The importance of the substrate layer of green roof systems has grown steadily over the past few years. The proportion of intensive green roofs is increasing year by year.
Special material is normally used to build up the different substrate layers (for support and nutrition) for roof-top plantings. Conventional soils would be too heavy. Substrates for green roofs are intricately mixed from specific constituents such as lava, expanded clay granules, bark humus, etc. Above all, the thickness and physical properties of the vegetation support layer play a decisive role in how well the plants used are supplied with nutrients and water. In other words, the quality of the substrate constituents plays a crucial role.
Gütegemeinschaft Substrate für Pflanzen e.V. monitors quality assurance also for substrates for green roofs. Right up until today, the most varied types of substrates have been developed for the specific uses (see overview of quality criteria), because each substrate has to meet different requirements.