Floor and slab barrier estimator

Vapor Barrier Calculator

Estimate floor or slab vapor barrier rolls, overlap waste, wall upturn allowance, seam tape, and rough material cost from area, perimeter, roll coverage, and tape length.

Units

Floor or slab area (ft²)Perimeter for upturn (ft)Wall upturn allowance (ft)Overlap allowance (%)Waste / cuts (%)Coverage per roll (ft²)Tape allowance per barrier roll (ft)Tape roll length (ft)Cost per barrier roll ($)Cost per tape roll ($)

Barrier rolls

Barrier area

Tape rolls

Rough cost

Moisture control is assembly specific

This calculator estimates rolls and seam tape only. Slab moisture, radon rules, crawlspace ventilation, insulation location, perm rating, puncture protection, tape compatibility, and local code decide the real vapor-control assembly.

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Concrete Slab Cost Calculator

Estimate slab material and labor before adding vapor barrier line items.

Flooring Calculator

Estimate finished flooring after the moisture-control layer is planned.

House Wrap Calculator

Estimate exterior barrier rolls with a similar coverage method.

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Vapor barrier formula

Base barrier area = floor area + perimeter × wall upturn

Order area = base area × (1 + overlap % + waste %)

Barrier rolls = order area ÷ roll coverage

Tape rolls = rounded barrier rolls × tape allowance ÷ tape roll length

Sample takeoff

A 600 ft² slab with 100 ft perimeter, 0.5 ft wall upturn, 10% overlap, 5% waste, and 1,000 ft² rolls needs one roll and one seam-tape roll.A 56 m² slab with 30 m perimeter, 0.15 m wall upturn, 10% overlap, 5% waste, and 93 m² rolls needs one roll and one seam-tape roll.

Vapor Barrier Calculator FAQ

How do I calculate vapor barrier rolls?+

Add floor area and any wall upturn allowance, add overlap and waste, then divide by roll coverage. Round rolls and tape up for ordering.Add floor area and any wall upturn allowance, add overlap and waste, then divide by roll coverage. Round rolls and tape up for ordering.

Should I include wall upturn?+

Include it if the slab, crawlspace, or flooring assembly calls for the barrier to turn up at walls or piers. Use the plan or product instructions.Include it if the slab, crawlspace, or flooring assembly calls for the barrier to turn up at walls or piers. Use the plan or product instructions.

Does this decide the perm rating?+

No. Perm rating, thickness, puncture resistance, radon details, and tape compatibility must come from code, product data, and the assembly design.No. Perm rating, thickness, puncture resistance, radon details, and tape compatibility must come from code, product data, and the assembly design.