Green Roofs a Hit in Britain
Forget traditional slates and tiles. Why not cover your roof with living, sprouting flowers instead? The idea may have been around since ancient times — think of the hanging gardens of Babylon — but green roofs are finally becoming mainstream in Britain, the latest manifestation of our growing interest in sustainable, ecological building.
Extensive green roofs — the most common type on both residential and commercial buildings in Britain — consist of a waterproof underlay, covered with soil or crushed stones, then coated with sedum mats or wild flowers. More wild meadow than croquet lawn, they aim to recreate the original footprint of the building beneath by using local soils and varieties of flowers. In summer they come to life, with colour-strewn patches interrupting the urban monotony of asphalt roofs and air conditioning units — although in winter the flowers do die back, revealing the soil underneath.
They also require very little maintenance: you may need to check for rubbish or unsightly weeds once a year, but you certainly won’t be hoiking a lawn mower up on to the roof in order to give it a trim. Alex Michaelis, an architect who created a sedum roof on his house in Ladbroke Grove, west London, in 2004, claims his requires “no maintenance whatsoever”.
On environmental performance, green roofs outstrip any other roofing material by a mile. They replace land lost through building and encourage biodiversity: Michaelis’s roof, for example, has become a haven for urban foxes. Such roofs also absorb water run-off: a 100mm-deep moss and sedum layer over a 50mm-deep gravel bed retains about 71% of the water that collects on it — an essential tool against flash-flooding.
Green roofs also provide insulation, keeping homes warm in the winter and cool in the summer, so shaving money off electricity bills. They can block out noise, too — a bonus in our traffic-riddled cities — and absorb air pollutants, dust and greenhouse gases.
A green roof can be installed on any building, so long as the structure can take the weight and the waterproofing layer is secure. The whole roofing process could take just a few days.
[Read the full article in the Sunday Times.]
