Vapor Barrier Calculator — m, rolls, cost
How to use this calculator
Select application — crawlspace floor, wall interior, under-slab, or custom area. Choose membrane thickness (0.15-0.5 mm) and roll size. Set overlap (15-30 cm) and waste allowance. Results update instantly.
Seam tape — vapor barrier tape 50 mm wide, ~55 m per roll, for all overlapping seams.
Fasteners — staples for wall applications (~1 per 30 cm along seams), acoustic sealant for perimeter.
Cost — per roll of membrane, tape, staples/sealant. Select currency below.
Saved Calculations
| Time | Application | Area m² | Rolls | Cost |
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How to Calculate Vapor Barrier
Measure the area to cover — crawlspace floor, wall interior, or under-slab. For crawlspaces, add wall run-up height to account for membrane running up foundation walls. Apply seam overlap (15 cm for floors, 30 cm for walls) and waste allowance.
Formulas
Base area = length × width. Crawlspace: total = floor area + perimeter × run-up height. Overlap factor = 1 + (overlap / roll width). Adjusted area = base × overlap factor × (1 + waste%). Rolls = adjusted area / roll coverage.
Membrane Thickness Guide
0.15 mm — standard PE foil for most crawlspaces and under-slab per EN 13984. 0.25 mm — heavy-duty for high-traffic crawlspaces. 0.38 mm — premium, puncture-resistant. 0.50 mm — commercial grade, reinforced per DIN 4108-3.
FAQ
How much overlap? Minimum 15 cm for floor applications, 30 cm for wall seams per DIN 4108-3. Do I tape the seams? Yes — all seams must be taped with approved vapor barrier tape. Do I need sealant? Apply acoustic sealant at all perimeter edges where membrane meets foundation walls, piers, or other penetrations.
