Waste Factor

Definition

Waste factor is the percentage of extra material added to a roofing material order to account for cuts, overlaps, damaged pieces, and installation mistakes. Standard simple gable roofs use a 10% waste factor. Complex roofs with multiple valleys, hips, dormers, and penetrations need 15-20%. Steep roofs also require more waste because of harder cuts and more frequent replacements of damaged pieces. Always order with waste factor included — running short mid-job costs far more than the extra bundles.