Enter footprint length, width, and roof pitch — get the actual roof area (footprint × pitch multiplier), waste-adjusted squares to order, and the labor tier that pitch pushes you into. Bid the shingles, and price the risk.
Free PDF: pitch multiplier chart for all common roof slopes, waste factor lookup by roof complexity, shingle-per-square counts for 3-tab / architectural / premium, underlayment + ice-water shield requirements by climate zone, and a 12-item scope checklist to include on every tear-off + reroof quote.
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Two things kill a roofing bid faster than anything else: ordering short on shingles (job stops, second delivery fee, wasted crew day) and underpricing labor on a steep pitch (crew slows to 40% speed, you eat the difference for the rest of the project). Both come from math that skipped the pitch multiplier or the waste factor.
The footprint of the house is not the roof area. A 40×30 ranch with a 6/12 pitch has 1,341 sq ft of roof, not 1,200. On a 12/12, that jumps to 1,697. Miss this and you're 12–40% short on material with no way to recover margin.
| Pitch | Labor + safety impact |
|---|---|
| 3/12 – 6/12 | Walkable. Standard install pace. No roof jacks required. Most residential ranches and hip roofs. |
| 7/12 – 8/12 | Steep-ish. Toe boards for footing above eave. Slower install pace (~15% labor premium). Common on newer builds with steeper aesthetics. |
| 9/12 – 10/12 | Steep. Roof jacks required per OSHA. Boots + fall arrest. 25–40% labor premium. Cut waste jumps to 20%+. |
| 11/12 and above | Very steep. Full harness + scaffold or roof brackets. 50–100% labor premium. Often better subcontracted to steep-slope specialist crew than absorbed by generalist team. |
Using footprint sq ft as roof sq ft. A 1,500 sq ft footprint at 6/12 pitch = 1,677 sq ft of roof. At 10/12 = 1,953. If you quote 15 squares because "the house is 1,500 sq ft" you're 5 squares short on a 10/12 — that's a full extra day of unbudgeted material handling plus a delivery fee.
Ignoring waste on cut-up roofs. A simple gable roof wastes ~10%. Add two dormers and a valley and it's 18–22%. Add a hip on all four sides with cricket flashings and you're at 25%+. Standard 15% works for a plain hip-or-gable rectangle; anything with cuts costs more.
Not pricing the pitch premium. A crew that installs 4 squares/day on a 6/12 does 2.5 squares/day on a 10/12. Same crew, same skill, half the material moved. If your labor bid was based on 6/12 pace and you're actually installing 10/12, you eat 40% of your labor budget per day for the length of the job.
Materials: squares of shingles (rounded up), underlayment (1 roll per ~4 squares), ice-water shield (eaves + valleys per local code), starter strip (~2 bundles per 40 lineal ft of eave), ridge cap (~1.5 bundles per 100 lineal ft ridge), nails (~2 lbs per square), flashing (step + counter + drip edge). Plus dumpster fee for tear-off.
Labor: price at the pitch premium for the actual roof, not the pitch you wish it was. If bidding a 10/12, quote 25–40% higher labor than 6/12 base rate. Include setup + safety equipment as a separate line — never bury it in "labor" where the customer can negotiate it away.
Contingency: tear-off often uncovers rotten decking. Standard clause: "Deck replacement priced separately at $[X]/sheet plus $[Y] labor per sheet, discovered during tear-off, approved before install." Protects you when the guy who installed the original in 1998 didn't ice-shield the eave.
Bid tear-offs and reroofs from a real price book, protect yourself with the deck-replacement contingency clause every roofer eventually needs, and hand every customer a written scope that stops "you said you'd do X" disputes before they start.