Green Roofs

Neighbourhoods Green

What are green roofs?

Green roofs are a way of permanently introducing vegetation to the roof of your building, making it pleasant to view and environmentally friendly. There are different types of green roofs and the one you install will depend on your preference, budget, and what you want to achieve.  

For example, accessible roof gardens will need to accommodate people walking on them, while others may be specific habitat areas designed to imitate a natural environment. Some roof gardens may simply be a covering of hardy plants that will provide a variety of environmental functions.    

Photo Courtesy of Dr. N. Dunnett.

Why have a green roof?

Green roofs have several benefits for housing providers, residents, and the environment. These include:

  • Protection from harsh weather therefore saving on replacement costs in the long term  
  • A significant reduction in immediate water runoff, making it a good defence against flash floods
  • Planting  will help remove pollutants from the air  and will capture CO2 Urban cooling and buildings insulated from extreme tempretures in the summer and winter
  • Effective sound barriers
  • Increased local wildlife populations 


Further recommendations

Maintenance considerations:

  • Usually needed twice a year to check drainage outlets aren’t blocked and there are no tree seedlings
  • More maintenance needed where green roofs are constantly in view or used as an amenity area with access
  • Safe access is an important issue for maintenance
  • Substrate layer should be at least 80mm deep to allow for water storage during dry spells
  • Cutting initial costs on maintenance can lead to expensive re-green roofing operations a few years down the line  

Affordability and installation:

  • Sedum matting is a relatively expensive option but may not offer as many advantages as others - consider theenvironmental needs of your area to help to select the best kind of green roof
  • Companies following FLL guidelines and the UK Green Roof Code are more likely to provide a reliable service
  • Roofs should safely be able to take 100kg/m2 - ‘lightweight’ alternatives are available but may require more irrigation and care during dry spells
  • Select a supplier that understands your priorities - it is a good idea to request references, if possible from a customer for a roof they installed 4-5 years ago


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