When considering which type of green roof to install, you first of all need to consider the physical and technical characteristics of your building. The maximum installation height and the maximum load of the roof structure will determine the thickness of the substrate and, thereby, the choice of vegetation.

The latter also depends on the roof’s orientation and on the level of maintenance you are looking for.

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intensive green roofs

Wouldn’t it be wonderful to turn your roof into a real living area ?
This is perfectly feasible. Indeed, unlike extensive green roofs, intensive green roofs are meant to be walked upon. In fact, you can use them for various recreative purposes.
An intensive green roof requires maintenance similar to the maintenance of a traditional garden. Of course, the building’s design needs to cater for the thick substrate layer.
But, then, the “land” used for your garden comes for free. A big saving, bearing in mind the high and ever increasing price of land.
De Boer Green has developed two standard systems for intensive vegetation. We can easily adjust them to your project’s specific requirements.

Semi-intensive green roofs

Although this “light roof garden” does not have a very thick substrate layer, it does offer lots of possibilities to create an aesthetic unity.
By opting for a semi-intensive system, you combine the benefits of extensive green roofs and the benefits of intensive green roofs:

  • a wider range of plants can be used (ground cover plants and ornamental grasses);
  • accessible;
  • requires little maintenance;
  • less structural demands than with intensive systems.

Regular irrigation is, of course, needed. Our range comprises species and varieties which are adapted to the specific environment of your roof:

  • ornamental grasses: Festuca spp., Penisetum spp, Imperata spp., … ;
  • ground cover: Vinca spp., Hedera spp, Pachysandra spp., …

Extensive green roofs

These low-maintenance vegetation systems are suited for (low pitch) roofs (1-35°) with a normal exposure to the sun, rain and wind and which are seldom walked upon.


  • requires little maintenance;
  • limited choice of vegetation;
  • not meant to be walked upon, except for maintenance;
  • the least demanding from a building-technical perspective.

Functional characteristics

  • aesthetic: permanent vegetation, which changes with the seasons and with the sunlight;
  • florescence from May to August, depending on the species;
  • slow-growing plants, requiring little maintenance, pruning or mowing;
  • plants which resist well to drought: watering is not needed, unless just after planting or in the event of exceptional drought (longer than 6 weeks);
  • acts as a rain water buffer (depending on the system up to 34 liters per m² and 50 % of annual rainfall); in the case of heavy rain, less water goes into the sewage system, and the water that does, does so much slower;
  • protects the waterproofing membrane against UV rays, thus significantly increasing the membrane’s lifespan;
  • protects the building from the sun during Summer: this natural cooling reduces the energy consumption of the air-conditioning system;
  • retains the dust particles in the air;
  • insulates against air nose and contact noise (rain or hail);
  • enhances bio-diversity (birds, bees, butterflies,…);
  • maintenance is limited to removing unwanted vegetation, fertilising and, if needed, extra sowing. Once or twice per year, depending on how the vegetation develops.