How to read a roofing estimate (2026):
line by line, with a Seattle example
WHAT SHOULD A ROOFING ESTIMATE INCLUDE?
A roofing estimate should list the roof size in squares, tear-off, underlayment, shingles or other material, flashing and drip edge, ventilation, a price for replacing rotten decking, permits, sales tax and the warranty. HomeGuide puts a typical roof replacement at $400 to $900 per square (100 sq ft), installed. In Washington, sales tax applies to the whole contract, labor included.
A roofing estimate, line by line
| Line | What it means | Typical price (HomeGuide, U.S.) |
|---|---|---|
| Roof size (squares) | 1 square = 100 sq ft of roof surface. Every other line depends on it. | — |
| Tear-off and disposal | Removing the old roofing down to the decking | $100–$300 per square |
| Materials | Shingles or other roofing, plus accessories | $100–$250 per square |
| Labor | Installing the new roof | $200–$350 per square |
| Underlayment | The layer between the decking and the shingles | $0.10–$0.80 per sq ft |
| Drip edge | Metal edge along the eaves and rakes | $1.50–$3 per linear ft |
| Vents | Roof ventilation | $200–$700 |
| Decking | Replacing rotten sheathing found after tear-off | $2–$5 per sq ft |
| Permit | Building permit, if your city requires one | $100–$500 |
Angi adds that a contractor's extended workmanship warranty can cost $500 to $2,000. A warranty line should say who backs it: the shingle manufacturer, the roofer, or both.
Example: an 18-square roof in Seattle
Angi puts the average Seattle roof at about 1,800 sq ft, or 18 squares. Here's what HomeGuide's rates give for that roof. The drip edge length is our assumption for illustration.
| Line | Calculation | Range |
|---|---|---|
| Tear-off and disposal | 18 squares × $100–$300 | $1,800–$5,400 |
| Materials | 18 squares × $100–$250 | $1,800–$4,500 |
| Labor | 18 squares × $200–$350 | $3,600–$6,300 |
| Underlayment | 1,800 sq ft × $0.10–$0.80 | $180–$1,440 |
| Drip edge | 180 ft × $1.50–$3 (assumed length) | $270–$540 |
| Vents | Flat range | $200–$700 |
| Subtotal | $7,850–$18,880 | |
| Seattle sales tax, 10.55% | On the whole contract | $828–$1,992 |
| Total | $8,678–$20,872 |
Decking is the line most likely to change after work starts, because rot is often hidden until the old roof comes off. A sheet of decking is 4 × 8 ft, or 32 sq ft, so HomeGuide's $2–$5 per sq ft works out to about $64–$160 per sheet. Ask for a written price per sheet before you sign. To estimate your own roof size, use our roof replacement cost calculator.
How to compare roofing bids
- Get at least 3 written bids. Washington's Department of Labor & Industries (L&I) recommends this and says to "compare them carefully."
- Check the number of squares. If one bid lists far more or fewer squares than the others, ask how the roof was measured.
- Check the materials by name. The shingle line, underlayment type and flashing should be the same on every bid you compare.
- Check what's excluded. Decking, permits, gutters, skylights and chimney flashing are common exclusions.
- Check the warranty. Ask how many years the workmanship warranty lasts and whether it's in writing.
- Check that tax is shown. A bid without sales tax isn't comparable with one that includes it.
Washington rules that affect your estimate
- Sales tax on labor: Washington contractors collect retail sales tax "on the gross contract price," labor included (Department of Revenue). Seattle's rate is 10.55% since January 1, 2026. Rates for other cities are in our sales tax on home repairs guide.
- Permit: SDCI says a permit is not required for re-roofing one- and two-family homes and townhouses if no changes are made to the building envelope other than adding or replacing insulation. Other cities have their own rules. See our roof replacement cost in Seattle guide for details.
- Disclosure statement: For jobs of $1,000 or more on a home, the contractor must give you a written disclosure statement before work starts (RCW 18.27.114).
- License, bond and insurance: L&I's Verify a Contractor tool shows whether a roofer has an active license, bond and insurance, plus past violations.
- Written contract: L&I says to get a written contract and make sure you understand the terms, and to consider a performance bond for larger projects.
Frequently asked questions
What should a roofing estimate include?
The roof size in squares, tear-off, materials, labor, underlayment, flashing and drip edge, ventilation, a price for replacing rotten decking, permits, sales tax and the warranty. HomeGuide puts tear-off, materials and labor together at $400 to $900 per square.
What is a square on a roofing estimate?
A square is 100 square feet of roof surface. An 1,800 sq ft roof is 18 squares.
Why are my roofing bids so different?
Bids often differ in the number of squares, the materials, what's excluded (such as decking or permits) and the warranty. Line them up item by item before comparing totals.
Is sales tax charged on roofing labor in Washington?
Yes. The Department of Revenue says contractors working for homeowners collect retail sales tax on the gross contract price, which includes labor. Seattle's rate is 10.55%.
How much does replacing roof decking cost?
HomeGuide lists $2 to $5 per square foot, or about $64 to $160 per 4 × 8 ft sheet by our math. Ask for the price per sheet in writing before work starts.
Need a repair instead of a new roof? See roof repair cost by type of repair, or roof leak repair cost if water is already coming in.
Sources
- HomeGuide — Roof Replacement Cost (edited Nov 7, 2025)
- Angi — How Much Does Roof Replacement Cost? (updated Mar 5, 2026) and Seattle page (updated Aug 4, 2026)
- Seattle SDCI — Re-Roof Permit
- Washington Department of Revenue — Custom construction; Seattle rate change, January 1, 2026
- L&I — Hiring a Contractor
- RCW 18.27.114 — Disclosure statement
All sources accessed October 14–15, 2026.
This guide summarizes published cost estimates and rules. It is not legal advice and not a quote. Get written estimates from licensed, bonded and insured roofers before deciding. See our disclosure and disclaimer.