There is an increasing interest in sustainable and environmentally friendly entrepreneurship, which is not surprising in this era of climate change. With a green roof or green wall, you make a good as well as a beautiful contribution to the environment. It also offers many other benefits. For example, calculations have shown that a green roof already pays for itself after 4 or 5 years through a reduction in energy costs.

Structure of a green roof
A green roof consists of the following layers:

• Watertight and root-proof roofing of two or three layers
• Protective layer against mechanical damages to the roofing
• Drainage layer of, for example, plastic or minerals
• Filter layer
• Substrate layer
• Vegetation layer

Systems in which multiple layers are put together exist, such as the buffer drainage mat, which also has a protective function.

Applications

Sedum is widely applicable. Below are the options at a glance:

• Green roofing for flat and sloped roofs of (corporate) buildings, offices and homes.
• Green roofing for sheds, carports, additions, container boxes and animal quarters.
• As a ground cover, such as in the garden around ponds or water, in the middle part of driveways or tram tracks, and on roundabouts.

Conditions for the application of sedum

• The existing roofing must be waterproof and root resistant (if necessary, using a root-resistant filter fabric).
• Use of drainage mats, which creates good drainage rather than puddles.
• Sun or partial shade instead of shade.
• Roof system must be able to support at least 100 kg per m² (even after heavy rain).
• The roof has raised eaves of at least 10-12 centimeters; this prevents the substrate layer from shifting or from washing from the roof.

Benefits

The benefits of a green roof at a glance:

• Protects the roof construction and thereby extends the lifespan of your roof.
• A bitumen roof can heat up to 80ºC during hot summers and cool down to -20ºC during winters. This is a difference of up to 100ºC. With a green roof, the difference is no more than 35ºC, which results in less shrinkage and expansion.
• The roof is kept free of UV-radiation and there is less vapor effect. Calculations show that a green roof already pays for itself after 4 or 5 years through a reduction in energy costs.
• Rainwater is drained gradually, which prevents overload of the sewer system.
• It gives your (corporate) building or home a sustainable image.
• Easy application and maintenance.
• Sound absorbing.
• Suitable for roofs with a slope of 0 to 45º.

Extensive green roofs

‘Extensive green roofs’ is the collective name for sedum, moss, grass and herb roofs. The thickness of the green roof structure is no more than 15 cm and the height of the vegetation is no more than 50 cm. The vegetation develops into a more or less ecologically stable plant community that sustains itself with a minimum of maintenance.

Sedum roof
The vegetation consists of a smaller species of succulent plant in various colors that can be combined with moss. Sedum roofs are lightweight; a substrate layer of 4 cm is often sufficient.

Herb roof
Various combinations of grasses and herbs, often with a base of sedum. The roofing is relatively lightweight, depending on the composition.

Intensive green roofs

Intensive green roofs are roof gardens with a construction height of over 15 cm. The vegetation is characterized by the presence of bushes and trees, optionally in combination with a lawn and/or ground covers. In this form of roof vegetation, intensive maintenance is required, including watering, trimming, fertilizing and weeding.

Grass roof
A grass roof requires a soil of 15-20 cm on a flat roof and at least 20-25 cm on a sloped roof. A heavy roof structure is required. Grass roofs are no lawn roofs, even though they have the same vegetation. A grass roof is intended as roofing. If you want to use it as a roof garden and walk on it, a special roof construction is required and grass roof is categorized as intensive green roofs.