Step 1: Measure in squares
Roofers price and order by the roofing square: 100 square feet of roof surface. Measure each plane, account for pitch (a steeper roof has more surface than its footprint), and add them up. Also measure the linear feet of eaves, rakes, ridges, hips and valleys, because starter, drip edge, ridge cap and valley materials are ordered by length, not by square.
Owens Corning's re-roofing guide confirms that a roofing square is 100 square feet and that shingles are generally packaged three bundles per square. Not every product follows that rule, so check the bundle coverage on the shingle's spec sheet. IKO, for example, notes that three bundles of some shingles may cover less than a full square, which can leave you short.
Step 2: Add waste and order materials
Cut shingles at hips, valleys, walls and edges are wasted. Owens Corning suggests adding 10% to 15% to material totals as a rule of thumb, and more on cut-up roofs. A simple gable needs less; a roof with many hips, valleys and dormers needs more.
Example: a roof measures 24 squares. With 10% waste, that is 26.4, so order 27 squares, or 81 bundles at three per square. Then add starter, ridge cap, underlayment, ice and water barrier where your code or climate calls for it, drip edge, flashing, vents, pipe boots and nails.
Step 3: Labor, overhead and the rest of the costs
- Crew labor: crew size times hours, at each worker's burdened labor rate. Include tear-off, dry-in, install, cleanup and magnet sweep. Add time for steep pitch, multiple layers or difficult access.
- Overhead: many roofing shops recover overhead per crew day: yearly overhead divided by the crew days you actually work.
- Disposal: dumpster or dump trailer and dump fees. Fixr's roof guide puts removal and disposal around $50 per square on average, up to $150 per square for heavy materials or multiple layers. That figure varies by location; use your local dump fees.
- Permit: the local fee and the time to pull it and meet the inspector.
- Sales commission if your salesperson is paid a share of the price.
Step 4: Worked example, 24-square architectural shingle roof
Example numbers only, for a single-layer tear-off on a walkable pitch.
| Line | How it is figured | Cost |
|---|---|---|
| Shingles | 81 bundles x $38 | $3,078 |
| Other materials | Underlayment, ice and water, starter, ridge, drip edge, vents, boots, nails | $1,450 |
| Crew labor | 5 roofers x 2 days x 9 hours = 90 hours x $42 burdened | $3,780 |
| Overhead | 2 crew days x $900 | $1,800 |
| Disposal | Dumpster and dump fees | $650 |
| Permit | Local fee (example) | $300 |
| Total cost | $11,058 |
Target net margin 20%, sales commission 8% of price. Commission is a share of the price, so it goes in the divisor: $11,058 / (1 - 0.20 - 0.08) = $11,058 / 0.72 = $15,358, rounded to $15,360. That is $640 per measured square, or $6.40 per square foot.
As a check, Fixr's 2026 guide gives a national average around $4.75 per square foot, with a range of $3.75 to $11, and says costs vary by location, with coastal and urban areas typically paying more than rural ones. The example sits inside that range. Run your own job through the job pricing and markup calculator.
Step 5: Handle decking and hidden damage up front
Nobody knows how much rotted decking is under the old shingles until it is torn off. Do not guess and bury it in the price. Instead:
- State how many sheets of decking are included (zero is fine).
- Give a per-sheet unit price for replacement, for example $95 per sheet installed, in the estimate.
- Have the crew photograph damaged decking before replacing it, and get the customer's OK in writing as a change order.
The same goes for extra layers found at tear-off, rotted fascia and damaged flashing that cannot be reused.
Step 6: Put the estimate together
- Measurements and squares, so the customer can compare quotes apples to apples.
- Shingle line and color, underlayment, ventilation and flashing details.
- What is included: tear-off, disposal, permit, cleanup.
- Unit prices for decking and other unknowns.
- Options, for example a standard shingle, an upgraded shingle and an upgraded system with better underlayment and ventilation.
- Payment terms and deposit, and an expiration date.
Common mistakes
- Measuring the footprint instead of the roof surface.
- Forgetting linear-foot materials like starter, ridge and drip edge.
- Assuming three bundles always cover a square.
- Pricing a second layer or a steep pitch the same as a simple tear-off.
- No unit price for decking, so the crew eats it or the customer is surprised.
How SWITCHBOARD handles this
With Job Walk in SWITCHBOARD, the estimator walks the roof area by area with photos, video and voice notes, adds lines from your own Price Book, and has Good, Better and Best options ready at the end, with live margin against your target. SWITCHBOARD does not measure roofs from aerial images; you enter your own measurements. See the roofing page.
Questions people ask
How many bundles of shingles are in a square?
Many common asphalt shingles are packaged three bundles per square, but some products differ or cover slightly less than 100 square feet. Check the manufacturer's spec sheet.
What waste factor should I use on a roof estimate?
Owens Corning suggests 10% to 15% as a rule of thumb. Use the low end for simple gable roofs and more for roofs with many hips, valleys and dormers.
How should I price rotted decking I cannot see?
Put a per-sheet unit price in the estimate, photograph the damage at tear-off, and get the customer's written OK before replacing it.
Should roof estimates include the permit?
Yes. Include the fee and the time to pull it, and say in writing that it is included so the customer can compare quotes fairly.
Sources
- DIY Roofing: Re-Roofing Tips | Owens Corning Roofing (checked November 10, 2026)
- Bundles Of IKO Shingles in a Square (checked November 10, 2026)
- How Much Does a Roof Replacement Cost in 2026? | Fixr.com (checked November 10, 2026)