Extensive Green Roof System

Extensive green roofs are designed to be low maintenance lightweight systems with no general access.

Extensive green roof system.

There are two main forms of green roofs intensive and extensive. Extensive green roof an extensive green roof system is characterized of its vegetation ranging from sedums to small grasses herbs and flowering herbaceous plants which need little maintenance and no permanent irrigation system. An extensive garden roof assembly can be applied to flat roofs and sloping roofs with a pitch of up to 12 12 or 45 provided the appropriate measures are taken to cope with the shear forces and soil retention. The planting medium in extensive green roofs ranges from 1 6 to 6 inches deep and while deeper systems have been installed they are not favored as much as the shallower systems drought tolerant sedums succulent plants and grasses are the typical plants used since they are shallow rooted and use little water plant diversity on these roofs is kept low to simplify care and to be sure all plants have similar moisture requirements.

Vegetation growing in a shallow 3 to 6 inch layer of lightweight soil medium contained in a special assembly system over a waterproof membrane. The soil is usually not more than 5 deep and is sometimes contained by a tray system which provides a barrier to excessive growth protects the roof membrane and also interlocks the entire system together to prevent wind damage. As the name suggests this green roof system builds on a plant palette dominated by sedum species but includes various drought tolerant upright perennials. A green roof is an additional roof system on top of an existing roof made up of a layer of planted vegetation.

Extensive green roofs are generally made up of a very thin layer of soil or other planting medium with shallow root plants like sedum mosses and grasses. They fall into three main categories extensive intensive and semi intensive. Most of these projects like the academy s are standard extensive green roofs as now defined. Intensive roofs take more time to manage as they can hold up to 150 pounds of vegetation per square foot.

Extensive roofs are typically lightweight and can be installed over a variety of structures including metal roof decks. Typically they have thin layers of substrate the growing medium to keep depth and weight to a minimum. A green roof is a layer of vegetation planted over a waterproofing system that is installed on top of a flat or slightly sloped roof. The growing medium depth for an extensive green roof system is typically 6 inches or less.

Increased water retention and soil depth provide for a wider range of plant choices and a more dynamic visual effect.