How to Compare Roof Estimates When the Totals Don't Match

Updated 2026-10-24 · Sources checked

"i had to pay extra as some of the decking had to be replaced that wasnt anticipated."

A commenter in a roofing thread described that surprise.

Compare the lines, not the totals. Two bids can differ because one prices work the other leaves out, and that gap is where surprise charges hide. Ask every roofer to put the same items on paper: the work, the materials, the completion date and the price¹. Once every bid answers the same questions, the differences become choices you can weigh.

Quick answer:

Ask each roofer for the scope of work, materials, start and completion dates, and payment terms² in writing.
Check that every bid says what happens to the old roofing, the flashing and any damaged wood³.
Ask how hidden damage is priced and approved before the crew opens the roof.
Treat the lowest bid⁴ as a question: find out what it leaves out.

On this page

What should a written roof estimate say?
Lines that explain a gap between two bids
What if the crew finds rotted decking when the roof is opened up?
Should you skip the cheapest bid?
A checklist for the quotes you are getting
Quick questions

Today you can email each roofer the same list of items and ask them to fill in whatever is missing.

What should a written roof estimate say?

It should name the work, the materials, the dates and the price, so several bids can be set side by side¹. Payment terms belong on the list too, because they are part of what you are agreeing to². In North Carolina, homeowners are told to ask for a breakdown of the costs and the warranty details⁵.

A single number with a two-line description gives you nothing to compare. One reply in a thread put the fix in six words: "You should ask for a breakdown."

Promises made out loud count for little once the job starts. Get all promises in writing⁶ and spell out exactly what the contractor will and will not do.

Not sure which items have to appear on the estimate? What is included in a roof replacement.

Lines that explain a gap between two bids

When two totals are far apart, look first for items one bid has and the other lacks. Three are worth checking on every estimate.

Tear-off. This means stripping the old roofing before the new goes on. One voluntary high-wind home standard describes a full replacement as one that will remove all existing roofing material and replace any damaged wood³. If a bid does not say exactly what would be done with the old layers, ask.

Flashing. This is the material that seals the joints and edges of a roof, where water likes to find a way in. The same standard lists proper flashing at penetrations, roof/wall intersections, valleys, gables and eaves³. Treat that as an example of lines to look for. If one bid skips flashing, ask why before assuming it is a bargain.

Damaged wood. This is the next section, because it is where a fair-looking bid can leave you having to pay extra.

What if the crew finds rotted decking when the roof is opened up?

Then the price can change after the job starts, so get the rule on paper before it does. Decking is the wood boards under the shingles. Once the old roofing is off, a crew can find boards that have to be replaced, which is the case in the opening quote.

One Oklahoma state-program form names rotted decking and structural damage as examples of an unforeseen field condition⁷. That form is a change order: a signed paper that records the extra work and what it costs. On it, extra work is agreed by signing, and both parties accept the changes in scope, cost and schedule⁷ written there.

Another commenter described the line to look for: "any roofing estimate should have a line item declaring cost of repairs like replacing the decking". Ask each roofer to put the decking price and the approval step in writing. The Quote Decoder below writes a message for each roofer, from the quotes you enter.

If a roofer won't put this in writing, that is an answer too: weigh it against the bids that do.

One bid prices the wood and another leaves it out? What roof rot means and what to get in writing.

Should you skip the cheapest bid?

Not automatically, but find out what it leaves out. The trade association for roofing contractors advises a healthy skepticism about the lowest bid⁴, and says price is only one criterion for choosing a roofer.

Skepticism means asking questions, not throwing the bid away. Hold it against the others line by line. If it doesn't have a line item for removing the old roofing or for damaged wood, ask what happens when those come up. In Texas, getting more than one bid helps show which offers are too high or too good to be true⁸.

A checklist for the quotes you are getting

Put your bids in a row and mark each item. Anything not specified in a roofer's estimate becomes a question for that roofer.

Work and materials: whether the old roofing comes off, the new materials, the flashing, and how damaged wood is handled.
Dates and payment terms: start and completion dates and when payments are due².
A cost breakdown and warranty details written out, not just a total⁵.
Extra work: how hidden damage is priced, and a signed change order before it goes ahead.
The roofer: license checked with your state or county, proof of insurance and a written contract⁹, plus who applies for the permit.

If a line is missing, send every roofer the same email and ask them to add it. Wait for the answers before you compare totals. Avoid high-pressure sales tactics or contractors who demand full payment upfront².

Already picked a bid and wondering what to check before you sign? What a roof replacement contract should say.

Roof Quote Decoder: compare your quotes side by side

Type in what your written quotes say. You'll see how they differ, what each one is missing in writing, and a message for each roofer. Nothing you type leaves this page.

This comparison needs JavaScript. Without it, check that each written quote includes: the work and materials, start and completion dates, a breakdown of the costs, the payment schedule, a signed change order before any extra, who pulls the permit, warranty details, proof of license and insurance and, for a replacement, a limit on hidden-damage extras before they stop and ask you, whether the old roofing is removed, the flashing work, cleanup, and a price per sheet of decking.

Quick questions

How many estimates should I get? At least 3 written estimates² is the advice from a building-safety research group. Three gives you a middle and an outlier to question.

What should I ask about the warranty? What it covers, how long it lasts and who stands behind it. Get the answers written into the estimate, not just heard from the estimator on the phone.

Can a calculator replace written estimates? A calculator gives a number without your roof's details. The price you pay depends on what each bid includes, so use written bids for the decision.

What if a roofer doesn't send the estimate? Send one reminder in writing, then move on. A bid that doesn't arrive cannot be compared.

What is the 25% rule? It is a Florida provision that covers a roof or roof section built, repaired or replaced under the 2007 Florida Building Code or later¹⁰. Once 25 percent or more of it is repaired, replaced or recovered, only that portion has to meet the code in effect¹⁰. If a roofer cites it on a bid, ask which code they mean and get the answer in writing. Outside Florida, ask your local building department.