Flat roof coating or repair: what does your roof need?
A coating proposal should explain why the existing roof is a suitable surface to coat. Do not treat a new white finish as proof that leaks, drainage or underlying damage have been resolved. Request an assessment before choosing between a recoat, targeted repair and replacement.
| Proposed work | What the scope needs to explain |
|---|---|
| Protective recoat | The existing system, product compatibility and preparation |
| Localized repair | The defect being addressed and the limits of the repair area |
| Drainage correction | The cause of retained water and the proposed correction |
| Replacement | Why retaining the existing assembly is not appropriate |
Start with drainage, not coating color
Water remaining on a low-slope roof deserves an explanation. Gaco describes several possible causes of ponding, including drainage obstructions, roof geometry and deflection. It recommends correcting inadequate slope before coating and checking adhesion for compatibility. See Gaco’s ponding-water guidance.
Ask for photographs that locate the affected area and the drainage route. If the contractor suspects a structural issue, ask whether a qualified structural professional must evaluate it. A coating specification should not stand in for that assessment.
Do not climb up to inspect standing water or clear drains yourself. Provide any dated photographs and maintenance reports you already have, and arrange professional access.
Identify the roof that is already there
“Flat roof” describes a shape, not a single material. Before comparing prices, ask the contractor to identify the existing assembly and any prior coatings or repairs. Give them records from previous roofing and rooftop equipment work.
Have the proposal answer three questions: what is being retained, what needs removal or repair first, and what evidence supports that decision? If the existing layers cannot yet be identified, the quote should state what further investigation is needed.
What should a coating specification include?
Use this checklist to compare proposals without trying to design the roof yourself:
- Named system: Manufacturer, product and the roof surface it is intended to cover.
- Preparation: Cleaning, repairs and any primer or adhesion testing required by that system.
- Detail work: Separate treatment of seams, penetrations, wall connections and drainage openings.
- Application requirements: Specified coverage or film thickness, how it will be checked, and relevant weather limitations.
- Occupied-building coordination: Access, protection of nearby surfaces and coordination with equipment service providers.
- Closeout: Product records, completion photographs, warranty terms and a maintenance plan.
Ask for the manufacturer’s current instructions with the proposal. Do not compare two bids only by the number of coats; have each contractor explain how their proposed application meets the specified system.
Questions about recoating a flat roof
Can a coating fix an active leak?
The proposal should identify the leak source and the repair that addresses it, even when coating is part of the work. Ask what remains uncertain and how the completed repair will be checked. “Coat the roof” alone does not define a diagnostic or repair scope.
Are silicone and acrylic interchangeable?
Do not assume so. Gaco describes its acrylic coatings as an option where ponding is not an issue, while its GacoRoof silicone product lists ponding-water resistance. Those are product-specific statements, not permission to ignore drainage or apply any coating to any roof.
How often should the roof be recoated?
Ask for a schedule tied to the installed product, warranty and observed condition. Keep inspection and repair records so the next recommendation can refer to the actual roof rather than an assumed universal interval.
See commercial roof assessments and maintenance or roof repair services. For competing scopes, use the inspection and bid-comparison kit.