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Crawl space encapsulation calculator

Measure the crawl space, enter the rate from your quote, and see what the liner line should cover.

A crawl space encapsulation calculator turns your crawl space size into the liner area a contractor should be pricing: the floor, the stem walls, 6 inches up each wall and the seam laps the code asks for.

Type the per-square-foot rate from your own written quote and it gives the liner total. It holds no prices of its own, because we have no sourced price data to give.

Crawl space encapsulation calculator

Measure the crawl space, enter the rate from your quote, and see what the liner line should cover.

0 if the quote covers the floor only.

From a written quote. No default: we hold no price data.

Dehumidifier, sump, insulation. Optional.

— Liner price at your rate
— Floor and perimeter
— Liner area
— Priced separately

What this assumed —

Not a quote. Liner area only; your rates, not ours.

What the liner line should cover

An encapsulation liner covers more than the floor. For an unvented crawl space, the IRC asks for a continuous Class I vapor retarder with joints lapped 6 inches and sealed, and edges run at least 6 inches up the stem wall and sealed to it.

Many systems run the liner the full height of the wall. This tool adds both, plus 10% for laps and the waste around piers.

Encapsulation is not only plastic. A sealed crawl space also needs a conditioning method: supply air, exhaust fan or a dehumidifier. If a quote seals the vents with no conditioning method, ask why. See crawl space repair for vented against sealed designs.

Use the area to compare bids. Two quotes that price different square footage for the same crawl space are not pricing the same job. Ask each firm what area they measured.

Before you sign an encapsulation quote

  • Fix standing water first

    A liner over a wet floor traps the problem. Drainage and grading come first; see drainage and grading.

  • Ask for the liner thickness and wall height

    Both change the price and the result. Get them in writing.

  • Ask how the space will be conditioned

    Dehumidifier, supply air or exhaust. Size a dehumidifier with the crawl space dehumidifier size calculator.

  • Check wood and structure

    Rotted sills or joists are repaired before they are sealed in. The crawl moisture check helps you read the space.

Questions this calculator answers

How much liner does a crawl space encapsulation need?
More than the floor area. Add the stem walls, at least 6 inches up every wall, and 6 inch laps at each seam. For a 40 by 30 ft crawl space with 2 ft walls, this tool gives about 1,705 sq ft of liner.
Why does the calculator not show a price?
Because we hold no sourced, dated price data for encapsulation. Type the rate from your own written quote and it does the arithmetic. A national average would not describe your crawl space anyway.
Is a vapor barrier the same as encapsulation?
No. A vapor barrier is a ground cover, often used in a vented crawl space. Encapsulation seals the space and adds a conditioning method. The vapor barrier calculator covers the ground-cover case.
Do I need a dehumidifier after encapsulation?
A sealed crawl space needs one of the conditioning methods the code lists. A dehumidifier is one of them. Others use supply air from the house or an exhaust fan.
Should I encapsulate if water stands in the crawl space?
Not first. Find where the water comes from and fix drainage. Sealing a wet crawl space hides the water rather than removing it.

Sources and methodology

Figures dated 26 October 2026. Last reviewed .

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