Design solutions: Green roofs
Green roofs help make our cities more healthy and beautiful and welcome wildlife into our gardens. Below are points to consider before creating a green roof including what is a green roof? Plant selection and how to build a green roof.
Creating your own roof garden means you will have a new green space to enjoy in your home. More importantly, it will effectively revive an area of natural landscape lost when the land on which your home lies was originally developed. Green roofs can become micro-environments rich in value to wildlife.
What is a green roof?
How to set up a green roof
Ask an expert
KEY POINTS TO TAKE AWAY
- Mats or rolls of sedum vegetation will need fertilising and watering in the first weeks after installation. After this they are relatively low in maintenance.
- On smaller roofs such as those of sheds, summer houses and so on, sedums can be individually planted into the roof substrate or mat. Normally densities of 15 to 20 plug plants per square metre are used. In this way one can achieve a tapestry effect, but the plants may take longer to establish – between 12 and 18 months. Pre-grown mats establish in a much shorter time period.
- In planted roof gardens, lightweight materials such as Leca (expanded clay granules) or even polystyrene should be used to bulk up unnecessary space in planters. Growing mediums should then be added on top.
- When using roof spaces that were not designed as gardens you should consult your local authority. They will take a view on balustrades, which should be introduced for the safety of garden users and of those down below.
- Consult a structural engineer if you are planning to use a roof space as a garden. They will be able to offer advice on the strength of the structure and its suitability for use as a garden.
Useful websites and publications
- www.bauder.co.uk Green roof systems. Producer of roof and planting systems for a variety of applications.
- www.grassroofcompany.co.uk Advice and inspiration, including a downloadable DIY guide to green roofs (£11.65), from a firm which won a silver gilt medal at Chelsea in 2007.
- www.livingroofs.org Advice on the installation of green roof systems and the philosophy behind them, from Mathew Frith and ‘urban ecologist’ Dusty Gedge (see also www.dustygedge.com).
- www.nigeldunnett.com Information on roof garden schemes undertaken by Dr Nigel Dunnett, with links to research by Nigel’s department at Sheffield University.
- Planting Green Roofs and Living Walls by Nigel Dunnett and Noël Kingsbury (Timber Press, 2008). Information on the construction and planting of green roof and green wall systems.
- Rain Gardens by Nigel Dunnett and Andy Clayden (Timber Press, 2007). How to channel, save and redeploy the rainwater that falls on your property.
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