Guidelines for installing the URSA® HYDRO expanded polystyrene and URSA® FOAM extruded polystyrene panels

Required tools and materials:
1. Expanded polystyrene panels URSA® HYDRO
2. Extruded polystyrene panels URSA® XPS N-III
3. Extruded polystyrene panels URSA® XPS N-V

In an inverted flat roof, water insulation is laid below thermal insulation made of extruded polystyrene panels. This pattern of layers protects the waterproof layer from temperature changes, UV radiation and mechanical damage. In addition, a vapour barrier is not required.

In an inverted flat roof, water flows off on several levels. A slight amount of water leaks at the joints of thermal insulation panels down to the waterproof level. The most water flows off down the top surface of the thermal insulation. During heavy rainfalls, water also flows down the surface of the gravel layer. A complex external drainage system requires a shield with openings that allow water to flow out of all the layers.

Guidelines for installing the URSA® HYDRO expanded polystyrene and URSA® FOAM extruded polystyrene panels:

Step 1
One layer of URSA® HYDRO expanded polystyrene and URSA® FOAM extruded polystyrene panels is laid on the waterproof layer with staggered joints of adjacent panels. The panels must lap tightly on all sides.

Step 2
The minimum flat roof slope is 2% to enable efficient water outflow.

Step 3
Potential leakage can be avoided by laying UV-resistant (geotextile) panels on the layer.

Step 4
A draining layer of 16/32mm gravel is laid on the geotextile layer. Its thickness (>= 5 cm) should be calculated taking into account the wind drawing force. Alternatively, concrete slabs, paving blocks etc. can be used instead of gravel.

Step 5
During storage and longer breaks in the installation process, URSA® HYDRO expanded polystyrene and URSA® FOAM extruded polystyrene panels must be protected from exposure to UV radiation and organic solvents.

Step 6
When building a green roof, follow your vendor’s recommendations.