Politecnico di Torino - Corso Duca degli Abruzzi, 24 - 10129 Torino, ITALY

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Solution to lighten a green roof

cropsExpanded polystyreneGreen roofModular lightening elementsStratigraphy


This utility model consists of an element of high-density polystyrene (expanded polystyrene) to be used in the cultivation substrate of the green roofs. The modular elements used for lightening the green roof are incorporated into the growing substrate and are not visible. They can be of different thickness depending on the lightening to be achieved.

Technical features

This utility model consists of modular elements of adaptable thickness, imprint  and shape, to be assembled for the creation of the soil layer, in order to reduce the weight of the green roof in relation to the bearable weights of the supporting structure in respect of the normal vegetative growth of some plants. This application allows to solve the problem of the weight of green roofs, without affecting the hydraulic and vegetative performance, maintenance and management of the system. The use of polystyrene elements is calibrated to occupy the part of the soil exceeding the quantity strictly necessary for the life and development of the plants. It also provides a surplus to thermal performance by enhancing the insulating performance of the entire package. Finally, the lightening elements can house pipes for the irrigation, sub-irrigation and fertigation systems.

Possible Applications

  • During the creation of the stratigraphy of the green roofs, to make the weight of the “green roof” package less burdensome by substituting part of the thickness of the ground;
  • Green roof systems in Mediterranean climate;
  • Sustainable urban hydraulics.


  • The innovative aspect of this model is the optimization of the use of the land: the use of the elements in polystyrene is calibrated to occupy the part of land exceeding the amount strictly necessary for the life and development of the plants;
  • Optimization of land use.