Conservatory Roof Replacement Calculator — Weight & Compliance

A polycarbonate roof weighs approximately 3 kg/m². It is the complete loaded warm-roof system that matters structurally, not the bare tile: a lightweight tiled system totals around 48 kg/m² (e.g. Metrotile 6 + battens 6 + plywood deck 10 + rafters 3 + insulation 3 + plasterboard 20, per the SupaLite/Metrotile Eurocode structural calc), and solid insulated panel systems sit in a similar 35–48 kg/m² band. The bare tile alone is only ~6–12 kg/m², but the full buildup adds roughly 40–45 kg/m² over polycarbonate — significant, and usually requiring a structural assessment of the conservatory frame, ring beam and foundations.

Yes. Replacing a glazed conservatory roof with a solid or tiled roof changes it from an exempt conservatory to a habitable extension. Building Regulations approval is required covering structure, thermal insulation (Part L), fire safety (Part B), ventilation (Part F) and electrical safety. The separating doors between conservatory and house can usually be removed.

It depends on the frame design and the weight increase. Many lightweight tile systems (e.g. Tapco/Metrotile) are designed to work with standard aluminium or PVCu conservatory frames. Heavier solid panels may require frame reinforcement, additional columns or foundation upgrades. A structural assessment is always required.

The roof must achieve a U-value of 0.15 W/m²K — the limiting standard for a roof as a new fabric element in an existing dwelling, per AD L Vol 1 2021 (incorporating the 2023 amendments) Table 4.2. This typically requires around 150mm or more of single-layer PIR (λ ≈ 0.022 W/mK), or a rafter plus over-rafter combination. Most proprietary solid roof systems have factory-fitted insulation that meets Part L. Internal finishing is usually plasterboard with a skim or decorative panels. A full layer-by-layer U-value calculation is needed for Building Control.

Yes, in most cases. Once the conservatory has a solid roof and meets Building Regulations as a habitable room, the separating doors can be removed as they are no longer needed for thermal separation. This is one of the main benefits of roof replacement — it creates usable space all year round.