July 6, 2007

Environment

Turning a new leaf towards green roofs

Majority of projects company tackles are new buildings

IRWIN RAPOPORT

correspondent

Over the last two-and-a-half years, Toronto-based Gardens in the Sky Inc. has designed and created about 20 extensive green roofs in Ontario.

While conventional roof construction still holds sway, green roofs are becoming more popular, especially among those putting up LEED buildings (Leadership in Energy and Environmental Design) and ‘green’ buildings, where the focus in on energy savings, efficiency and a reduced impact on the environment.

Roofs are extensively prepared prior to installation of tiles, soil and plants. Currently about 75 per cent of green roof projects are installed on new buildings.

Terry McGlade, the owner and president of Perennial Gardens, established Gardens in the Sky in 2004 in order to specialize on green roof design and construction. McGlade installed his first green roof in 2000 and has built roofs for ICI and residential construction between 8,000 and 12,000-square-feet.

“We’re working on projects for next year, including two or three condominium developments in downtown Toronto,” said McGlade, who recently built roofs for the Accelerator Building in Waterloo, Ryerson University’s new computer science building and a structure at the Toronto Botanical Gardens.

GARDENS IN THE SKY INC.

Another advantage of green roofs is reduced energy costs and the way in which the roofs assist with storm water management.

“The green industry is still very much in a shakedown cruising aspect,” he said. “Building methods have changed since we started six years ago. Typically, it will take us four days to do a green roof. If we get more involved in the roofing aspect, such as putting in insulation, roof barriers and other elements, it can take a long time, depending upon the size of the roof.”

An extensive green roof usually has a soil depth of six inches, while an intensive roof has a soil depth of two to three feet.

A green roof is placed above a standard roof membrane, separated by a barrier.

It is essential to secure the trust of roofing companies.

“They want to make sure that the people coming onto the roof are not going to poke holes in it,” said McGlade. “We give them quality assurance that we know what we are doing. It’s a real sense of cooperation and we take extreme care and caution up on those roofs.”

Approximately 75 per cent of the roofs built by McGlade were for new construction, the remainder being retrofits.

When possible, McGlade prefers situations when his firm can participate in the initial design phase of a building so that the roof specifications – the parapet wall and selection of materials – can be integrated into architect’s vision.

Green roofs also require annual maintenance, which the firm can also provide.

In terms of plant selection, the trend is for more biodiversity, with a preference for native plants, mainly because of their longevity and reduced need for maintenance.

After the base is put in place, workers bring in the soil which will house the appropriate plants to keep the roof green and energy efficient.

Green roofs have four basic advantages:

• They reduce the heat island effect that the building throws off into its local environment.

• They help in storm water management – the water that hits the roof, stays on the roof.

• They reduce energy costs because the building is not heating up in the summer very often, which reduces need for air-conditioning.

• They create a new environment on sites where there was no green space, which helps to reduce smog and the replacement of green space that previously occupied a building footprint.

While there is an initial cost to put up a green roof, there is a definite energy savings.

To protect a building’s infrastructure from leaks, an electric wire detection system is placed below the green roof that establishes a grid system to accurately pinpoint potential trouble spots.

While the green roof business is still establishing itself in Canada, many jurisdictions in the United States, such as the cities of Chicago and Portland and the State of Maryland, are embracing green roofs.

McGlade foresees the day when green roofs will become a standard building practice in many parts of Canada, especially as many government-owned and government-financed buildings are seeking LEED designation.

“We fulfill a certain criteria for LEED points and the green roofing system is very durable,” he said.

The completed project sets up a green site which requires annual maintenance.

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