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Handbook for successful green roofs

Green roofs are a way to reduce the effects of climate change in urban areas. For those interested in green roofs, Grönatakhandboken is invaluable.

A good quality green roof slows the effect of rain on the storm water system, is able to lower the temperature in both the building itself and surroundings, and provides food for the insects so important to humanity. Collectively, green roofs contribute to necessary climate adaptation while also increasing biodiversity and providing an aesthetic value.

The simplest and most common green roof is the sedum roof, which is covered in leaf succulent plants of the Sedum genus. Brown roofs or ‘biodiverse roofs’ are somewhat more complex. The idea is to mimic a certain biotope, such as a wet meadow or wetland. Brown roofs are often different variants of sod roofs.

It is also possible for the roof to be used for cultivation or roof gardens can be built, which are akin to small parks high above the ground.
It is important that the roof environment is included in the planning of a new property right from the start.

“You have to know at an early stage what you want to do with the roof,” says Mårten Västerdal, Project Manager at RISE. “There must be an understanding between the property owner, the builder, the architect and the municipality.”
Many people see green roofs as competing with solar panels, but, according to Mårten Västerdal, they work very well in combination.

There must be an understanding between the property owner, the builder, the architect and the municipality

Facilitates work and ensures quality

RISE has led the project to compile Grönatakhandboken, which describes the entire process from planning and design to construction and maintenance. The handbook facilitates the work at all stages and ensures that high quality is maintained throughout the process.

“The book describes the construction itself, including waterproofing, insulation and concrete, as well as the various vegetation systems,” explains Västerdal. “It’s also important that maintenance is not neglected. All green roofs require a certain degree of attention and care.”

The book also addresses how fire safety regulations can be met and how protective measures can be implemented.

Collaboration on handbook

Grönatakhandboken is the product of a collaboration between several different parties, and RISE’s contributions included – in addition to project management – expertise in fire, solar cells and energy calculations. RISE also conducts tests on how the roof slows storm water run-off at different substrate depths.

“The substrate layer should not be too shallow,” says Västerdal. “For a sedum roof, 5-8 centimetres are required. Otherwise, there is a risk that the plants will dry out and that the entire vegetation layer will blow off.
“RISE has expertise in areas such as roof construction, fire safety and slowing storm water, so we are happy to assist roof system manufacturers with development testing and verification.”

More complex green roofs naturally require much thicker substrates than sedum roofs, and in the case of a roof garden, extensive requirements are imposed on the design and construction of the roof. Grönatakhandboken has been supplemented with a paper called Vedartad vegetation på gröna tak, which addresses the choice of suitable tree varieties and what to consider when planting trees on roofs.
 

Grönatakhandboken

Grönatakhandboken is divided into two parts that deal with everything from concrete floors and waterproofing layers to plant beds, vegetation and much more. It contains both detailed practical information and general knowledge and can thus be an asset for anyone who in any way works with green roofs.

https://gronatakhandboken.se/

Published: 2021-09-13
Mårten Västerdal

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Mårten Västerdal

Projektledare

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