Green Roofs

Green / Grass / Sedum Roofs - Marnick Roofing Cornwall's number 1 green roof fitter

green roof / grass roof / sedum roof is a roof of a building that is partially or completely covered with vegetation and a growing medium, planted over a waterproofing membrane. It may also include additional layers such as a root barrier and drainage and irrigation systems.

Green roofs serve several purposes for a building, such as absorbing water providing insulation, creating a habitat for wildlife and decreasing stress of the people around the roof by providing a more aesthetically pleasing landscape. They effectively utilise the natural functions of plants to filter water and treat air in urban and suburban landscapes. There are two types of green roof: intensive roofs, which are thicker, with a minimum depth of 12.8 cm and can support a wider variety of plants but are heavier and require more maintenance, and extensive roofs, which are shallow, ranging in depth from 2 cm to 12.7 cm lighter than intensive green roofs, and require minimal maintenance.

It is important to consider the appearance of the selected Green Roof system both in the short term & long term. Planting should be tailored to suit the desired end result.

Sometimes referred to as roof gardens, an intensive green roof can be as simplistic or as complex as the client requires. Generally speaking an intensive green roof requires the same level of care as any traditional garden.

Specifically selected to suit the final finish requirements of the client / end user. On Intensive green roofs a wide variety of vegetation can be used from grasses to shrubs and trees as well as hard surfacing such as pavers and block paving.

Intensive green roofs consist of a deep layer of engineered growing media, typically 150mm to 1500mm. As a result of this soil depth there is a greater scope of planting available and the roof can be viewed very much like a garden area and may be landscaped to include trees, lawns, flower beds and paved areas. With an intensive roof the only real limit to its scope is the weight of the system and the structure necessary to support it.

A wide variety of plants are suitable for green roof planting schemes; mosses, sedums and grasses for Extensive though to deeper rooted shrubs and trees and even fruit and vegetables for Intensive Roofs. The decision is entirely dependent on the roof  finish required.

The British Standards Institution state that all new builds must provide access to the roof area to enable a minimum of two inspections per year, so working at height regulations must be considered. If a building is of a height which can cause an injury from a fall, including roofs under 2m, then edge protection is required.

Even though extensive Green Roofs are relatively self-sustaining, they still require some form of maintenance. We recommend this should be dealt with in the form of a maintenance contract. Maintenance for extensive roofs will typically be required twice in the first 12 months, then once annually thereafter. Therefore the overall cost of maintaining a Green Roof can be relatively minimal.

As opposed to having a ‘one system fits all’ approach, our supply chain enables us to put forward bespoke systems to help meet the needs of the client, on time and within agreed budget.

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