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Brief History
 The original inspiration
for contemporary green roofs came from rugged Iceland, where sod roofs and
walls have been used for hundreds of years. The sod roofs soon became popular
throughout Scandinavia. The Icelandic architectural style originated because
of a lack of natural resources. People had to make do with the local materials
of sod and stone. Roofs topped with soil and a layer of vegetation have
been used throughout history all over Europe, as well as, by ancient tribes
in America. Early settlers in Americas Western prairies took advantage of
the technique, creating shelters with readily available materials. An updated
variation of this system has become enormously popular again in Europe.
From its birth in the 1960s the green movement has grown slowly. As its
principles have merged with the capitalist system and technology has made
improvements in materials and techniques, green building has become an important
environmental issue. Modern green roof technology originated in Germany
over 30 years ago, and is quite popular throughout Europe mainly due to
its positive environmental impact.
The modern system uses a membrane to provide waterproofing and a root barrier,
while the vegetation absorbs rainwater, provides insulating properties and
protects against mechanical damage. This innovation is hundreds of years
old but through the use of modern materials has become contemporary again.
Green roof systems provide the perfect union of Aesthetics, Economics and
Ecology.
Green roofing systems may consist of a liquid-applied membrane or a specially
designed sheet membrane. Many of the oldest green roofs are waterproofed
with mastic asphalt but bitumen sheets with polyester carriers and SBS modified
coatings are becoming more common. In the early 1990s PVC and EPDM products
were developed. Root resistance is achieved either by a laminated upper
layer (usually copper) or by chemical additives in the coating. To ensure
drainage capacity the support to the waterproofing layer should have a slope
of at least 1.5%.
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