How to Write a Roofing Estimate

Start with measurements you can defend

Every number on a roofing estimate traces back to the measurements, so get those right before you price anything.

Aerial reports vs measuring by hand

Aerial measurement reports, built from satellite or aircraft imagery, give you plane-by-plane areas, pitches and the lengths of ridges, hips, valleys, rakes and eaves without setting up a ladder. They're fast and keep you off the roof for the first pass. Their limits matter: trees and shadows hide edges, the imagery can predate an addition, and no picture from above shows how many layers are on the roof, what the decking looks like or whether the flashing can be reused.

Hand measuring takes longer but catches what imagery can't. Two approaches work:

• Plane by plane on the roof. Measure each plane, then every ridge, hip, valley, rake and eave run, and sketch it with the dimensions.
• Footprint from the ground. Measure the building's outline including the overhangs, then multiply by the pitch multiplier below. This works for any roof where every plane has the same pitch, hips and valleys included. Measure sections with a different pitch separately.

Whichever you use, confirm it on site and attach the report or your sketch to the estimate. If you use a drone for measurements or photos, flying it for your business generally falls under the FAA's small drone rule (Part 107), which requires a Remote Pilot Certificate ¹.

Squares, pitch and waste

Roofing is ordered and priced in squares, and one square is 100 square feet of roof surface. Roof pitch is the rise in inches for every 12 inches of run, and it's what turns a flat footprint into real surface area. The multiplier is the square root of (144 plus the rise squared), divided by 12:

Waste is where two honest estimates drift apart. A plain gable roof has few cuts. Hips and valleys need an angled cut on every course, and dormers, skylights and short runs add more. Set your waste factor per roof from your own history (compare what you ordered with what you used on finished jobs) and show it as its own number instead of burying it in the squares. Decide whether starter and ridge cap come out of the waste or get their own linear-foot lines, and say which, so nobody counts them twice. Turning these quantities into a price is covered in how to price roofing jobs.

Example: A hip roof's footprint, overhangs included, is 2,000 square feet, and every plane is 6/12. Surface area is 2,000 × 1.118 = 2,236 square feet, or 22.36 squares. Say your records on cut-up hip roofs support a 12% waste factor (an illustrative figure, not a standard): 22.36 × 1.12 = 25.04 squares to order, rounded up to full bundles. The estimate shows 22.36 measured squares, the 12% waste factor and the order quantity as three separate numbers.

The line items homeowners and adjusters expect

A single "replace roof" price invites doubt. Line items let a homeowner compare bids item by item and let an adjuster match your scope to theirs. Use the unit each item is installed in:

Don't fold steep or high roof labor into the shingle price. In residential construction, OSHA requires employers to protect workers 6 feet or more above a lower level with guardrails, safety nets or personal fall arrest systems, unless another part of the rule allows an alternative ². Anchors, harness time and slower production on a steep pitch are real labor, so they belong on their own line.

List exclusions just as clearly: gutters, skylight replacement, siding repairs at sidewalls, interior repairs and anything else you aren't doing should be marked excluded or priced as an option.

Spec the materials and get the color in writing

The FTC tells homeowners that a written estimate should describe the work, the materials, the completion date and the price ³. On a roof, "materials" means a spec another crew could order from:

• Shingle manufacturer, product line, type (such as laminated architectural or three-tab) and color name.
• Underlayment type, ice barrier membrane, starter and hip and ridge products.
• Drip edge and flashing metal, gauge if you specify one, and color.
• Vent types (ridge, box, soffit intake) and quantities.
• A substitution clause: if a product is unavailable, you'll propose an equal and get written approval before installing it.

Have the homeowner sign off on the color name in writing, by signature or a text reply. Once shingles are nailed, a color dispute is expensive to settle.

Price decking as a per-sheet allowance

You usually can't see the decking until the old roof is off, so don't guess with a lump sum. State how many sheets the base price includes (zero is fine), the installed price for each additional sheet, and how you'll document replacements: photos of each bad sheet before it's covered and a count the homeowner can check. Get the homeowner's approval on the count before you dry in, by text with photos if they aren't home. Anything past the allowance is a change and should be handled like one; see how to handle change orders.

Example: Your estimate includes 2 sheets of decking and lists $100 per additional sheet installed (round numbers for the math). Tear-off turns up 7 soft sheets. You photograph each one, text the photos and the count to the homeowner and get approval for 5 extra sheets: 5 × $100 = $500, added by change order before the new underlayment goes down.

Code items to check before you price

Many states and cities build their residential code on the International Residential Code (IRC) and amend it, so confirm which edition your building department enforces. The section numbers below come from recent IRC editions.

• Drip edge. The IRC requires drip edge at the eaves and rake edges of shingle roofs, with adjacent pieces lapped at least 2 inches and the underlayment over the drip edge at eaves and under it at rakes (R905.2.8.5) ⁴. A missing drip edge on the old roof is no reason to leave it off the new one. Price it as its own linear-foot line.
• Ice barrier. Where the jurisdiction has designated a history of ice forming along the eaves and backing up water, the IRC requires an ice barrier from the lowest edges of the roof to at least 24 inches inside the exterior wall line (R905.1.2) ⁵. Deep overhangs can push that past one roll width.
• Low-slope sections. Asphalt shingles are allowed only on slopes of 2:12 or steeper, and slopes from 2:12 up to 4:12 need double underlayment (R905.2.2) ⁶. Check porch roofs, additions and dormers. A section under 2:12 needs a different roofing system and its own line.
• Ventilation. For vented attics, the IRC's baseline is net free vent area equal to 1/150 of the vented space, reducible to 1/300 when the code's conditions are met, including a split between high and low vents (R806.2) ⁷. Each vent product lists its net free area, so add up what you're specifying and check it against the requirement.
• Crickets. A chimney or penetration more than 30 inches wide, measured perpendicular to the slope, needs a cricket or saddle on its ridge side, covered in sheet metal or the roof covering (R903.2.2) ⁶. If a wide chimney has none, building one is its own line.
• Layers. The IRC doesn't allow a roof recover (new roofing over old) where the existing roof has two or more layers, is water-soaked or deteriorated, or is slate, clay, cement or asbestos-cement tile (R908.3.1.1) ⁸. Count layers at an edge during the inspection and price tear-off per layer.
• Permit and inspection. Ask the building department whether a re-roof needs a permit, list the fee, and state that you'll pull it and schedule the inspection. The FTC lists a contractor asking the homeowner to get the required building permits among the signs of a home improvement scam ³.

Example: The eave overhang measures 2 feet along the slope and your ice barrier comes in 3-foot rolls. Covering the overhang plus 24 inches inside the wall line takes at least 4 feet, so one course falls short and every eave needs two. On 120 feet of eaves, that's 240 linear feet of membrane instead of 120, before laps.

Example: An attic over a 1,500-square-foot ceiling needs 10 square feet (1,440 square inches) of net free vent area at 1/150. If the 1/300 exception applies, it needs 720 square inches, split between upper vents and low intake as the code describes. Compare those totals with the net free area ratings of the ridge vent and soffit vents on your estimate.

Photos that back up every line

Photos turn line items into evidence. Before you write the estimate, take:

• Each slope, so the whole roof is accounted for.
• Damage close-ups with something for scale, such as a tape measure or a chalk circle around each hit.
• The edge where you counted layers.
• Flashing at chimneys, walls and skylights, plus every pipe boot and vent.
• The attic: underside of the deck, stains, daylight and the existing vents.
• Interior ceiling stains, gutters and downspouts.

Caption each photo with the line item it supports and attach the set to the estimate. On insurance work, an item with no photo behind it is an item you'll be asked to prove later.

Workmanship warranty vs manufacturer warranty

Homeowners mix these two up, so the estimate should separate them in plain words.

• Your workmanship warranty covers your installation. State how many years, what counts as a workmanship defect (such as a leak from flashing or nailing), what doesn't (storm damage, other trades working on the roof, later alterations), whether it transfers to a new owner and how to make a claim.
• The manufacturer's warranty covers the products under the manufacturer's own document. Name it, attach or link its terms and describe coverage the way the document words it, including how it defines terms like "lifetime" and any proration. Check whether coverage depends on following the installation instructions, registering the roof or meeting ventilation conditions, and then do what it requires.
• If you offer an enhanced warranty through a manufacturer's contractor program, list it by its official name and say who registers it.

Don't promise more than either document says. Have a lawyer review your workmanship warranty wording once, since it becomes part of the contract.

Payment schedule and contract terms

Roof jobs move fast once materials are ordered, so put the payment schedule on the estimate: what's due at signing or when materials are ordered, and what's due at completion. Deposit size and timing are covered in how much deposit to ask for. The FTC tells homeowners not to pay the full amount up front and notes that some states limit how much a contractor can ask for as a down payment ³, so check your state's home improvement rules before you set yours.

Also include:

• Your name, address, phone and license number, plus estimated start and completion dates, which the FTC tells homeowners to look for in a contract ³. Say how weather delays are handled.
• How long the price holds.
• The decking allowance and your change-order process.
• Cancellation rights. If the homeowner signs at home, the FTC's Cooling-Off Rule can give them until midnight of the third business day to cancel qualifying sales of $25 or more ⁹. Don't order materials or book the crew until that window closes.

On insurance jobs, write the schedule so it fits how the claim pays out. How to invoice roofing jobs covers actual cash value, recoverable depreciation and mortgage-company checks.

Insurance estimates: match the adjuster's scope

On a claim, the homeowner will set your estimate next to the adjuster's. Make the comparison easy:

1. Get the adjuster's estimate from the homeowner and read it before you finalize yours.
2. Mirror its structure. Use the same roof sections, the same units and line names that map to theirs, so every difference stands out.
3. Give each difference a reason: a measurement (attach the report), a photo, a code section from the list above or a manufacturer installation requirement.
4. Send missed items through the homeowner's claim as a documented request. Items found at tear-off, like extra decking or a second layer, follow the same path. See insurance supplement.
5. Keep upgrades on separate lines that the homeowner pays for, such as a heavier shingle or ventilation beyond what code requires, so nobody reads your claim estimate as billing the insurer for them.

For code items, whether the policy pays depends on the homeowner's coverage, which may include ordinance or law (building code upgrade) coverage. Ask the homeowner to check their declarations page and confirm with their insurer.

Remember whose claim it is. The FTC tells homeowners dealing with storm damage to get written estimates from more than one contractor and to ask for an explanation when prices differ a lot ¹⁰. Your line-by-line comparison is that explanation. Before you talk to an insurer on a homeowner's behalf, check your state insurance department's rules on what contractors may do in a claim.

Before you send it

• Measurements confirmed on site, with the report or sketch attached.
• Measured squares, pitch and waste factor shown separately.
• Every line has a unit, a quantity and a photo or code basis.
• Shingle product line and color named and approved in writing.
• Decking allowance and per-sheet price stated.
• Code items checked against the adopted edition, permit listed.
• Exclusions listed.
• Both warranties described, with the manufacturer's terms attached.
• Payment schedule, price validity and cancellation terms included.
• On claims, the adjuster's estimate compared line by line.