Applications
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Roof gardens - Application
According to the roof structure, various constructional and building physical conditions regarding the suitability and the effects of all layers and materials in the roof construction should be considered when making a roof garden.
1. Roof construction
The most popular options are a “warm roof” and a “reversed roof”. On a warm roof the insulation material is put on the construction, with a water-resistant layer on top. This type of roof garden is the most frequent one. It is even though important to guarantee that the waterproof membrane is protected against mechanical damage. For a reversed roof the insulation material is put on the waterproof layer. The drainage layer and the substrate are put on top. Like this the insulation sheets (mostly XPS) are kept in place. The advantage of this system is its simplicity (no additional vapour screens required), but the greater thickness of the insulation layer should be considered (more heat loss in corners and on sides + insulation if in contact with moisture). On top of the roof membrane the Argex roof garden is further developed such as described in the scheme below. The used insulation material should have a sufficient pressure strength. We refer to the Butgb-ATG requirements for insulation on roofs accessible for frequent pedestrian use.
- Load-bearing structure and slope
- Vapour screen
- Insulation material
- Waterproof layer
- Mechanical protective layer and/or polythene sheet
- Argex drainage layer
- Filtration mat
- Substrate
- Vegetation
2. Roof-slope
- The flat roof should have an adequate slope of at least 2%, according to the building instructions for flat roofs.
- In case of intensive roof gardens a constant water level can be chosen (please also consult the local legislation on this subject). Hereby, no slope is required or one can use dam sills in the other case. The constant water level allows permanent water reserves that are equally divided over the entire surface.
- With extensive planting moisture accumulation in the substrate (e.g. through pool forming or around the water outlet) should be prevented. This accumulation damages the vegetation badly.
- In case of larger slopes measures should be taken to avoid the slipping and sliding of materials. Therefore a substrate with ‘water-stable’ structure should be used, but also sliding profiles and/or anti-shifting textures.
