Extensive Green Roofs

What are the extensive green roofs

The extensive roof gardens are used on roofs with lower load rate roofs (50 - 300 kg per square meter). Low load rate allows us to use only shallow layer of vegetation substrate and only specific sorts of plants, that requires almost on maintenance (using plants too demanding on maintenance with this type of green roof could cause serious problems as when maintaining such roof garden the roof can get overloaded), such as ever green small alpine plants or succulents, that are able to survive extreme conditions, long periods of heat, cold or dry weather. Extensive green roofs usually are not irrigated.

Types of extensive green roofs (based on the thickness of vegetation layer)

Basically, there are 3 possible extensive roof garden types based on their begetation layer thickness: - layer thick 3 - 5 cm (covered with moss or pre-cultivated lawns); - layer thick 6 - 15 cm (alpine plants, lawns seeded right on the roof); - layer thick 16 - 20 cm (the above and some sorts of small bushes). The first type of green roof vegetation is not seeded on the roof but usually pre-planted in the garden. The pre-cultivated moss or lawn carpets are scrolled and put on roof when they reach approx 3 cm thickness (weigh 20 kg per square meter at that time). Vegetation substrate for the green roofs of the 2nd and 3rd type consists of light-weight composts, turfs and bentonite granules.