THE ESTIMATING ANSWER
For one low-slope extension roof, start with a defined scope and measurement basis. Measure net roof area, upstands, penetrations, drainage falls and perimeter edge length. Identify membrane system, insulation if selected and outlet components separately. Price the listed tasks separately and state the condition that would require a revision: A wet or unsound deck changes replacement quantity and system specification.
This guide uses one low-slope extension roof as a worked, fictional job. Its matching itemized estimate and PDF let you trace the advice to actual document lines. The role considered here is roofing contractor. Confirm the site conditions, product selections and your own costs before preparing a client quote.
1. Define the measured job
Replace the waterproof membrane on one accessible low-slope extension roof with defined edge and outlet details. Measure net roof area, upstands, penetrations, drainage falls and perimeter edge length. Record the measurements and existing condition in the estimate before turning quantities into line items. The scope should make clear why this is a separate project from a broader renovation or maintenance quote.
Measurement basis: Measure net roof area, upstands, penetrations, drainage falls and perimeter edge length.
2. Build a product and labor schedule
Identify membrane system, insulation if selected and outlet components separately. This example has 7 distinct lines, including access and temporary weathering, old membrane removal, deck preparation. Use actual supplier prices and labor inputs for a customer job; the displayed amounts are fictional document inputs.
Selections to confirm: Identify membrane system, insulation if selected and outlet components separately.
3. Sequence the work and handoffs
Inspect deck condition after stripping and maintain temporary weather protection. Show which task depends on access, a selected product or another trade. If that dependency is still open, label the price preliminary and identify the information needed before a firm quote.
Work sequence: Inspect deck condition after stripping and maintain temporary weather protection.
4. Set a change boundary
A wet or unsound deck changes replacement quantity and system specification. The example excludes roof deck reconstruction, structural falls correction or interior repairs. Record the discovery, agree the revised work and update the estimate before adding it to the job.
If the job changes: A wet or unsound deck changes replacement quantity and system specification.
Worked project calculation
The example line for old membrane removal is 420 sq. ft. × $6.00 = $2,520.00. This line is one part of the complete 7-item estimate and uses a fictional unit rate.
The paired estimate has 7 separate lines. For this fictional job, multiply each quantity by its unit price and add the line amounts to get $16,940.00. The sample PDF uses these exact values, with tax and markup left at zero so the arithmetic is visible. This total is an illustration, not a regional price or an offer to perform the work.
| Cost line | Quantity | Unit price | Line amount |
|---|---|---|---|
| Access and temporary weathering | 1 job | $650.00 | $650.00 |
| Old membrane removal | 420 sq. ft. | $6.00 | $2,520.00 |
| Deck preparation | 420 sq. ft. | $4.00 | $1,680.00 |
| Membrane system allowance | 460 sq. ft. | $11.00 | $5,060.00 |
| Membrane installation | 420 sq. ft. | $13.00 | $5,460.00 |
| Upstands and outlet details | 1 job | $1,150.00 | $1,150.00 |
| Waste and final check | 1 job | $420.00 | $420.00 |
| Illustrative subtotal | $16,940.00 | ||
Scope and pricing boundaries
Replace the waterproof membrane on one accessible low-slope extension roof with defined edge and outlet details.
Outside this example: No roof deck reconstruction, structural falls correction or interior repairs.
Separately identify supplier allowances, labor, subcontracted work and site-specific risk where they apply. Before giving a selling price, decide how your own overhead, profit and any applicable tax will be handled. Do not copy the fictional rates into a real quote without checking your own measurements and supplier or subcontractor figures.
Before you send the estimate
- Measure net roof area, upstands, penetrations, drainage falls and perimeter edge length.
- Identify membrane system, insulation if selected and outlet components separately.
- Inspect deck condition after stripping and maintain temporary weather protection.
- A wet or unsound deck changes replacement quantity and system specification.
Read the complete flat roof membrane replacement PDF example to see how the scope, individual prices and exclusions appear in a client-facing document. If a condition is still unknown, write that boundary into your estimate and revise the affected line once it is resolved.
Questions about this estimate
Which quantity controls this flat roof membrane replacement estimate?
Measure net roof area, upstands, penetrations, drainage falls and perimeter edge length.
When should this flat roof membrane replacement quote be revised?
A wet or unsound deck changes replacement quantity and system specification. No roof deck reconstruction, structural falls correction or interior repairs.
TURN THIS EXAMPLE INTO YOUR OWN ESTIMATE
Build a flat roof membrane replacement estimate for your project
Use Estimates on iPhone or Android to draft a scope with AI assistance or enter each line yourself. Review quantities, rates, exclusions, and client details before exporting a PDF. The example is free to inspect; some app features may require an in-app purchase.
