A warm roof has its insulation on top of the roof structure, above the deck or rafters, so the timbers stay inside the heated space. This keeps them warm and dry, removes the need for a ventilated void and is the standard way to insulate flat roofs and many solid conservatory roofs.
How is a warm roof built?
- Roof structure and deck
- Vapour control layer on the warm side
- Rigid insulation boards, commonly PIR
- Waterproof membrane or roof covering on top
How thick is the insulation?
It depends on the board type and the target U-value. As one manufacturer example, around 120 mm of PIR board on a plywood deck reaches 0.18 W/m²K. A renovated roof element is generally expected to reach about 0.16 W/m²K.
What are the downsides of a warm roof?
- It raises the roof height, which matters at doors and fascias
- It depends on an unbroken vapour control layer and good airtightness, otherwise condensation can build up inside the insulation
- It usually costs more than insulating between joists
Wednesfield Trade Windows is a family-run, Certass registered installer, and the survey confirms what needs sign-off on your property. See our warm roofs for more detail.
Thinking about a warm roof? We supply and fit warm roofs across Wolverhampton and the surrounding area, and you deal directly with us, the owners. Call 01902 633355, message us on WhatsApp, or request a quote.