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 What is a green roof? Green
roofs are vegetated rooftops, or roofs covered with living plants. Like
any planted area, living roofs experience periods of growth, flowering,
and dormancy, and so they are sometimes referred to as living roofs.
Why install a green roof? Green
roofs offer an enormous range of benefits. The most commonly cited are:
stormwater mitigation, reduction of the Urban Heat Island Effect,
thermal efficiency and energy conservation, noise reduction,
aesthetics, improved air quality, and increased biodiversity.
What is the difference between extensive and intensive green roofs? An extensive green roof
uses a thin (8cm to 20cm) layer of substrate to create a carpet of
plants, often sedums and grasses. Extensive green roofs often occur on
structures that cannot support more than just shallow substrates, and
so these roofs are only minimally accessible to people. An intensive green roof
can support much greater depths of substrate, and therefore much larger
plants. Depending on the building's structural capacity, an intensive
green roof can support features that might be found in ground-level
gardens, like trees and stone garden planters. These areas tend to be
designed for public use.
If the plants are suitable for the roofscape, why is at least one year of maintenance recommended? Whether
at grade or on the roof, most plants show better long-term performance
if they've had the benefit of proper establishment. Installing some
method of emergency irrigation (for periods of extreme drought) is a
wise investment. This can simplify maintenance, and help the plants
acclimate to the individual site. One or two visits to the roof per
year for weeding and/or evaluation of plant survival is vital not only
to ensure that the roof is functioning as it should, but also to keep
weed pressure down and allow the plants to establish properly.
How do green roofs fit into LEED certification? The Leadership in Energy and Environmental Design (LEED) Green Building Rating SystemTM
is an internationally accepted benchmark for the design, construction,
and operation of high performance green buildings. Green roofs can
contribute as many as 15 points towards a building's LEED rating.
How do I install a green roof? If
you choose to install a green roof on your own be sure to do your
homework first, and definitely consult with the experts. Since it's
still a new concept in the Pacific Northwest, we have much to learn.
Plus, successful installations will help secure positive perceptions of
rooftop greening. Various companies install green roofs, from
landscapers to roofers, and the specialized green roof components are
necessary to ensure proper drainage, loading, etc. Here are some
recommended links:
Soprema - Membranes and associated structures RoofScapes -Membranes and drain mats Stream Organics - Suppliers of specialized soil Flynn Canada - Complete installation of commercial green roofs Paradise Cityscapes - Installation of private green roofs BCIT Centre for the Advancement of Green Roof Technology - Hub for green roof infrastructure network in GVRD, and engaged in ongoing research, education and demonstration. 
What about plants for a green roof? NATS
Nursery has been an expert in Pacific Northwest Native plants for over
19 years. Visit the CATALOGUE to learn about the plants we have
available for your green roof and living wall projects. Please note:
there are many other species that may be suitable for your roof or
wall, depending on its individual ecology. Also note: it is important
that you discuss these projects with us as soon as possible to ensure
the correct lead-in time so that you are able to get the unique species
you may want.
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