Roofs cover up to 40 per cent of our urban area space. Green roofs may thus be the key to managing surface water after heavy rain. Photo: Bergknapp AS

New guidelines for green roofs

More green roofs and facades will help to create more space for natural habitats in our urban environments. A new set of guidelines has been prepared for those of us looking to green our roofs.

As our climate becomes wetter and torrential rain events more common, it is important to remember that green roofs have an enormous capacity to manage surface water. And that’s not all! More green roofs and facades will help to create more space for natural habitats in our urban environments.

Researchers at SINTEF, together with Oslo municipality, have recently prepared a new set of guidelines for the introduction of green roofs. 

There already exist a number of standards and guidelines offering advice in this field, but these focus primarily on the structure of the roof vegetation. The new guidelines go further by providing information about how installed vegetation influences the carrying capacity of the roof structure. They can be used in connection with both flat and gently sloping roofs on a variety of different building types.

“We’re hoping that the guidelines will reduce the barriers people may have to the introduction of green roofs on existing buildings”, says Ingrid Marie Finstad, who is a Project Manager at Oslo municipality.

“They can be used by building owners and consultant engineers to investigate how green roofs can be installed without having to increase the structure’s carrying capacity”, she says.

Green roofs and major renovations

The guidelines will offer assistance to developers, among others, in calculating roof carrying capacities, as well as advice about structural adaptations, should these be necessary.

“In many cases, the installation of green roofs on existing buildings may be both relevant and desirable, especially in connection with major building renovation work or re-roofing projects. In such cases, it will be possible to make adaptations to an existing roof at the same time, not least because a green roof will involve increasing the height of the building”, says Senior Adviser Kristin Elvebakk at SINTEF.

The guidelines include a method for calculating and recording the carrying capacities of a roof and ancillary constructions. For example, they describe how to conduct straightforward preliminary surveys in order to assess whether a green roof represents a viable option.

Preparation of the guidelines (in Norwegian) has been financed using funds earmarked for climate change adaptation, granted by the Norwegian Environment Agency.