Vapor Barrier Calculator
Calculate how many rolls of plastic sheeting or vapor barrier you need for crawl spaces, floors, or walls.
Vapor Barrier Needed
Vapor barrier rolls are calculated based on the total coverage area plus overlap.
Total Area = Length x Width
Area with Overlap = Total Area x 1.10 (for 6-inch overlaps at seams)
Rolls Needed = Area with Overlap / Roll Coverage
Common vapor barrier sizes:
- 6 mil polyethylene: Most common for crawl spaces and under slabs
- 10 mil: Better durability for crawl spaces
- 20 mil: Premium, puncture-resistant
Standard roll sizes:
- 10 ft x 100 ft = 1,000 sq ft
- 12 ft x 100 ft = 1,200 sq ft
- 20 ft x 100 ft = 2,000 sq ft
Tips:
- Allow 6-12 inches overlap at seams
- Run material 6 inches up walls in crawl spaces
- Tape all seams with vapor barrier tape