A roofing price can include some deck replacement while leaving the final quantity uncertain. Before comparing bids, establish what the included allowance means and how additional work will be measured. “Decking included” and “decking extra” are too vague to support a useful cost comparison.
Before You Begin
GAF's August 2022 explanation of roof decking describes the supporting layer beneath the roofing components. It notes that reroofing does not automatically require new decking, but concealed conditions can lead to changes in the quoted work. This manufacturer article supplies background, not a current local code determination or a condition assessment for your roof.
Define The Unit Before Comparing The Rate
Ask each bidder to describe the material and the pricing unit. A sheet, an installed square foot and a linear foot of board are different quantities. Ask how partial sheets, cutting waste and minimum charges affect billing. Have the roofer explain the material appropriate to the actual assembly; do not choose thickness or fastening details from a generic allowance table.
Use these headings to compare the proposals:
| Item | What The Bid Should Explain |
|---|---|
| Included Allowance | Quantity and unit, or a stated dollar amount; identify where it sits in the base price |
| Material | Proposed material and specification, with substitutions handled explicitly |
| Additional Rate | Rate per defined unit, with labor, removal, disposal and applicable charges identified |
| Measurement Evidence | How the affected locations and final quantities will be documented |
| Unused Allowance | Whether any credit applies and how it is calculated under this agreement |
| Approval | Who receives the evidence and revised total before additional work is authorized |
An included quantity is not automatically a refundable cash allowance. Ask what the actual agreement says. A different material or supporting-framing repair may also fall outside the quoted unit rate; ask which conditions require a separate proposal.
Compare The Same Hypothetical Quantity
The following invented numbers demonstrate the calculation only. They are not market prices, recommended rates or an estimate of damage. Assume both bids cover the same materials and work, define a billable sheet identically and include all other charges for this example.
Swipe or scroll sideways to compare every column. Keyboard users can focus the table area and use the arrow keys.
| Fictional Bid | Base Price | Included Sheets | Rate For Additional Sheets | Total If Eight Sheets Are Needed |
|---|---|---|---|---|
| A | $12,000 | 4 | $120 | $12,480 |
| B | $12,150 | 6 | $90 | $12,330 |
Bid A adds four sheets: 4 × $120 = $480. Bid B adds two: 2 × $90 = $180. At this assumed quantity, B is $150 lower even though its base price is higher. If only four sheets are needed and neither agreement offers an unused-allowance credit, A remains $12,000 and B remains $12,150. The comparison changes with the agreed terms and actual quantity; neither scenario predicts the roof's condition.
Reconcile The Allowance With The Work Record
Request photographs identifying the affected roof sections, the measured quantity, the included amount and the additional amount. Obtain the revised total and any schedule impact in writing. Ask the roofer how the building will be protected while a decision or required inspection is pending. Do not climb onto the roof to count materials yourself.
California's CSLB contract guidance discusses recording changes in work, materials, completion date and price. California requirements should not be treated as nationwide law. Confirm the agreement and applicable local requirements for your project; this worksheet does not settle a disputed bill.
### Does A Low Unit Rate Make The Whole Bid Cheaper?
Not necessarily. Compare the base scope, included amount and treatment of the same assumed quantity. A low rate for a different material or incomplete scope is not an equivalent offer.
### What If The Quantity Is Still Unknown?
Keep it unknown. Agree on evidence and authorization, rather than converting an allowance into unlimited permission to proceed.
Use the roofing guide for the rest of the roof-system scope and the quote review for other missing terms.
Sources And Local Resources
Sources checked November 9, 2026. Confirm current requirements with the authority responsible for your property.