Summer '22
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GREEN ROOFS SPEC ADVICE<br />
GETTING THE SPECIFICATION RIGHT<br />
Nick Day, Managing Director of green roof specialist Optigrun, discusses the importance of<br />
selecting the right products when implementing green roof systems.<br />
The benefits of green roofs are<br />
now widely recognised, and they<br />
are becoming a familiar inclusion<br />
on building developments, with the<br />
requirements of specifiers when it comes<br />
to roof greening increasingly varied.<br />
As with other parts of the building<br />
fabric, it is important for the green roof<br />
specification to be correct to ensure<br />
long-term performance. Whether the<br />
goal is to increase biodiversity, manage<br />
rainfall or improve air quality, it’s<br />
important to select the right products<br />
and systems and to remember that<br />
there’s no “one size fits all” when it<br />
comes to green roofs.<br />
This article examines some areas of<br />
the green roof build-up where correct<br />
product selection is vitally important so<br />
that subsequent performance<br />
issues can be avoided.<br />
System approach<br />
At Optigrun we have<br />
nearly 50 years’<br />
worth of experience<br />
developing green roof<br />
products and systems,<br />
and regularly advise<br />
specifiers and contractors<br />
regarding specification and roof<br />
design. We have found that the system<br />
approach to product choice works best<br />
using a combination of layers that have<br />
been developed and tested to work<br />
together in the same way that the<br />
waterproofing and insulation system<br />
beneath the green roof will have been.<br />
The green roof system chosen needs<br />
Left: Nick Day, MD at Optigrun.<br />
to reflect the type of<br />
vegetation that will be<br />
required, the level of<br />
water storage required<br />
and the type of use that<br />
the roof will receive.<br />
Within each green roof<br />
system there are key<br />
product areas that need to be<br />
considered.<br />
Drainage layers<br />
Every vegetated green roof needs a<br />
reservoir function to store water for<br />
irrigation purposes during extended<br />
dry periods, but also good drainage.<br />
Poor drainage provision can risk<br />
waterlogging of the substrate layer with<br />
Left: Illustration shows a green roof<br />
build-up. Below: Illustration shows an<br />
Optigrun green roof layout. All images<br />
courtesy of Optigrun Ltd.<br />
20 GREENSCAPE SUMMER 2022 • www.greenscapemag.co.uk
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