This type of hot or traditional flat roof is obtained by applying the waterproofing on the insulating layer. In order to avoid hygrothermal problems, besides using a vapor barrier, a good drainage system is to be used to dispel water vapor.This type of roofing is used when creating roof gardens with any type of plant either for esthetic or environmental purposes.Garden roofs can pose hygrometric and static problems if special attention is not paid during the design phase. Good thermal insulation is essential.

Laying: a coating of lightweight mortar with a minimum gradient of 1% is applied on the roof's concrete slab.  A vapor barrier is laid on this coating following by the POLIISO^® SB expanded polyurethane insulation panels, which are applied trying to cover the entire roof surface. The insulation panels must be fastened to the hardcore with hot bitumen. A separating layer and waterproofing bituminous membrane are applied on the polyurethane panels. A root barrier membrane is applied to finish. If the drainage layer has particles with a diameter of less than 10 mm, a filter layer is to be applied to protect the waterproofing against abrasion by the drainage layer and soil. The roof is completed by applying an adequate layer of soil or humus on the drainage layer depending on the type of vegetation to be planted.