Crawl Space Encapsulation Cost & Materials Calculator
Crawl space encapsulation seals the space with a heavy vapor barrier on the floor and walls, then controls moisture with a dehumidifier or conditioned air. HomeGuide puts the cost at $3–$10 per square foot depending on scope.
Enter your crawl space dimensions to see the price range, liner material quantity, and dehumidifier sizing. The calculator also flags drainage, mold, and repair work that may be quoted separately.
Related guides
How this works
This calculator turns your measurements into the price ranges published by HomeGuide (Jan 2026) and Angi (Jul 2026). Encapsulation is priced per square foot of crawl space floor, so we multiply your area by HomeGuide's $3–$10 range (or $2–$4 for a floor barrier only). That range covers the spread from a basic liner and sealing job to a heavy-duty liner with a dehumidifier. Repairs, drainage, and mold work are listed separately because both sources price them separately and they vary the most.
Liner quantity is the floor area plus the wall area (perimeter × wall height). For a floor-only barrier it's the floor plus 6 in up the wall, the minimum in IRC R408.3. We add an allowance for laps and cuts, which you can change. Rolls are counted at 1,200 sq ft each with HomeGuide's per-roll prices by thickness. Dehumidifier sizes come from Angi's size table and, where they apply, the code formulas in NC R409 and IRC R408.3. These are planning figures: a local pro's inspection sets the real scope, and the code your jurisdiction has adopted controls.
Estimates only — independent local providers quote their own pricing. Data last reviewed 2026-10.
Sources
- HomeGuide — Crawl Space Encapsulation Cost (Jan 2026) (third-party estimate)
- HomeGuide — Crawl Space Dehumidifier Cost (Dec 2025) (third-party estimate)
- IRC R408.3 Unvented Crawl Space (UpCodes)
- NC OSFM — Permit Required for Closed Crawl Space
- EPA — A Brief Guide to Mold, Moisture and Your Home
Frequently Asked Questions
How much does it cost to encapsulate a 1,500 sq ft crawl space?
HomeGuide puts it at $4,500–$15,000. Angi's national average for all sizes is $5,500.
How many rolls of vapor barrier do I need?
Floor plus walls plus an allowance, divided by the roll size. A 1,500 sq ft space with 3-ft walls needs about 2,160 sq ft, or two 1,200 sq ft rolls.
What size dehumidifier does a crawl space need?
Angi's table suggests 30–50 pints for spaces up to 1,500 sq ft. Where the IRC dehumidifier option is adopted (Virginia, for example), the code figure is 70 pints/day per 1,000 sq ft. North Carolina requires at least a 15-pint rated unit.
Do I need a permit?
In North Carolina, yes, to close a vented crawl space. Henrico County, VA lists encapsulation as permit work. Elsewhere, ask your building department.
Does encapsulation fix mold?
EPA says the key to mold control is moisture control, and existing mold should be cleaned up and the water problem fixed. Encapsulation addresses moisture; remediation is a separate line item.
Rather skip straight to quotes?
Send the short form — we'll route you to an independent local pro.