Roofing Underlayment Calculator
Estimate felt or synthetic underlayment rolls for roof areas with single or double layers. Add waste for overlaps, valleys, and starter courses when planning orders.
Inputs
Tip: Many installs use double coverage at eaves or in valleys. Add extra waste for complex roof geometry.
Results
Rolls needed
6
Adjusted coverage: 2,200 sq ft
Assumptions
- Coverage varies by overlaps, fastener rows, and starter courses.
- Waste factor accounts for offcuts, valleys, and detailing.
- Roll coverage assumes full usable area; check product specs.
Next Steps
- ✓ Verify roof area with the roofing squares calculator
- ✓ Review best practices in the roofing calculators guide
Example
A 2000 sq ft roof with 1 layer(s) and 10% waste needs about 6 rolls of underlayment using the selected coverage.
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New to Roofing Calculations?
Start with our comprehensive Roofing Calculator Guide to understand roofing squares, bundles, pitch multipliers, and material estimates before ordering.