House Wrap and Moisture Barrier Coverage Calculator
Calculate the total square footage of house wrap or moisture barrier needed for walls or floors, accounting for overlaps, openings, and waste factor.
Formulas Used
Gross Wall Area:
Gross Area = Wall Width × Wall Height
Number of Horizontal Courses:
Effective Course Height = Roll Width − (Horizontal Overlap ÷ 12)
Courses = ⌈Wall Height ÷ Effective Course Height⌉
Total Installed Height:
Total Install Height = Courses × Roll Width
Vertical Seam Adjustment:
Vertical Seams = ⌈Wall Width ÷ Roll Length⌉ − 1
Total Run Width = Wall Width + (Vertical Seams × Vertical Overlap ÷ 12)
Raw Wrap Area (with all overlaps):
Raw Area = Total Install Height × Total Run Width
Adjusted Area:
Adjusted Area = Raw Area − Opening Area
Total Wrap Needed:
Total = Adjusted Area × (1 + Waste % ÷ 100)
Rolls Required:
Rolls = ⌈Total Wrap Needed ÷ (Roll Width × Roll Length)⌉
Assumptions & References
- Standard house wrap rolls are commonly 9 ft × 100 ft (900 sq ft per roll) per manufacturer specs (Tyvek, Typar, etc.).
- A minimum 6-inch horizontal overlap between courses is required per most building codes and manufacturer installation guides.
- A minimum 12-inch vertical seam overlap is standard practice per ICC building code and manufacturer recommendations.
- A 10–15% waste factor is recommended by the National Association of Home Builders (NAHB) for typical installations.
- Window and door rough openings are subtracted from gross area; however, wrap is typically cut and folded into openings — this calculator deducts the full opening area as a conservative estimate.
- This calculator applies to vertical wall applications. Crawl space or under-slab moisture barriers may require different overlap standards.
- Always consult local building codes and manufacturer installation instructions for project-specific requirements.
- Reference: ICC International Residential Code (IRC) Section R703 — Exterior Covering.