Green roof

A green roof is a roof whose surface is covered in planting, supported by a purpose-built layered system. It benefits both the building and the city: it holds rainwater and releases it slowly, keeps the roof surface from overheating, shields the waterproofing from sunlight and offers habitat for birds and insects. Most green roofs are on flat roofs, though gently pitched roofs can take them too.

Extensive and intensive green roofs

Green roofs usually fall into two groups. Extensive roofs use a thin growing layer planted with drought-tolerant, low-maintenance species such as sedum; they are light and not meant to be walked on. Intensive roofs have a deeper soil layer that can carry lawns, shrubs and even small trees; they are true roof gardens but much heavier, and need irrigation and regular care. The build-up is similar in both: waterproofing, root barrier, protection fleece, drainage board, filter layer and growing medium. Designing the structure for the weight of saturated soil and making sure the membrane is root-resistant are the fundamentals.

Green roofs in visualization

In aerial views, a green roof explains a project’s environmental approach at a glance. Thinking about the relationship between green spaces and architecture, varied species and a natural-looking distribution are what separate a convincing render from a flat green carpet.