Gr01 is a design detail for insulation for a warm deck green roof with a single ply membrane. The roof is insulated using Knauf Insulations Polyfoam Roofboard Extra, which is an extruded polystyrene insulation slab.

Any type of roof deck can typically be designed as a green or garden roof, provided the roof structure is capable of carrying the associated loads.

The waterproofing is installed above the insulation to create a warm deck. The waterproofing layer is then covered with moisture reservoirs (and in some cases, root barriers). These are then overlaid with a filtration membrane, and planting to create a green or garden roof.

The vapour control layer should be laid over the structural deck and all joints lapped and bonded. The insulation boards are then laid in a staggered pattern from one corner of the roof.

Compression resistance: Polyfoam Roofboard Extra has a minimum compressive strength of 350 kPa. A factor of safety of 5 should be applied to the compressive strength of the products for long term static loads.

Thermal performance: Polyfoam Roofboard Extra up to 120mm thick has a thermal conductivity of 0.029 W/mK, and 0.031 W/mK above this.

Fire performance: when Polyfoam Roofboard Extra is installed in a green roof it will not contribute to the development stages of a fire.

Key data

Format	Slabs
K value (W/mK)	0.031
Material	Polystyrene