Measure in squares, then add waste
Roofers price by the square: 100 square feet of roof surface. Measure each plane (or use aerial measurements), add them up and divide by 100. A 2,600 sq ft roof is 26 squares.
You'll tear off and underlay the true area, but you'll buy more shingles than that. Cuts at hips, valleys and rakes waste material. A simple gable roof might need around 10% extra; a cut-up roof with many valleys and dormers can need 15% or more. Show the waste in the line ("29 squares incl. 11% waste") so the homeowner understands why the shingle count is higher than the roof size.
Pitch matters too. Steep roofs are slower and need more safety gear, so many roofers add a per-square charge above a certain pitch.
Line items that belong on a roof estimate
- Tear-off per square and per layer. A second layer of old shingles roughly doubles the work, so say how many layers you priced.
- Shingles with the product line and color, installed per square.
- Underlayment and ice and water shield at eaves, valleys and penetrations, if your area calls for it.
- Flashing: step, chimney, pipe boots, drip edge.
- Ventilation: ridge vent or box vents.
- Disposal: dumpster, haul-off, nail sweep.
- Permit, if your city requires one for a re-roof.
Allowances for what you can't see
The decking under the shingles is the classic unknown. You won't know how much is rotten until the old roof is off. Don't guess and bury it in the total: put in an allowance with a unit price ("up to 8 sheets at $95") and say in the notes that the final bill reflects the sheets actually replaced.
That protects both of you. The homeowner sees the worst case up front; you don't eat the cost of hidden rot. Do the same for fascia boards, rafter repair, or anything else hidden.
Exclusions, validity and deposits
Write down what the price doesn't cover: gutters, skylights, chimney masonry, interior ceiling repair, solar panel removal and reinstall. These are the items homeowners assume are included.
Shingle prices change with the season and the supplier, so give the estimate an expiry date. Thirty days is common; after storm season, when supply is tight, shorter is safer.
Deposit rules vary by state. Some cap how much a contractor can take before work starts (California limits most home improvement down payments to $1,000 or 10%, whichever is less), so check your state before printing your terms. Once the job is done, the matching roofing invoice can be made from this estimate without retyping it.
Repairs vs full replacement
Not every roof estimate is a tear-off. For leak repairs, price the visible fix (replace 30 sq ft of shingles, reseal a pipe boot, new step flashing at the chimney) as a fixed line, and add an hourly allowance for tracing the leak if it isn't obvious. Say clearly that a repair doesn't guarantee the rest of the roof.
When the roof is near the end of its life, giving the homeowner both options on one page, repair now or replace, helps them decide and shows you're not just chasing the bigger job.
Last checked October 23, 2026.