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Frequently asked questions?


What is the Green Roof Centre?

The Green Roof Centre is an independent research and demonstration hub, which supports and promotes the uptake of green roofs through demonstrating their benefits and potential in a wide range of settings and scales.
Founded by the University of Sheffield and Groundwork Sheffield, and based in South Yorkshire, the Green Roof Centre operates with partners in the region to demonstrate the potential of green roof uptake in the UK by focusing on the following areas of activity:
Research : providing rigorous and high-quality data on green roof performance across the range of environmental benefits, based on experimental green roofs, and real installations across South Yorkshire. Demonstration : the Demonstration Centre lies at the core of the Green Roof Centre, and includes examples of the main green roof types, full information on green roof construction and components, a mini-research station showing real-time performance, and inspiring examples of roof gardens and green roof planting options.
Information, Education and Training : the centre provides a central information point and resource for those interested in all aspects of green roof benefits, design, implementation and maintenance.
Policy and Development : working with local authorities, developers and agencies in the region to create a favourable climate for green roof and other sustainable building technologies.
Consultancy : providing advice and support on all aspects of green roof design and implementation.

How much does a Green Roof cost?

As with any construction process, cost is dependant on specification. There are many variants which need to be considered when specifying a green roof. However, indicative costs are between £60 and £100 per m2 for extensive roofs and £100 to £140 per m2 for semi intensive and intensive roofs. For further advice on what needs to be considered and therefore what the cost will include, please contact us to find out.

Do Green Roofs leak?

No, a Green Roof will not cause leaks, only poor installation or incorrect specification of the 'standard' roofing materials will result in leaks on new builds. When retro fitting a Green Roof on an existing building extreme care must be taken not to damage the existing roofing material. However, as with a new build, the Green Roof itself will not cause leaking if all other materials are fit for purpose.

Do the plants roots grow into the original roofs?

It is important to include a root resistant layer in the build up of the Green Roof system. Roofing manufacturers sell specialist materials for commercial building and pond liner material is more than satisfactory for DIY installers.

How do Green Roofs affect the life span of a roof?

A roof life is at least doubled with the addition of a green roof, thereby reducing the need to replace or repair the roof.

How do Green Roofs affect water drainage from the roof?

Research from around the world indicates that Green Roofs reduce annual run-off from roofs by at least 50%, and more usually by 60-70% - contributing to urban drainage and flood alleviation schemes. Moreover, the rate of release following heavy rainfall is slowed, reducing the problems associated with storm surges. With an increasing need for developments to have limited water run off, the Environment Agency now highlight the use of green roofing in their May 2003 publication “Sustainable Drainage Systems (SUDS) – an introduction.”

How do Green Roofs affect the buildings they are on?

Green Roofs reduce the temperature inside the buildings they are on during the increasingly hot summer months. The UK currently spend more money (uses more energy) cooling buildings in the summer, than heating them in the winter. Green Roofs reduce the need for air conditioning in the summer and as a result reduce CO2 emissions and keep a building cool.

How do Green Roofs affect wildlife?

New developments lead to a loss of habitats – green roofs can contribute to biodiversity and address local biodiversity action plans. In particular they have been shown to favour many rare invertebrates found on brownfield sites, as well as ground-nesting birds such as skylarks.

How do Green Roofs affect the quality of life for people?

Green roofs contribute to a greener urban environment and quality of life for communities in high density developments.

Does a Green Roof need planning permission?

It is always advisable to contact your local planning department and explain what you are aiming to do, especially if it is on a permanent structure such as an office, dwelling or garage. They will then advise on what your next steps should be, they will also ask you to speak to Building Control, who will be interested in the technical nature of the installation i.e. building loading etc.

Do I need to consult a Structural Engineer?

It is always advisable to contact a Structural Engineer. However, if you have discussed the design with Building Control, and they are satisfied that the nature of the work does not require additional strengthening, it is your choice whether to ask a structural engineer or not.

Where can I buy seeds to build my own green roof?

Right here, we can supply seeds for DIY builders and small scale Green Roof developments. Our seeds are a specially blended recipe developed by Dr. Nigel Dunnett to give a range of plants which both look good and are perfectly suited to the rigors of being on roofs. Click here to order.

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