Flat roof

Warm deck - conventional systems

Systems

Loadbearing layer

Heat Vapour

Fig. 7: Schematic drawing of building performance parameters

Protective layer Separating layer Waterproofing layer Thermal insulatior Vapour barrier Falls in this layer

Loadbearing layer

Protective layer Separating layer Waterproofing layer Thermal insulatior Vapour barrier Falls in this layer

Loadbearing layer

Fig. 8: Section through warm deck (synthetic roof covering)

Protective layer Separating layer Waterproofing layer Thermal insulation Vapour barrier Falls in this layer

Loadbearing layer

Fig. 8: Section through warm deck (synthetic roof covering)

Protective layer Separating layer Waterproofing layer Thermal insulation Vapour barrier Falls in this layer

Loadbearing layer

Fig. 9: Section through warm deck (bituminous roof covering)

The conventional warm deck is a single-skin roof which contains one each of the necessary functional layers (loadbearing, waterproofing, thermal i nsulation, possibly sound i nsulation for accessible roofs). Various functions can also be combined in one material layer, although the waterproofing is always placed above the thermal i nsulation. When selecting materials, ensure that the components are compatible with each other and the building performance values are correct (use tried-and-tested combinations of products). Warm decks have a seamless roof covering. To prevent damaging condensation it is vital to install a vapour barrier on the inside (warm side) of the thermal i nsulation above the i oadbearing layer. The vapour permeability resistance of this vapour barrier must be coordinated with the other layers of the roof construction. A layer of gravel, paving flags, road surfacing material or planting is suitable for protecting the waterproofing against the weather and mechanical damage. It is usually advisable to install a separating layer, e.g. fleece, between the waterproofing and this layer of protection. The necessary falls (min. 1.5%) can be produced in the loadbearing layer, in a layer specifically incorporated for this purpose or in the thermal insulation.

Warm deck (synthetic materials)

The waterproofing here is a single layer of synthetic roofing felt with torched or bonded overlapping joints. The resistance to ultraviolet radiation is generally limited and so a protective layer must be added.

Various rigid products can be used for the layer of i nsulation. However, care must be taken to ensure that they are compatible with the waterproofing. Polystyrene, for instance, must be separated from the synthetic roofing felt (migration of softener). On accessible roofs it is important to ensure that the compressive strength of the thermal insulation is adequate.

Warm deck (bituminous materials)

The waterproofing here consists mostly of two layers of polyester-based bitumen felt. The first layer is laid loose on the thermal i nsulation and all further layers are then fully bonded together. When using pure bitumen sheeting at least three layers are necessary.

Various rigid products can be used for the layer of i nsulation. On accessible roofs it is important to ensure that the compressive strength of the thermal i nsulation is adequate.

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