Obtain information for the complete system
Ask the supplier to describe every layer and the loading information for the intended conditions. Identify equipment, access routes and other features alongside vegetation and substrate. If combining a green roof with solar panels, submit both plans together. The combined arrangement may raise different issues from either system alone. Identify provisional product data so the design is not inadvertently based on incomplete information.
An existing roof has its own starting conditions
Gather structural drawings, the existing roof build-up and records of earlier alterations. Identify which old layers will be removed and which remain. The engineer can account for removed loads only if removal actually forms part of the proposal. Unknown member dimensions, supports or visible damage may require further investigation. A general statement that a roof is strong is not usable assessment information.
Record use and future changes
A vegetated roof is not automatically designed as an accessible terrace. Discuss its intended use and maintenance access. Temporary material storage during installation also requires coordination with the contractor and responsible adviser. Record the selected system and have later changes assessed, such as different layers or new heavy objects. Drainage and waterproofing must also be developed by the responsible parties.
Practical checklist
- Provide the complete layer build-up
- Request loading data including retained water
- Identify solar panels and other features
- Record intended use
A stated dry product weight is not a complete roof loading specification.
Preparing your own project
Would you like this assessed for your home? See our information about house extensions. It explains which information is relevant to that brief. The project check helps you prepare your enquiry.
Unsure about a term? The structural glossary provides plain-language explanations and technical context. To understand how the documents are organised, explore our fictional example project .
Background and sources
Sources checked on 3 October 2026. This guide is not a project-specific assessment.
Editorial guide • updated 3 October 2026. General information; not a project-specific assessment.