SettingsSettings for this calculationUS
The standard allowance most suppliers and estimating guides assume for ordinary work.
The total floor area of the crawlspace to be lined.
Measure the full footprint of the crawlspace floor that will be covered by the vapor barrier liner.
The total perimeter of the crawlspace walls being lined.
Measure around the full inside perimeter of the crawlspace foundation walls.
The height the liner extends up the crawlspace walls.
Typically the liner runs from the floor up to just below the sill plate or to the height specified by the encapsulation design.
Extra liner material to allow for overlaps, seams, and cut waste.
Crawlspaces often have piers, ductwork, and an irregular perimeter, so a higher waste allowance is typical compared to an open floor area.
Liner needed
800.2 sq ft
- Wall area
- 297.5 sq ft
They open the calculator with your figures already in it
Crawlspace Encapsulation Liner Calculator: 800 sq ft — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
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How this was calculated
Formula source(s)
- Total liner area = floor area + wall area (perimeter × wall height); liner needed = total area × (1 + waste allowance), covering both the floor and the crawlspace wall lining in a full encapsulation system
Inputs used
- Crawlspace Floor Area
- 430 sq ft
- Crawlspace Wall Perimeter
- 85 ft
- Crawlspace Wall Height
- 3.5 ft
- Waste Allowance (%)
- 10
Intermediate steps
- Wall area
- 297.5 sq ft
What this calculation does not cover
- Piers, columns and interior footings carry no term in the arithmetic: the total is the floor footprint plus perimeter times wall height, so liner wrapped around a masonry pier or carried up an interior support is extra material this figure does not contain.
- A single wall height is applied around the entire perimeter, so a stepped footing, a sloping site, or a run that drops into a full-height basement wall has to be split and estimated in sections — and the height field caps at 2.5 m (about 8 ft), short of a true basement lift.
- Floor area and perimeter are read as two independent numbers and never reconciled, so nothing objects when the perimeter you enter could not physically enclose the floor area you enter, and a transposed digit in either still returns a plausible-looking total.
- The waste allowance is one multiplier on the combined floor-and-wall total rather than a separate overlap on each surface, it is already folded into the headline number with only the wall area broken out beneath it, and it stops at 20% — below what a crawlspace crowded with ducts, plumbing drops and pier blocks can actually consume.
- The perimeter you enter serves only to generate wall area and is never returned as a linear run, so the seam tape, adhesive and top-of-wall termination that make an encapsulation airtight — quantities that follow seam length rather than area — sit outside this answer.
Estimated cost — your price
This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.
Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.
Sources checked 2026-09-05 · in the site-wide review of 2026-09-06 · v1.0.1
Regulatory standards & verification citations1
- Total liner area = floor area + wall area (perimeter × wall height); liner needed = total area × (1 + waste allowance), covering both the floor and the crawlspace wall lining in a full encapsulation system
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