Direct Answer
Owners should evaluate roofing bids for a new commercial building by comparing the complete scope of work, exclusions, allowances, alternates, specifications, warranty requirements, schedule, qualifications, and total project risk—not simply by choosing the lowest price.
A low roofing bid can become expensive if important work is excluded, carried as an allowance, assigned to another trade, or left unclear. NRCA recommends requiring a written proposal with a complete description of the work and specifications and cautions owners against treating the lowest bid as the only selection criterion. :chatgpt-content-reference{index=”1″}
For new Florida commercial construction, the strongest bid comparison is a scope-to-scope comparison: verify that every contractor is pricing the same roof assembly, insulation package, attachment method, flashing, edge metal, drainage interfaces, penetrations, temporary protection, inspections, cleanup, closeout, and warranty requirements.
Who This Applies To
- Commercial property owners
- Real estate developers
- General contractors and construction managers
- Owners’ representatives
- Architects and design teams
- Commercial roofing contractors
- Construction lenders and asset managers
- Roof consultants and RROs
Not for: This is not a substitute for a project-specific roofing specification, construction contract, engineering review, or legal review. The final bid comparison should be based on the actual drawings, specifications, approved assemblies, contract documents, and project requirements.
1. Start with the base roofing scope
The first question should be: Are all contractors actually pricing the same roof?
Owners should compare each proposal against the roofing drawings and specifications line by line rather than comparing only the bottom-line price.
The base scope should identify items such as:
- Roof system type and manufacturer
- Membrane type and thickness
- Insulation type, thickness, and R-value
- Cover board
- Vapor retarder where required
- Adhesive or mechanical attachment
- Fasteners and plates
- Base sheets and underlayments where applicable
- Flashing
- Metal edge systems
- Copings and counterflashings
- Roof drains and associated roofing interfaces
- Scuppers and overflow conditions
- Pipe and equipment penetrations
- Equipment curbs
- Walk pads
- Expansion joints
- Roof accessories
- Temporary protection and weather protection
- Roof cleanup
- Testing and inspections
- Closeout documentation
- Manufacturer warranty requirements
A proposal that omits one of these items may initially appear cheaper while transferring the cost to another trade, a change order, or the owner.
2. Compare the proposed roof assembly, not just the membrane brand
Two contractors can both write “TPO roof” on their proposals while pricing substantially different systems.
Compare the complete assembly, including:
| Component | What the Owner Should Compare |
|---|---|
| Membrane | Type, thickness, manufacturer, color, reinforcement |
| Insulation | Type, thickness, number of layers, R-value, attachment |
| Cover board | Type, thickness, attachment and location |
| Attachment | Adhered, mechanically attached or hybrid system |
| Fasteners | Type, spacing, plates and approved assembly |
| Flashing | Base flashing, penetration flashing and transition details |
| Edge metal | Profile, gauge, attachment and applicable testing/approval |
| Drainage | Drains, scuppers, overflows and roofing interfaces |
| Accessories | Walk pads, equipment supports, expansion joints and other accessories |
The owner should also confirm that the proposed assembly corresponds with the project’s approved design and applicable code or product-approval requirements.
3. Review exclusions before comparing prices
Exclusions are one of the most important parts of a roofing bid.
Do not assume that an item shown on the drawings is included simply because it appears somewhere in the construction documents. Ask each bidder to provide a clearly written list of exclusions.
Common items requiring clarification include:
- Roof deck repair or replacement
- Structural reinforcement
- Concrete repairs
- Drain replacement
- Plumbing connections
- HVAC curb work
- Mechanical equipment relocation
- Electrical work
- Roof access equipment
- Temporary protection
- Interior protection
- After-hours work
- Crane or hoisting costs
- Dumpster and disposal charges
- Permit fees
- Testing
- Third-party observation
- Manufacturer inspection
- Warranty fees
- Existing-condition corrections
A bid with a long exclusion list is not necessarily a bad bid. The issue is whether the owner understands who is responsible for every excluded item.
4. Identify allowances
An allowance is not necessarily a fixed project cost. It generally represents an amount carried for work or materials that have not been fully defined at bid time.
Owners should identify every allowance and ask:
- What exactly does the allowance cover?
- What quantity was assumed?
- What unit price applies if the allowance is exceeded?
- What happens if the actual cost is lower?
- Are contractor overhead and markup included?
- Who approves changes to the allowance?
For example, if a contractor carries an allowance for roof-deck repairs, a $500,000 bid and a $520,000 bid cannot be compared fairly if the first contractor has a much larger deck-repair allowance embedded in the price.
5. Evaluate alternates separately from the base bid
Alternates should never be allowed to obscure the actual base price.
Ask every bidder to identify:
- Base bid
- Deductive alternates
- Additive alternates
- Unit prices
- Owner-requested options
- Value-engineering alternatives
- Manufacturer or system substitutions
Each alternate should explain exactly what changes from the base scope.
| Alternate | Owner Should Ask |
|---|---|
| Different membrane | Does thickness, warranty, attachment or performance change? |
| Additional insulation | What R-value is added and what is the lifecycle benefit? |
| Different cover board | Does fire, impact, attachment or warranty performance change? |
| Different roof assembly | Is the alternative code-compliant and manufacturer-approved? |
| Enhanced warranty | What additional inspections, maintenance or manufacturer requirements apply? |
| Value-engineering option | What performance, service-life or risk changes with the lower-cost option? |
6. Be careful with value engineering
The cheapest alternate is not automatically the best value.
A roofing VE proposal should be evaluated against:
- Initial construction cost
- Expected service life
- Warranty coverage
- Maintenance requirements
- Wind performance
- Energy performance
- Repairability
- Future replacement implications
- Compatibility with rooftop equipment
- Availability of replacement materials
The owner should ask the design professional or qualified roofing consultant to confirm that the proposed substitution maintains the project’s intended performance.
7. Compare what each contractor assumes other trades will do
Roofing interfaces are a common source of disputes on new commercial construction.
For example, determine who is responsible for:
- Setting HVAC curbs
- Installing equipment supports
- Flashing curbs
- Installing roof drains
- Connecting drain components
- Installing overflow scuppers
- Installing roof penetrations
- Sealing penetrations
- Installing edge metal
- Installing roof access hatches
- Installing fall-protection anchors
- Installing walkways
Every roof-to-trade interface should have one clearly identified responsible party.
8. Review the roofing contractor’s qualifications
Price should be considered only after confirming that the contractor is capable of performing the work.
NRCA recommends prequalifying roofing contractors and reviewing items such as business history, insurance, references, completed projects, project supervision and quality-control procedures. :chatgpt-content-reference{index=”2″}
For a new commercial building, owners should request:
- Relevant commercial project references
- Projects of similar size and complexity
- Experience with the specified roof system
- Manufacturer authorization where required
- Insurance certificates
- Licensing information
- Project superintendent information
- Quality-control procedures
- Safety record and program
- Warranty experience
9. Compare warranty coverage carefully
A warranty should be evaluated as part of the bid rather than treated as an afterthought.
Compare:
- Contractor workmanship warranty
- Manufacturer warranty
- Warranty term
- Warranty coverage
- Inspection requirements
- Maintenance requirements
- Exclusions
- Wind-related limitations
- Transferability
- Who pays for warranty inspections
- Who performs warranty repairs
NRCA advises owners to carefully read roofing warranties and understand the provisions that can void or limit coverage. :chatgpt-content-reference{index=”3″}
This is particularly important because exclusions can involve conditions such as unauthorized alterations, underlying substrates, drainage, maintenance, other trades, or improper installation. :chatgpt-content-reference{index=”4″}
10. Evaluate the schedule and temporary protection
A roofing bid should explain how the contractor will protect the building during construction.
Ask:
- When can roofing begin?
- How long will installation take?
- What weather limitations apply?
- How will unfinished areas be protected?
- Who is responsible for temporary dry-in?
- How will other trades access the roof?
- What happens if the roofing schedule is delayed?
- How are penetrations coordinated?
A low bid that assumes ideal weather and uninterrupted access may not be comparable to a bid that includes a realistic protection and sequencing plan.
11. Review submittals and closeout requirements
Owners should confirm that the roofing contractor has included the required submittals and closeout documents.
Depending on the project, this may include:
- Product data
- Shop drawings
- Roof assembly information
- Product approvals
- Safety data
- Samples
- Manufacturer documentation
- Inspection reports
- Testing records
- Warranty documents
- As-built information
- Maintenance instructions
- Photographic documentation
- Final roof plans and details
Industry guidance recognizes project submittals as an important part of the design, prebid, bidding, preconstruction, construction and closeout process. :chatgpt-content-reference{index=”5″}
12. Use a bid leveling matrix
The easiest way for an owner or developer to compare multiple roofing bids is to create a bid-leveling matrix.
| Category | Bidder A | Bidder B | Bidder C |
|---|---|---|---|
| Base roof system | Included | Included | Included |
| Insulation | Compare specification | Compare specification | Compare specification |
| Cover board | Included | Alternate | Excluded |
| Flashing | Included | Included | Clarification required |
| Edge metal | Included | Included | Alternate |
| Drainage interfaces | Included | Excluded | Allowance |
| Manufacturer warranty | Included | Included | Alternate |
| Contractor warranty | 10 years | 10 years | 5 years |
| Inspection/QA | Included | Excluded | Allowance |
| Closeout documents | Included | Included | Clarification required |
| Base price | $— | $— | $— |
The goal is to convert three apparently different proposals into three comparable scopes.
13. Watch for unusually low bids
A significantly lower bid deserves investigation rather than automatic acceptance.
Ask:
- Was the specification interpreted correctly?
- Were all drawings reviewed?
- Are important materials excluded?
- Are there unusually low allowances?
- Are manufacturer inspections included?
- Is the warranty comparable?
- Are other-trade interfaces excluded?
- Are permits or fees excluded?
- Are temporary protection and weather protection included?
- Is the contractor proposing a different assembly?
NRCA specifically cautions owners to maintain a healthy skepticism toward the lowest bid because price is only one criterion in contractor selection. :chatgpt-content-reference{index=”6″}
14. The owner should ask every bidder the same clarification questions
Before making the award, send the same clarification list to every bidder.
At minimum, ask each contractor to confirm:
- We have included the complete roofing specification.
- We have included the specified roof assembly.
- We have included the specified insulation package.
- We have included all required flashing.
- We have included roof-edge metal.
- We have included required drainage interfaces.
- We have identified every exclusion.
- We have identified every allowance.
- We have identified every alternate.
- We have included required inspections and testing.
- We have included manufacturer warranty requirements.
- We have included closeout documentation.
- We have identified all assumptions involving other trades.
- We have identified schedule limitations.
Getting these answers in writing makes the final comparison much more reliable.
15. A good bid is the one with the clearest risk allocation
The best commercial roofing proposal is not necessarily the cheapest proposal. It is the proposal where the owner can clearly determine:
- What the contractor will install
- What materials will be used
- What work is included
- What work is excluded
- What is carried as an allowance
- What is offered as an alternate
- Who handles each trade interface
- What warranty is provided
- What inspections are included
- When the work will be completed
- What documentation will be delivered
Clarity reduces the likelihood that an apparently inexpensive bid turns into change orders during construction.
Bottom Line
Owners should evaluate new-commercial-building roofing bids using a scope-first, risk-adjusted comparison. Start by leveling the base scope, then identify exclusions, allowances, alternates, trade interfaces, warranties, inspections, schedule assumptions and closeout requirements. Only after those items are normalized should the owner compare the final prices.
The most reliable bid is the one that provides the clearest definition of the roof system and the fewest unresolved responsibilities—not necessarily the one with the lowest initial number.
Related Questions
- What roofing submittals should a GC expect from a commercial roofing subcontractor?
- How does roofing sequencing affect the overall commercial construction schedule?
- How should a GC evaluate roofing value-engineering proposals without increasing water-intrusion risk?
- What does a GC need to know about manufacturer warranty inspections on a new commercial roof?
- How do Florida wind-uplift and product-approval requirements affect commercial roofing bids and submittals?
Sources
- NRCA — Selecting a Contractor
- NRCA — Roofing Project Submittal and Protocol Guidelines
- NRCA — Contract Provisions
- NRCA — Specification Language for Building Owners
Last reviewed: October 2026
Related Resources
- What Roofing Submittals Should a GC Expect From a Commercial Roofing Subcontractor?
- How Does Roofing Sequencing Affect the Overall Commercial Construction Schedule?
- What Does a GC Need to Know About Manufacturer Warranty Inspections on a New Commercial Roof?
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Disclaimer: This information is provided for general educational purposes and should not be considered legal, engineering, code-compliance, procurement, or other professional advice. Project-specific roofing bids should be evaluated against the actual construction documents, specifications, approved assemblies, contract requirements, and applicable jurisdictional requirements.
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