A warm green roof, or warm garden roof, is a flat-roof construction in which the thermal insulation is installed below the waterproofing system, with the vegetated roof build-up positioned above it.
This configuration combines the principles of a warm roof with the functional layers required to support vegetation. Above the waterproofing system, the roof build-up incorporates the components required for root protection, drainage, water management, filtration, growing medium and vegetation, according to the selected green-roof system.
Rigid polyisocyanurate (PIR) insulation is particularly suitable for this type of warm-roof construction because it provides high thermal performance together with the mechanical characteristics required within the roof build-up.
For warm green roofs with compatible bituminous waterproofing systems, POLIISO® SB provides a dedicated PIR insulation solution. The panel features a bituminised glass-fibre upper facing and a saturated mineralised glass-fibre lower facing, with a compressive strength of ≥ 150 kPa and declared thermal conductivity λD from 0.025 to 0.028 W/mK depending on thickness.
The design of a green roof must take into account not only thermal and waterproofing performance, but also drainage, water management and the loads generated by the complete vegetated roof system.
