Record use and the existing arrangement
Describe whether the roof is accessible and what equipment or protection it carries. Gather information on layers, past repairs and visible damage. Note water appearance with its timing and location. The point where water is seen inside may differ from the point of entry. Ask what investigation will identify the relevant condition before the scope is fixed.
Define the complete system and preparation
Request a description of the support, preparation, waterproofing, insulation where relevant and surface protection. Compare actual installed systems rather than a membrane name alone. Discuss the treatment of damaged or retained layers. The suitable arrangement depends on the existing roof and use; this guide does not prescribe a construction detail for an individual roof.
Examine outlets, upstands and penetrations
Locate edges, thresholds, drainage points and supports for equipment. Ask how their junctions are included and which contractor carries them out. A quotation for the main area may leave important connections outside scope. Discuss access to outlets and servicing after the work rather than assuming every item will remain visible or reachable.
Coordinate work, protection and inspection
Agree how the building is protected while layers are opened and how other trades access the roof. Identify inspection points before protection or finish conceals the waterproofing. Retain the relevant records and photographs. If equipment is moved or added, have the effects on waterproofing and structure discussed before a separate installer makes an alteration.
Handover with an accessible maintenance plan
Compare the completed details with the agreed scope, keep product references and request the relevant check information. Discuss how to inspect and maintain the roof safely and who performs specialist work. Record reservations and corrections precisely. Do not treat a new surface appearance as proof that every drainage point and concealed junction is satisfactory.
Your preparation checklist
- Use and existing layers recorded.
- Support preparation defined.
- Full system compared.
- Outlets and junctions assigned.
- Protection and checks scheduled.
- Maintenance and records agreed.
Questions before you commit
Does comparing membrane prices compare the full roof work?
Include support preparation, junctions, insulation, protection and access to compare the complete scope.
Can an equipment installer alter the roof independently?
Coordinate the proposed change with the relevant waterproofing and structural responsibilities before work.
Sources and the scope of this guide
This English guide covers the same project need as its French counterpart, with an editorial explanation in English. It is not a professional survey or a translation of foreign rules to France. Check current official requirements and the documents applying to your building and contract.
French reference: France Rénov’ : isolation des toitures-terrasses
French reference: ADEME : tout savoir sur l’isolation du logement