Green Roofs Image

Green Roofs

By on Sep 07, 2007

by Laryssa Stolarskyj

What's next in the evolution of creating a more

healthy and beautiful city? Energy efficiency

and sustainable living are buzz phrases, and as

conscientious citizens-both individuals and businesses-

we need to incorporate changes to existing structures and

lifestyles to do our part.

Green roofs are poised to be the newest development in

designing healthy cities. The concept may sound new to us, but green roofs have actually existed for over 5,000 years; the

lightweight modern versions are rooted in the German

ecology movements of the 1960s and ?70s. Here in Toronto,

Steven Peck is founder and president of Green Roofs for

Healthy Cities (GRHC), a network of public and private

organizations formed in 1999 after a report was issued

outlining the benefits of green roofs. Today, it is

a non-profit formal industry association promoting its

philosophy throughout North America about the economic,

social, and environmental advantages of these structures.

A green roof is an extension of an existing roof and

consists of various additional layers that include water

proofing, root repellant, drainage, filter, growing medium,

and vegetation. Typically, a green roof has less than six

inches of growing medium and low plant diversity

maintained at minimal cost as opposed to a rooftop garden,

which has greater than six inches of growing medium that

entails a higher cost and more plant diversity.

Peck enthuses about the benefits that green roofs have for

a city. "The big [benefits] are reduced energy consumption,

reduced urban heat island effect [1-2°C in Toronto from just

5 per cent roof coverage], and retained stormwater, which

reduces beach closures, erosion management, and pollution

from combined sewer overflows. Green roofs also strip particulate

matter from the air, help to eliminate smog, and can

contribute, if they are planted right, to biodiversity conservation.

The York University green roof has four regionally

rare species of plants according to the Toronto and Region

Conservation Authority."

The benefits are even more plentiful: they also reduce

greenhouse gases including carbon dioxide, improve air

quality, insulate sound, extend the life of the roof by up to

twice as long, save on heating and cooling costs, provide a

source of food production, create a habitat for birds, add

aesthetic appeal, increase the property value of homes, and

can even improve employee productivity.

Mike Mulqueen is an assistant planner for The City of

Toronto's City Planning Division. He says that 77 green

roofs exist in their inventory: 52 private and 25 public

practitioners, including projects at 215 Spadina Avenue and

Mountain Equipment Co-op on King Street West.

He also

highlights the Green Roof Incentive Pilot Program, which

is designed to give "eligible property owners a grant of $10

per square metre of acceptable green roof area to a maximum

grant amount of $20,000 as an incentive to install a green

roof?The program will be open to all owners of private

property in the City of Toronto irrespective of building size

and type so long as the building is capable of supporting a

green roof that meets the program's requirements."Talks are

currently underway for Toronto Hydro and the Toronto

Atmospheric Fund to contribute to the project.

If you're interested in growing your own residential green

roof, some important requirements to consider are your

roof 's structural loading capacity, its slope, the existing

materials, drainage systems, and exposure to the elements.

Contact a green roof manufacturer to find out about

landscape architects and qualified roofing contractors who

can professionally install a green roof for you.

The Annual International Greening Rooftops for

Sustainable Communities Conference is taking place in

Boston this May.Visit to learn more or see

the City of Toronto's website at

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