How the roof math works
Roofers price by the square — 100 square feet of roof surface. A sloped roof has more surface than the footprint below it, so we multiply the footprint (plus overhang) by the pitch factor, √(1 + (rise/12)²). A 6/12 roof is about 1.118× the flat area; a 12/12 roof is about 1.414×.
Where the price comes from
The cost per square foot is the 2025 Cost vs. Value average job cost for your region divided by the report’s 3,000-sq-ft model roof. That model includes tear-off to bare sheathing, new underlayment, drip edge, flashing and two skylights, so it is a full replacement — not a re-roof over old shingles.
- Asphalt: Tear off to bare sheathing and install 30 squares (3,000 sq ft) of 235-lb fiberglass asphalt shingles with new underlayment, drip edge and flashing; hip roof with two skylights.
- Metal: Tear off to bare sheathing and install 3,000 sq ft of prefinished standing-seam metal roofing with ice barrier, synthetic underlayment and matching trim; hip roof with two skylights.
What moves your quote up or down
- Steep or cut-up roofs (valleys, dormers) take more labor than a simple hip roof.
- Rotten sheathing found during tear-off is usually priced extra per sheet.
- Removing more than one old layer adds disposal cost.
- Permits and local labor rates differ even inside one region.
Frequently asked questions
How many squares is my roof?
Roof area ÷ 100. A 1,800 sq ft footprint with a 6/12 pitch and 1-ft overhang is roughly 21–23 squares.
Is metal worth the extra cost?
In the 2025 report the metal roof averaged about 1.6× the asphalt job nationally. Metal lasts longer, so compare cost per year of life, not just the upfront price.
Does this include gutters?
No. The model project covers roofing, underlayment, drip edge and flashing only.
Sources
Last reviewed 2026-10-14. Estimates only — get written quotes from licensed local contractors before you decide.