is priced on the wall area (perimeter × wall height). Mold remediation is priced on the area you enter, capped at the floor area.
• Liner to buy = (floor + walls) × roll width ÷ (roll width − 6 in) × (1 + extra %). The 6 in seam overlap and the 6 in minimum lap up the wall are IRC R408.3 requirements; the 10% default extra for piers and cuts is our allowance.
• Seam tape = floor area ÷ (roll width − 6 in), a conservative seam length, plus the wall perimeter. Dehumidifier size = 70 pints per day per 1,000 sq ft (IRC R408.3).
• The DIY figure covers liner, vent covers and an optional dehumidifier only. It leaves out tape, fasteners, wall insulation, drainage and repairs.

Sources

1. HomeGuide, How much does crawl space encapsulation cost?. $3–$10 per sq ft overall; inspection $100–$250; vapor barrier $2–$4 per sq ft installed and $0.30–$0.70 per sq ft by thickness (6–20 mil, 1,200 sq ft rolls); dehumidifier $1,000–$3,000 installed; wall spray foam $2–$5 and foam board $1.20–$3.70 per sq ft; drain $800–$3,000; old insulation removal $1–$2 and mold remediation $15–$30 per sq ft.
2. Angi, How Much Does Crawl Space Encapsulation Cost?. $5,500 average, $2–$4 per sq ft basic and $3–$10 extensive; vent covers $15–$22 each DIY or $40–$50 installed; permits $50–$250; labor 50–70% of the total.
3. UpCodes, R408.3 Unvented Crawl Space (International Residential Code). Continuous Class I vapor retarder, joints overlapped 6 in and sealed or taped, edges at least 6 in up the stem wall; exhaust or supply air at 1 cfm per 50 sq ft, or dehumidification of 70 pints/day per 1,000 sq ft.
4. Viridiant, Unvented Crawl Spaces (2021 Virginia Residential Code guide). Crawl space wall R-values by climate zone, termite inspection gap, R-5 access doors, and advice that dehumidifiers drain without manual emptying.

Last reviewed October 29, 2026. Installed prices vary by region, contractor and job conditions; a written local bid wins.