Roof-Top planting and grassing
A decision for a roof-top garden has to be made and communicated during the stage of designing. The architect has to take into account and include it into the overall concept of the building. The garden layout and project are important in that weight of soil and plants shall be considered. For already completed and old buildings a certified garden construction permit shall be obtained prior to beginning work on them.
Once the architectural and construction design have been completed, designing the park layout and public works shall be carried out by a certified landscape engineer. The design of the roof-top garden is made at this particular stage, bearing in mind its functional purpose, making a layout of different areas and nooks, planning carefully different plant species, pavement finishing, garden furniture and lighting.
Depending on the plant species to be made use of, two types of roof-top gardens are distinguished. The first is a type of roof-top gardens of limited access, not frequently used. Such gardens have a vegetation layer of about 20 cm, whereas plant species shall not require regular maintenance, endure sun heat and limited watering, relying mostly on precipitations. Such species include sedums, certain decorative grass species and Juniperus. Such kind of grassing is rather functional than having a decorative effect.
Roof-top gardens designed for a particular purpose are of more interest. These can include food establishment terraces, areas designed for social contacts, or, green nooks for relaxation. In such a case, planting and grassing activities shall include planting trees, shrubs, seasonal and perennial species. The soil layer shall be of considerable thickness, about 70-80 cm. It is of particular importance to coordinate the project with the building designer and engineer to determine appropriate tree-planting areas.