Topic
Commercial roof repair: scoping work above a business
On a commercial building the roof problem and the business problem arrive together. This page covers the systems you are likely to meet, the questions that decide the scope, and how to compare proposals.
The short answer
Commercial low-slope roofs are usually membrane, modified bitumen, metal or coating systems, and they are repaired by area rather than by the piece. The scope depends on the membrane type, saturation of the insulation, drainage and access. Because the work affects tenants and operations, scheduling and protection are part of the scope, not an afterthought.
Systems you are likely to be dealing with
| System | Repair logic | Watch for |
|---|---|---|
| TPO / PVC single-ply | Welded patches and seam repairs | Weld quality; patch edges lifting |
| EPDM | Adhered patches and cover tape | Seam adhesion; shrinkage at terminations |
| Modified bitumen | Patches, re-laying a section | Granule loss; seam lifting; blistering |
| Built-up roofing | Local repair, coating, or recover | Layer delamination; saturation that is hard to see |
| Metal (low-slope) | Fasteners, seams, panel replacement | Thermal movement; fastener washers |
| Spray polyurethane foam with coating | Re-coating, local foam repair | Coating wear; blistering where moisture is trapped |
Most commercial repairs are quoted by area after an inspection, and the inspection should distinguish between a local defect and a moisture problem in the assembly. Those are different jobs at different prices.
Questions the inspection should answer
- What is the membrane, and how old is it?
- Where is the water entering, and where is it travelling?
- Is the insulation saturated? How was that checked — core cuts, moisture survey, or visual?
- Is there positive drainage, and where does ponding occur?
- Are penetrations, curbs and parapets detailed correctly?
- What is the condition of the deck and the structure?
- What access is available, and what protection is needed for the space below?
Protecting the business while the roof is open
- Agree working hours around deliveries, customers and shift patterns, in writing.
- Ask how the space below is protected from dust, water and debris.
- Ask what happens if it rains while the roof is open — who is responsible for temporary protection?
- Confirm what equipment will be on site and where it will be staged.
- Agree who can be on the roof, and how access is controlled.
Comparing commercial proposals
Two proposals for the same roof often differ in what they assume: one may price a patch, the other a recover; one includes insulation replacement, the other excludes it; one includes drainage improvements, the other does not. The totals are not comparable until the assumptions are.
- Require a written scope with quantities and material specifications.
- Require exclusions to be listed explicitly, especially saturation and decking.
- Ask what warranty applies to the repair, and what the manufacturer requires to keep it valid.
- Ask whether the proposal is a repair, a recover, or a replacement — and why that option.
Our quote comparison tool works for commercial proposals too: it compares what you type in and flags the scope differences.
What to ask a roofing professional
- What system is installed, and what is its condition?
- How did you establish whether the insulation is wet?
- Is this a repair, a recover or a replacement, and why?
- What are the exclusions, and what would they add?
- What warranty applies, and what does it require of the building owner?
Questions this page answers
Is a recover cheaper than a replacement?
Often, but it depends on the existing assembly, the local code requirements and whether the insulation is wet. A recover over saturated insulation traps the problem, so the cost comparison only makes sense once the condition is known.
Can a repair be done while the building is occupied?
Usually yes, with planning around hours, access and protection below. That planning should be in the written scope rather than agreed verbally on the day.
Sources
Accessed 2026-11-10. Listed as general references for the organisations behind the guidance on this page; the page itself is our own explanation.
- National Roofing Contractors Association — consumer and contractor resources — NRCASupports: Professional context on how roofing work is scoped and priced.
- Asphalt Roofing Manufacturers Association — residential roofing resources — ARMASupports: Reference material on shingle systems and residential roof components.
Occasional, and only when there is something worth sending. The checklist and worksheet resources are free on this site whether you subscribe or not.
This page is general guidance, not an inspection of your roof and not a quotation. Roof Repair Roof does not perform roofing work or dispatch contractors.