A roof is the easiest trade to estimate badly, because almost everything about it is hidden until the shingles come off and almost every number depends on a measurement the homeowner cannot check. That combination produces two failure modes: estimates so padded they lose, and estimates so lean they win and then cost money.
This is a complete estimate for a real shape of job — a 28-square architectural shingle tear-off and replace on a 6:12 ranch with an attached garage, one existing layer, one chimney. Every line is shown with its unit, its rate and its arithmetic, and the parts that are genuinely unknowable are handled as allowances rather than as padding.
Start with squares, and be honest about waste
A roofing square is 100 square feet of roof surface — not floor area, not footprint. On a 6:12 pitch the roof surface is about 1.118 times the horizontal area it covers, which is where most self-taught estimates go wrong: somebody measures the house, gets 2,500 square feet of footprint, and forgets the pitch multiplier entirely.
That is a six-square swing between a shallow roof and a steep one on the same house — roughly $2,300 of shingles and labour at the rates below. Steep roofs also cost more per square to walk, which is a separate adjustment on top of the extra area, not the same one counted twice.
Then waste. Waste is a material number, not a quantity number. The roof is 28 squares; you will order about 30.5. Simple gables run 5–8%; a roof with hips, valleys and dormers runs 12–15% because every cut across a valley produces an offcut nobody can use. Starter and ridge cap come out of separate bundles and should be their own lines, not folded into the field count.
The estimate, line by line
Eight lines plus one allowance. A roofing estimate with thirty lines on it is not more thorough — it is a document the homeowner will compare to a one-page competitor and read as complicated.
Sales tax at 8.6% adds $1,423.08, bringing the total to $17,970.48. A 25% deposit is $4,492.62, which on this job is a little more than the materials cost — which is exactly what a deposit is for.
Two of those lines are worth arguing about, so put them where they can be argued about honestly.
The decking allowance is the whole document
Nobody can see the decking through the shingles. You can guess from the age of the roof and the state of the eaves, and you will be wrong sometimes in both directions. There are three ways to handle it and only one of them survives a bad surprise.
The allowance above is ten sheets at $78 installed. The sentence that goes with it is one line long: “If the deck needs more than ten sheets we will photograph it, tell you the count, and continue only when you say so; additional sheets are $78 each.”
That sentence is worth more than the $780. It converts the worst conversation on a roofing job — the one held on a torn-off roof with rain forecast — into a decision the homeowner already agreed to the shape of.
Tear-off is a disposal problem, not a labour problem
Estimators price tear-off by the square because that is how the labour scales, then get caught by the part that does not: the dumpster. One layer of architectural shingle runs roughly 250 pounds per square, so a 28-square tear-off is about 7,000 pounds — three and a half tons before you count decking, nails and felt.
Two layers is not double the labour but it is double the tonnage, and dumpster pricing steps rather than scaling smoothly. If your $62 a square assumed one layer and you find two, that is a change order with a real number behind it, not a judgement call. Say on the estimate which you assumed.
Every one of those has ended in an argument on somebody's job. Written on the estimate they cost you nothing; discovered on the day they cost a morning.
Flashing is where the leaks and the disputes both live
Reusing old step flashing is the single most common corner cut in residential roofing, and it is the reason a two-year-old roof leaks at a chimney. Price new flashing, say you are pricing new flashing, and say what the cheaper competitor is probably not pricing.
You do not have to name the competitor. “This estimate includes new step and counter flashing at the chimney. If you are comparing bids, check whether the other one reuses the existing flashing — that is usually the difference.” That sentence does more for your close rate than a discount, because it hands the client a question they can go and ask.
Exclusions on a roof
Four lines. These are not defensive boilerplate; each of them is a job somebody has eaten.
Interior damage is the important one. The homeowner with a stained ceiling assumes the new roof fixes it. It does not, and finding that out after the cheque has cleared is how a five-star job becomes a two-star review.
Say which warranty you mean
There are always two, and clients hear one. The manufacturer warrants the shingle against defect for a stated period, on stated conditions, and usually prorated. You warrant the workmanship, for a period you choose, and that is the one that actually matters — because the overwhelming majority of roof failures in the first decade are installation, not product.
Write both on the estimate with their years and their limits. “Lifetime warranty” with nothing after it is the phrase every bad roofer uses, so putting real numbers next to yours separates you from them at no cost.
Weather, timeline and the sentence about dry-in
A roof is the one trade where the client's house is genuinely open to the sky for part of the day, and their anxiety about that is legitimate. Two sentences fix it: what you do if weather turns mid-tear-off, and how much roof you open at once.
“We tear off only what we can dry in the same day. If weather turns, the exposed area is covered and fastened before the crew leaves.” Nobody else's estimate says that. It costs nothing, it is true of any competent crew, and it is frequently the reason a homeowner picks the second-cheapest bid.
Ventilation is a code item, not an upsell
Ridge vent appears on the estimate above at $525 and it is the line most likely to be cut by a homeowner comparing bids, because it sounds optional. It is not. Attic ventilation is a code requirement in most jurisdictions, it is a condition of most manufacturer shingle warranties, and it is the difference between a roof deck that lasts twenty-five years and one that cooks from underneath.
The usual rule is one square foot of net free ventilating area per 150 square feet of attic floor, halved to 1:300 when a vapour retarder is present or when the intake and exhaust are balanced between the soffit and the ridge. The number matters less than the balance: ridge vent with blocked soffits does not ventilate, it just pulls conditioned air out of the house through the ceiling.
If the soffits are painted shut or stuffed with insulation — and on a house old enough to need a roof, they often are — say so on the estimate with a price for opening them. A ridge vent installed above blocked intake is a line item you have been paid for that does nothing, and when the shingles fail early it is your workmanship the manufacturer will point at.
Gutters, and the sequencing question
Gutters are excluded on the estimate above, and that is the right call for most jobs, but the exclusion needs a sentence attached because the sequencing is not obvious to a homeowner. Drip edge tucks behind the gutter's back flange. If the gutters are being replaced, they should come off before the roof goes on and back after — which means either you are coordinating another trade, or the client is, and somebody needs to know which.
The failure mode is a homeowner who books gutter replacement for the following month, and the new gutter installer takes off the drip edge you just installed to get their hangers in. Now there is a detail nobody owns and a leak nobody will admit to.
“If you are planning new gutters, do them within two weeks of the roof and tell us — we will coordinate the drip edge detail with your gutter installer at no charge.” One sentence, no cost, and it prevents the most common post-roof callback in the trade.
If it is an insurance job, the document changes
Storm work runs on a different set of rules and the estimate has to reflect them. The homeowner is not really the buyer — the adjuster's scope is — and the number that matters is not your price but whether your scope matches theirs line for line.
The deductible line is not optional and it is not a formality. Offering to absorb, waive or rebate a homeowner's deductible is insurance fraud in most states and a licence matter in several — regardless of how it is described on the invoice. Put the deductible on the document as an amount the homeowner pays, and keep it there.
The supplement process is where the money is on these jobs, and it is a documentation exercise rather than a negotiation. Photograph the condition, cite the code section or the manufacturer instruction that requires the work, and submit it as a discrete item. An adjuster can approve a documented supplement in a day; an undocumented one becomes a phone call neither of you has time for.
Make your bid comparable on purpose
A homeowner with three roofing bids is holding three documents that describe different jobs in different units, and the only field all three share is the total. So the total is what they compare, and the most thorough bid loses to the least thorough one.
You cannot control what the other two look like. You can control whether yours is easy to line up against them.
Add one short paragraph at the end headed “What to check on the other bids” and list four things: the number of squares they measured, whether flashing is new or reused, whether tear-off assumes one layer, and what the workmanship warranty term is. It reads as confidence rather than as an attack, and it hands the homeowner a set of questions that will find the gaps in a thin bid without you ever naming a competitor.
From estimate to signed contract
When the client says yes, three things must carry across unchanged: the scope, the allowance wording and the exclusions. Retyping is where they get lost — a rate moves, the decking sentence goes missing, and the document that gets signed is not the document that was agreed.
The contract should start as a copy of the estimate with the range collapsed, the deposit terms added and a signature block on the end. If you find yourself retyping a roofing estimate into a contract, you are re-creating the most expensive kind of error a roofer can make: an agreed price with an unagreed scope underneath it.
