Compare flat-roof repair and replacement proposals by assembly

Ask each proposal to name the affected assembly

GAF's commercial roof design guide describes low-slope systems as assemblies that can include the structural deck, vapor retarder, insulation, cover board and roof membrane. Ask the provider to identify the roof area and the layers its inspection could evaluate, then state which layers the proposal removes, retains or adds.

Do not assume a surface symptom proves what is happening below it. Request the observations, photos and access limits behind the recommendation. If a provider cannot determine a concealed condition before work begins, ask how that uncertainty will be handled rather than turning an assumption into a fact.

Separate repair, recover and tear-off paths

Make one column for each proposed path. Record the work area, removals, retained materials, new layers, attachment method, edge and flashing work, disposal and exclusions. A repair price and a replacement price are not meaningful alternatives until you can see what each scope includes.

Ask what finding would cause the provider to recommend a different path after work starts. The answer should connect the finding to a written change process. The FTC recommends getting project details, materials, price and timing in writing and comparing estimates before deciding.

• Area and layers affected
• Materials removed and retained
• New assembly and attachment
• Exclusions and change trigger

Resolve drainage, penetrations and tie-ins

Ask each provider to describe observed drains, scuppers, edges, penetrations and transitions within the work area. For each one, record the existing condition the provider observed, the proposed work and anything excluded. This makes a drainage or flashing assumption visible before it becomes a dispute.

If the quote proposes tapered insulation, added drains or work at equipment curbs, ask for the intended result and who coordinates any other trade. Do not infer that a general membrane line includes every penetration or drainage correction.

Compare the exact warranty and handover

Request the exact product or system identifiers, installer obligations and written warranty or guarantee offered with that scope. Ask what components are covered, who issues the document, what is excluded and what maintenance or registration is required. Do not substitute a brand name for the terms of the actual document.

Define the closeout package: photos, product records, applicable permit or inspection records, warranty documents and unresolved items. Keep the inspection evidence, accepted scope and later changes together so the final assembly can be compared with what was approved.

Related guides

• Compare roofing estimates: a worksheet for your next call
• What to ask for in a roof inspection report
• Roofing warranties: compare the documents, not just the number of years