Roofing materials guide
Waste factor is the material you expect to lose to cuts, starter pieces, damaged bundles, and complex roof geometry. It should be reasoned, not guessed.
Roofing squares describe the surface area, but shingles arrive in bundles and must be cut around hips, valleys, walls, penetrations, and changes in plane. Waste factor increases the material order above measured squares. It does not mean the roof is larger than the measurement report.
| Roof shape | Planning range | Why |
|---|---|---|
| Simple gable | 10% | Long runs and fewer cuts. |
| Standard hip | 12–15% | More cuts and hip material. |
| Cut-up roof with valleys | 15%+ | Short runs, valleys, dormers, and transitions. |
These are planning ranges, not promises. Use your measured report, roof geometry, product coverage, and crew experience to choose the final factor.
Waste factor should not silently absorb steep-slope labor, extra tear-off, decking replacement, access, disposal, or flashing repairs. Put those items in their own line items or allowances so the homeowner can understand the proposal and your team can track them.
Calculate the order quantity with the free roofing calculator, then use the estimate template to show the assumption clearly.