Proposal Comparison Worksheet
A structured framework for comparing commercial roofing proposals across the dimensions that actually determine long-term value.
Comparing commercial roofing proposals on price alone is one of the most expensive mistakes a building owner can make. Two proposals for the same building can differ by $50,000 — and the lower-priced one might actually cost more over the life of the roof because it specifies thinner membrane, less insulation, a weaker warranty, or excludes critical scope items. The comparison framework below ensures you evaluate every proposal on the same criteria.
Before using this worksheet, review our guide to reading commercial roofing proposals to understand what each proposal element means and why it matters.
The Comparison Framework
For each proposal you receive, extract the information for every row in the table below. If a proposal does not specify a particular item, mark it as "Not Specified" — which is itself valuable information. A complete proposal addresses every element. Missing information often means the contractor has not fully planned the project or is leaving scope gaps that will become change orders.
| Comparison Item | Proposal A | Proposal B | Proposal C |
|---|---|---|---|
| Membrane System | |||
| System type (TPO, PVC, EPDM, etc.) | — | — | — |
| Manufacturer | — | — | — |
| Membrane thickness (mil) | — | — | — |
| Membrane color | — | — | — |
| Attachment method (mech. / adhered) | — | — | — |
| Insulation | |||
| Insulation type (polyiso, EPS, XPS) | — | — | — |
| R-value | — | — | — |
| Meets current energy code? | — | — | — |
| Cover board specified? | — | — | — |
| Scope | |||
| Tear-off or recover? | — | — | — |
| Area (square footage) | — | — | — |
| Existing layers to remove | — | — | — |
| Deck repair included? | — | — | — |
| Flashings and Details | |||
| Wall flashings included? | — | — | — |
| Pipe boots and penetration flashings | — | — | — |
| Curb flashings (HVAC, skylights) | — | — | — |
| Edge metal (standard, e.g., ES-1) | — | — | — |
| Drain replacement noted? | — | — | — |
| Warranty | |||
| Warranty type (material / system / NDL) | — | — | — |
| Warranty term (years) | — | — | — |
| Warranty issuer (manufacturer) | — | — | — |
| Workmanship warranty (contractor) | — | — | — |
| Pricing | |||
| Total project cost | — | — | — |
| Cost per square foot | — | — | — |
| Payment terms | — | — | — |
| Estimated project duration | — | — | — |
How to Use This Worksheet
- Gather all proposals. Request at least three proposals from qualified commercial roofing contractors. Ensure they have all visited the building and measured the roof — never accept a proposal based on satellite imagery alone.
- Fill in every cell. Extract the information from each proposal and enter it in the appropriate column. If a proposal does not specify an item, contact the contractor and ask for clarification before completing the comparison.
- Normalize the scope. Before comparing prices, verify that all proposals are bidding the same scope. If Proposal A includes a tear-off and Proposal B specifies a recover, the prices are not comparable without adjustment.
- Evaluate the gaps. A complete proposal is a signal of a thorough contractor. Missing specifications — especially membrane thickness, insulation R-value, warranty type, and scope (tear-off vs. recover) — should be resolved before signing.
- Calculate cost per square foot. Divide total cost by the specified roof area for an apples-to-apples price comparison. If the areas differ between proposals, ask why.
The Most Common Comparison Mistakes
- Comparing 60 mil to 80 mil membrane without adjusting price. The thicker membrane costs $0.30-0.60/SF more but typically adds 5-8 years to the service life. Calculate the annual cost of each option (total cost divided by expected life) for a true comparison.
- Ignoring warranty type differences. An NDL warranty adds 5-10% to project cost but covers 100% of future repair costs. A material-only warranty covers roughly 30% of a typical claim. The NDL premium often pays for itself on the first claim.
- Accepting a recover bid against tear-off bids. A recover costs less upfront but may not last as long, may not trigger the manufacturer's best warranty options, and can mask existing moisture problems. Compare lifecycle cost, not just first cost.
- Overlooking the insulation specification. A proposal that specifies R-15 when the energy code requires R-25 will face a change order during the project, or the building may fail final inspection.
Related Resources
- How to Read a Commercial Roofing Proposal — Understand every element of a proposal
- Contractor Credentials Guide — What qualifications to look for
- Red Flags in Roofing Proposals — Warning signs that indicate problems
- NDL Warranties Explained — When the warranty premium is worth it