A guide to creating a green roof system using Grufekit

This guide outlines  key steps to installing  a beautiful green roof with our easy to use Grufekits.

Installed correctly, a green roof not only looks great but provides many different benefits including water storage, decreasing flood risks and new habitat creation. Small scale green roof construction projects, like a green garage roof and green roof sheds, are easy to create. Just follow these simple steps:

1 Add a Waterproof/ Root-proof Membrane

  • In many cases, flat roofs and outbuildings will already have an asphalt or bitumen felt layer of waterproofing. Your green roof will require an additional waterproof layer which is also root resistant. Ideally, use a single sheet to cover the whole area.
  • We recommend EPDM fixed with a strong mastic sealant.

 

 

TIP: Mark outlets/penetrations before installing so they can be easily located and cut out at a later stage.

2 Consider green roof drainage

  • Excess water must always be able to escape from the roof. Drainage outlets should allow water to flow into the roof’s guttering.
  • Drainage is very important: the roof must not be overloaded, so keep outlets clear and use a layer of pebbles to avoid blockages. Pebbles can also be used at the roof edge for a neat finish.

3 If your roof doesn’t have a parapet or an up-stand, then add green roof edging in the form of our Aluminium GrufeGuard.

GrufeGuard requires no fixings and is simply laid on top of the protection fleece (supplied in your GrufeKit) we recommend using 100mm height GrufeGuard as standard.

4 Install your vegetation

Our easy to use kits contain everything you need to lay a beautiful green roof. Create a living ecosystem with the pre-established green roof trays made up of 100% recycled growing media. Simply choose the planting scheme you prefer.

About the plants

  • Sedum mix 8 -12 varieties of the evergreen alpine plants used to living in harsh elevated conditions. They require little maintenance and maintain coverage all year round. The flowers also attract a wide range of insect species in the summer months.

  • Brown Wildflower mix 20 – 30 varieties of wildflowers and meadow grasses which can survive in low nutrient substrates more colourful display.

 

  • Sedum & Wildflowers The meadow-flowers that have been adapted for green roof use traditionally grow on limestone and chalk soils. They will die back every Autumn but the sedum keeps the roof green and attractive all year round.

Tip: To reduce the need for watering as the plants establish, lay your green roof in the Spring or Autumn

4 Maintain

Once established, a green roof requires little or no maintenance. Simply make sure:

  • In dry seasons, and in the first year of planting, water the plants well to achieve a good coverage
  • After the first year, watering is only necessary during exceptionally dry conditions i.e. 6 or more weeks without rain
  • Ensure drain outlets and edges remain clear and free from vegetation

 

Tip: If you have a particularly steep slope roof pitch, plants located near the top of the roof will get less water and need extra watering during very dry conditions.

 

Frequently asked questions

Will a green roof suit the pitch of my roof?

  • We do not recommend building a green roof on a slope of over 10° without specialist advice
  • When constructing a green roof on a slope of under 2° or over 10°  there are potentially some extra design considerations

Can the existing structure take the extra weight of the green roof?

  • Simple lightweight green roofs weigh between 60-150 kg/m2 (13.0-30.0 lb/sq.ft)
  • If you are unsure of the loading your roof can take, consult an architect or structural engineer before you do anything else
  • When calculating the weight that the green roof will impose on the roof, you must also take into account the weight of the green roof when saturated with rain or snow
  • If the existing roof is unable to take the extra weight, you may be able to reinforce it using wooden supports

There's lot's more information on the Green Roof Guide website. If you're considering a new green roof installation, feel free to call our team on 0800 124 4431 or use the live chat and they will be more than happy to offer advice and guidance.