How the calculator works
Most online roof calculators ask you to estimate your roof size — and most homeowners get it wrong by 20-40%, which means the estimate is meaningless. RoofTap pulls satellite imagery for your specific address, traces every facet, calculates the actual roof surface area (not just floor sqft × multiplier), and applies regional pricing for the materials you select.
What we factor in
Our calculation includes:
- Actual roof surface area in sqft (not floor sqft)
- Pitch — steeper pitches require more labor and have higher waste factors
- Number of facets — more facets = more cuts, ridges, valleys, and labor
- Number of penetrations — chimneys, skylights, vent stacks each add labor
- Regional material and labor cost from current pricing data
- Material-specific waste factors (asphalt 10-15%, metal 15-20%, tile 20-30%)
- Tear-off, disposal, underlayment, and standard accessories
What's NOT in the estimate (and where to ask)
These vary too much for an automated estimate; bring them up with the contractor:
- Decking replacement — depends on what they find when shingles come off
- Code upgrades — depends on local code and what's already installed
- Skylight or chimney work
- Ventilation upgrades
- Premium underlayments (synthetic vs. felt) or accessories