Crawl Space Encapsulation Calculator

Crawl space encapsulation costs $1,500 to $15,000 installed, with most homeowners paying $3,000 to $7,000. A 1,000 sq ft crawl space fully encapsulated (vapor barrier + sealed vents + dehumidifier) runs about $5,000 to $7,000 installed, or roughly $3.00 to $10 per sq ft of floor. Pick a scope below; the calculator handles liner area, dehumidifier, and drainage add-ons.

Estimated total—

Your crawl space

Floor length Floor width

Unit

feetmeters

Wall height (ft)

Scope

Price assumptions

Installed ($/sq ft of floor) DIY liner ($/sq ft, 12-mil) Dehumidifier ($) Drainage / sump ($)

Defaults & assumptions

Defaults: a 1,000 sq ft crawl space (typical 3-bedroom home), 3 ft wall height, full encapsulation, 12-mil liner, US national average rates. Picking a scope prefills the installed $/sqft and the dehumidifier / drainage add-on counts. Wall height can usually be left at 3 ft unless you have a tall (4+ ft) crawl space.

Enter your crawl space dimensions above to see results.

Crawl space encapsulation cost per square foot

Crawl space encapsulation has two pricing surfaces. The installed price is quoted per sq ft of floor footprint — that’s how contractors measure the job — and bundles the liner, sealed vents, insulation, and a sump pump if drainage is included. The DIY material price is per sq ft of liner, which is the floor plus the walls up to the sill plate, plus roughly 10 percent for waste and overlaps. A 20-mil reinforced liner is the standard — $0.30 to $0.50 per sq ft material per liner sq ft — with 6-mil (cheap, prone to tears) and 12-mil (mid-grade) below it. Above the liner, a dehumidifier is the most common add-on ($1,200 to $1,800 for a crawl-space-rated unit) and interior drainage with a sump pump runs $1,000 to $2,500 if your crawl space collects water.

Typical crawl space encapsulation cost (US averages)
Floor area	Scope	Materials only (DIY)	Professionally installed
500 sq ft	Vapor barrier only	$200 to $400	$1,000 to $2,500
1,000 sq ft	Full encapsulation	$400 to $800	$3,000 to $7,000
1,500 sq ft	Full encapsulation	$600 to $1,200	$4,500 to $10,500
2,000 sq ft	Full + dehumidifier + drain	$1,000 to $2,000	$10,000 to $15,000

How the calculator works

Perimeter is 2×(length + width) when both are given, else 4×√floor area (square assumption). Wall area = perimeter × wall height (default 3 ft, the typical residential crawl space height). Liner area = (floor + wall area) × 1.10 — a 10% allowance covers waste and the standard 6″ overlap up the wall. Installed total = floor × your installed $/sqft + flat add-ons for dehumidifier and drainage. DIY materials = liner area × your chosen thickness rate (6/12/20 mil). Add a concrete slab or french drain project to the same property? Use those calculators for the separate costs. Price ranges reflect published US averages from national cost guides (Angi, HomeGuide, HomeAdvisor, This Old House, 2026).

Crawl space encapsulation FAQ

How much does crawl space encapsulation cost?

Crawl space encapsulation costs $1,500 to $15,000 installed, with most homeowners paying $3,000 to $7,000. A 1,000 sq ft crawl space fully encapsulated runs $3,000 to $7,000 installed, or roughly $3.00 to $10 per sq ft of floor footprint. A vapor barrier only is the cheapest option at $1,000 to $2,500; adding a dehumidifier and drainage can push costs above $10,000.

Is crawl space encapsulation worth it?

Yes, in most cases. Encapsulation reduces moisture, mold, and pests, and typically pays back through lower HVAC bills and avoided structural repairs. It is most worthwhile in humid climates and homes with musty smells, sagging floors, or visible moisture. A dehumidifier alone can be enough when moisture is mild.

What is a vapor barrier for a crawl space?

A vapor barrier is a thick polyethylene sheet (typically 12 to 20 mil reinforced) laid over the crawl space floor and run up the foundation walls to the sill plate. 20 mil is the modern standard and resists tearing during installation and future use. A bare 6 mil vapor barrier is the cheapest option but tears easily and rarely lasts more than a few years.

Do I need a dehumidifier in my crawl space?

A dehumidifier is recommended after encapsulation in most US climates, especially humid ones (zones 1 through 4). A crawl-space-rated dehumidifier ($1,200 to $1,800) keeps relative humidity below 60% and prevents mold even when the vapor barrier alone cannot fully stop moisture. In dry climates (high desert, mountain west) it may be unnecessary.