August 2020

SIG Roofing
WHAT’S BEHIND THE GROWING
POPULARITY OF GREEN ROOFS?
As with many other sectors, the roofing industry is seeing a sizable shift in outlook on
safeguarding the environment. As a result, roofers and property owners alike are looking
at different ways to maximise the eco-credentials of properties. Below, Chris Page, Flat
Roofing Product Manager at SIG Roofing, explores the growing popularity of green
roofing systems.
Across construction generally there is an
increasing focus on greener building
methods and materials, so it’s no surprise
we are seeing rising interest in the use of green
roof systems.
The benefits of such a system are clear. Using
vegetation as the top-finishing layer of a roof
instead of more traditional materials, green roof
systems can afford a property extra insulation,
absorb rainwater, extend the lifespan of the
waterproofing by preventing degradation caused
by UV light and, in some cases, even create a
habitat for wildlife. What’s more, the systems can
be easily installed on new build projects or
retrofitted to existing roof coverings, when used in
conjunction with root-proof membranes and
allowing for the structure to accommodate
increased roof load in both cases.
When it comes to green roof systems, there are
three general technical descriptions which
describe the separate ways in which they can be
applied. They are Extensive, Intensive and
Biodiverse.
Extensive green roofs are the most common
type of green roofing systems, and are typically
used for single or multi-family residential
buildings. Extensive systems can also be fitted to
outbuildings such as sheds or garages.
Among the key benefits of such a system are
rainwater run-off attenuation and greater
insulation, alongside minimising the overall
increase in roof load that all green roofs will
present.
“If properly
installed and
well looked
over, they not
only deliver real
‘kerb appeal’, but
also bring home some
environmental and
financial benefits too”
Extensive roofs generally require little
maintenance once fully established, making it the
most economical system and perfect for use on
unseen or large-scale roofs. The vegetation
generally used on extensive green roofs are wind,
frost and drought resistant, enabling them to
survive in tough, harsh conditions at height and
typically covers 90-95% of the surface area upon
installation. This type of green roofing system is
suitable for all roof slopes with at least a
minimum achieved fall of 1:80.
Intensive green roofs, or ‘roof gardens’, are
generally designed to provide recreational space
for the building’s occupants. Intensive green roofs
consist of a deep layer of engineered growing
media, typically 150mm to 1500mm. As a result
of this soil depth, they may be landscaped to
include trees, lawns, flowerbeds, vegetable
patches and paved areas, and will need as much
care and maintenance as any garden.
Intensive green roofs require more maintenance
because of the plant varieties they support,
Left: Chris Page, SIG Roofing.
however, as the garden is in a
much higher elevation there
may be a significantly smaller
chance of attack by pests and
weeds. In addition, larger plants
typically need more growing medium
depth, which means the building’s structure will
have to be designed to take the additional weight.
Biodiverse (or brown roofs) are designed to
replicate the environment lost to building and
involves the creation of natural habitats for many
varieties of plants and birds. With an increasing
number of developments taking place on
brownfield land, the use of biodiverse roofs can
partly protect against the total loss of habitat on
those development sites. They provide the end
user with an opportunity to enhance planning
applications by meeting local environmental
concerns and provide improved BREEAM ratings.
At a time when environmental consciousness and
the push towards sustainability is greater than
ever before, green roofing systems offer many
obvious benefits to both the roofer and the end
user. If properly installed and well looked over,
they not only deliver real ‘kerb appeal’, but also
bring home some environmental and financial
benefits too.
Contact SIG Roofing
0845 612 4304
www.sigroofing.co.uk
@SIGRoofing
22 TC AUGUST 2020