Climate adjustment at roof height

roof water rainRoof Garden. Photo:

Climate adjustment at roof height

In densely populated areas, the roof becomes an increasingly important climate measure.


– When you build houses, you should think roofs that delay rainwater, says researcher Berit Time.

There is rain – extreme rain – which will give the biggest problems in Norway until 2100, shows climate research. In densely populated areas, the management of overwater and roof water, is particularly important.

– We must be ready for large amounts of precipitation in a short period of time. roofs can help to delay rainwater and thus be an important climate measure, says research scientist Berit Time at SINTEF to NTB.

Lead water in pipes

For a long time, it has been decided to lead the tide in pipes down into the ground and away from the building mass, as a measure to prevent moisture and flooding of houses. This is not unproblematic, especially in urban areas where it is built close and where green surfaces are lost under the constructions.

Time is Head of Climate 2015, which is the Center for Research-Driven Innovation (SFI), with its main base in Trondheim. She says that the traditional method of overwater management has had two major challenges connected to climate change: there will be more extreme rainfall that overloads the water and wastewater networks in a short period of time. In addition, the densification in urban areas has before the rainwater has fewer natural areas for drainage. The water simply has no place to do.

– Extreme rainfall can quickly overload the water and drainage networks, and the municipalities need to put restrictions on how much water can enter the municipal watercourse network, says Time.

Roofs more important

When looking for ways to solve the problem of overwater, roofs should be given more attention, she believes.

At SFI, three different roof solutions have been set up to look at the effect of rainy weather: Roofs made of Leca pellets, green roofs (sedum roof) and normal roofing.

– Concrete pellets are one of several materials that is suitable for storing water, says Time.

Finely crushed Leca can be laid in wide joints between tiles so that the water is filtered through. It is suitable for flat roofs, which can also be used as outdoor spaces.

Time believes that all new buildings should be planned with regard to the role that the roof can play in overwater management, but she believes that old houses can also get climate-friendly roofs. This may however include reinforcing of the roof structure.

– Sloping roofs will not be as effective, she says.

Measures on the ground

Nevertheless, so-called delay roofs must be used in conjunction with other measures on the ground, where there need to be surfaces that filter the water. A dense surface, such as asphalt, is the worst.

– Green ground level solutions also provide a cozy living environment, says Time.

She believes that the construction industry has gained a greater degree of awareness about climate adaptation, and that the industry has acquired a lot of new knowledge.

– But there are many players, and although construction industry is on its way, it’s still a long way before it’s being built for the far wetter climate we have in store, says Time.


© NTB Scanpix / Norway Today