Living roofs: a trend that is set to grow

IT may give a home a distinctly Hobbity look, but vegetation-covered houses are increasingly being seen in futuristic eco developments with ‘living roofs.’
A living roof involves covering the building with a waterproof membrane, into which plants are set, usually species that require little maintenance (they are on a roof, after all) such as mosses.
It’s a centuries-old tradition in some parts of the world, sod roofs having always been common in Scandinavia, for example, which has been adapted with modern materials in response to 21st century problems. In Germany, about 10 per cent of roofs have been turned into gardens, and the idea is spreading.
The environmental benefits are numerous. Living roofs provide excellent insulation, and can significantly reduce carbon footprint and the cost of heating the building, as well as extending the lifespan of the roof by up to 200 per cent.
And for the wider community, they promote biodiversity, providing urban habitats for birds and insects, help filter pollutants and store rainwater, easing pressure on drainage systems in heavy rain.
There’s even evidence that living roofs can make cities cooler in summer. Traditional building materials soak up radiation from the sun then release it as heat, which can see urban temperatures as much as four degrees Celsius higher than surrounding areas. After Chicago’s City Hall was given a green roof, temperatures on summer days were found to be between 1.4 and 4.4 degrees Celsius cooler than on other nearby buildings.
If that wasn’t enough reason to get roof planting, they could also make people happier and healthier. When the roof of a Stuttgart post office was ‘greened,’ a survey found that the number of staff sick days fell.
Spain hasn’t been as quick on the uptake of this environmental advance as Germany or other front-runners, but living roofs have been installed on some buildings here since the 1990s.
In fact, one of the biggest living roof projects tops Banco Santander’s headquarters in the outskirts of Madrid, with more than 100,000 square metres of roof garden.
And in 2013, the city of Girona tried the idea out on a bus, where the mobile roof garden cheered up passers-by, and cooled the bus enough to switch off the air conditioning.
Although initial outlay in installing a living roof is higher than building a boring old normal roof, the benefits seem so significant this is surely a feature of modern property that is going to grow and grow.