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Very common in the Scandinavian countries and Japan, green roofs are an asset for the environment. Beyond the ecological aspect offered by this alternative to conventional roofs, green roofs are also resistant and insulating.

A green roof is composed of a mixture of rooted herbaceous plants. A protective layer is necessary between the frame and the plant part to prevent mold. In addition, the frame must be solid, because this installation is very heavy.

There are 3 types of green roofs: extensive revegetation, semi-intensive revegetation and intensive revegetation. The first (which is the most complex) is to create a real ecosystem on the roof. The second, the simplest to put in place, is more decorative and requires little maintenance. Finally, the last type is the one that requires the strongest frame, able to support up to 350Kg / m2, because we approach the hanging garden.

Advantages and disadvantages of a green roof


  • A green roof is aesthetic, it gives originality to any house. In addition, it will bring greenery to the surrounding urban space, a phenomenon that makes a city more pleasant to live!
  • The green roof provides better insulation to your home, compared to tiles or slates. This advantage has an ecological and economical scope, because you will need less to heat your house. The improvement of the insulation is not only thermal, it is also phonic!
  • This type of roof protects you from the risk of flooding: rainwater is better retained and evacuated by evaporation.

The inconvenients:

  • A green roof may require some maintenance: in hot weather, it is necessary to regularly water the plants.
  • The addition of a growing medium and plants should be done on a particularly solid roof and little leaning.
  • The design of this alternative roof requires the expertise of professionals. Thus, the price is, in general, 4 to 5 times higher than that of a conventional roof.

The establishment of a green roof

It is strongly recommended to use a company specialized in the field for the installation of a green roof. However, there are things to know before even setting up plants. If the plants chosen for rooftop installation are not precultured, it is necessary to provide 6 months to a year to see the final result. On the other hand, the installation of precultivated vegetable rolls will allow you to obtain a result immediately after the works. As for the choice of plants that will cover the roof, it is advisable to choose plants that are resistant to large temperature differences and a large amount of water.

The green roof is an ecological alternative to the classic roof. It is a privileged area in cities that will attract birds like bees. Expensive purchase, this type of roof is ultimately economical in terms of energy consumption.

Video Instruction: Do Cities Need More Green Roofs? | NPR