The most frequent mistakes in roofing quotes
Written by Marc D., GCT Expert Analyst · Updated February 2026 · 3 min read
A poorly drafted roofing quote is a major financial risk. Here are the 9 recurring mistakes our analysts identify every week.
Why a poorly drafted quote costs you
Of 100 roofing quotes analyzed by our advisors in 2025, 84 contained at least one significant error or omission. In one in three files, the quote's grey zone allowed the contractor to invoice $1,500 to $6,000 in extras once work began.
Here are the nine recurring mistakes we see.
1. The actual roof surface is not stated
Without documented sq ft, comparing two quotes is impossible. Demand the mention "Estimated surface: X sq ft" on the first page.
2. Materials are not specified
"Premium shingle" means nothing. The quote must mention:
- Brand (BP, IKO, GAF, Malarkey…)
- Exact model (e.g.: Mystique 42, Cambridge XPress)
- Chosen colour
- Manufacturer warranty in years
3. The underlayment and eave membrane are missing
In Québec, the self-adhered eave membrane is essential to protect against ice dams. The quote must specify:
- Coverage height (3 or 6 ft from the eave)
- Presence in valleys
- Type of underlayment over the rest (synthetic recommended)
4. Ventilation is not addressed
A good quote describes existing ventilation, proposes corrections if needed, and prices new vents. A quote silent on ventilation often hides a risk transfer.
5. Flashings are not detailed
Chimney, dormers, party wall, plumbing vents: each flashing must be named. "Flashings included" is insufficient.
6. Damaged-decking handling is ambiguous
A good quote specifies:
- How many plywood sheets are included (often 2 to 4)
- Unit price beyond that ($50 to $95)
- Whether decking inspection is mandatory or "only if visible"
7. Warranties are verbal or vague
Beware of:
- "10 years" without specifying install or material
- "Written warranty delivered at the end"
- "Full coverage" without listed exclusions
A separate written installation warranty, signed by the company, is non-negotiable.
8. Municipal permit and disposal fees are excluded
More than 60% of quotes exclude these fees. A residential roof permit in Québec costs $75 to $350 depending on municipality. Material disposal can add $200 to $500.
9. Payment terms are risky
Refuse:
- Any deposit over 10% of the contract
- Full payment on material delivery
- The absence of a minimum 10% holdback at the end for defects
Sound-quote checklist
| Element | Present? |
|---|---|
| RBQ number + civic address | ☐ |
| Surface in sq ft | ☐ |
| Brand + model of shingles/membrane | ☐ |
| Detailed underlayment and eave membrane | ☐ |
| Ventilation described | ☐ |
| List of flashings | ☐ |
| Damaged decking: unit price | ☐ |
| Permit included or excluded (clear) | ☐ |
| Written installation warranty (years) | ☐ |
| Execution timeline | ☐ |
| Payment terms (deposit ≤ 10%) | ☐ |
| Signature and date | ☐ |
If even one element is missing, request a revision before signing.
FAQ — Roofing quotes
Does a quote have a validity period?
Yes, generally 30 days. Beyond that, the contractor may adjust the price based on material costs.
Should I sign the quote or a separate contract?
In Québec, for a home contract over $25, a formal contract is required. It must include your 10-day cancellation right.
Can a quote be reviewed before signing?
Yes. That is precisely GCT Expert's role. An independent analysis takes 24 to 48 hours and costs a fraction of the risk.
Received a roofing quote?
Have your quote reviewed before signing. GCT Expert helps Québec homeowners better understand prices, contracts and risks tied to roofing work.
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