Putting green roofs on commercial and residential buildings is a growing business in Canada.

The green-roof industry blossomed more than 25 per cent in 2006, with more than three million sq. ft. of the environmentally friendly roofing material installed on buildings across the country, according to a study by Green Roofs for Healthy Cities, a not-for-profit industry association based in Toronto.

But the trend isn't just rooted in a desire to save the planet - it's a desire to boost the bottom line.

"Green roofs offer both public and private benefits," says Karen Liu, acting program head for the British Columbia Institute of Technology (BCIT) Centre for the Advancement of Green Roof Technology.

Photo courtesy of Xero Flor
Joy Schmidt of Xero Flor stands atop the green roof of the 10.4-acre Ford Motor Co. assembly plant in Dearborn, Mich.

Liu says green roofs help with stormwater management, mitigate the urban heat island and improve air quality in cities.

Building owners benefit by reducing their heating and cooling costs.

"Green roofs also extend the life of the roof by moderating the extremes of temperature experienced by conventional roofing material. They increase the property value of their building," adds Liu.

BCIT set up the Centre for the Advancement of Green Roof Technology in 2004 to conduct research and development to improve green-roof technology and to address the challenges of importing this European technique to the harsher North American climate.

CEO Joy Schmidt of Brantford, Ont.-based Xero Flor Canada, says growing research and education about green roofs are raising interest with the public, conventional roofing companies and with municipalities.

Xero Flor Canada specializes in low-maintenance roof gardens designed to decrease the environmental impact of buildings.

Although the company's Canadian branch was established in 2001, its green-roof technologies started in Germany about 35 years ago, says Schmidt. "Back then, Xero Flor provided reinforced turf for slopes and embankments. This led to the development of reinforced vegetation systems for green roofs," she says.

German towns and cities required new flat-roofed (buildings) to have a green roof installed, she adds. "The need for low-weight, low-cost and low-maintenance systems guided such property owners towards plants that were resistant to cold, heat, drought, shade and bright sunshine. That's where our experience with turf cultivation came in."

Since then, the company's green-roof systems have been used on thousands of installations worldwide, including a 10.4-acre Ford Motor Co. assembly plant in Dearborn, Mich.

Another Brantford company, called Elevated Landscape Technologies Inc. (ELT), is also participating in the growth of the green-roof industry.

Photo courtesy of Soprema Inc.
A Canmore, Alta., private residence sports a Soprema green roof that is part of a growing trend.

ELT was incorporated in 2001 as a company that would install green-roof systems for clients, says owner Greg Garner, who came onboard in 2004 and transformed ELT from a sub-contractor to a green-roof supplier.

"We provide several services such as design, consultation, project management and installation. But education is the focus for our company, spreading the word about green roofs," says Garner.

"It is getting easier now, as the exposure for green roofs has increased, along with the increased exposure of the environmental challenges we face."

Quebec-based Soprema Inc. manufactures a variety of modified bitumen roofing systems for green-minded builders.

The Drummondville firm has developed the Sopranature green-roof system, which includes water-retention, irrigation and root-barrier layers, as well as suggested plant materials tailored to different climactic conditions.

Its Cordillera system, for instance, has a variety of drought-resistant plants that are suitable for sloped roofs.

"We have installed over 200 green roofs in Canada, including institutional, residential and commercial buildings since 1996," says Marie-Anne Boivin, co-ordinator of Sopranature development.

Soprema also has a second plant in Chilliwack, B.C.

"The Canadian climate is very diversified," Boivin notes. "Cities at the same latitude have different minimum and maximum temperature and precipitation levels, so we have to vary the vegetation to accommodate these conditions."

Green roofs are not a matter of throwing down dirt or sod onto a roof.

The growing material has to be separated from the structure of the building by the use of a vapour barrier, thermal insulation and a waterproof membrane. A root-resistant layer ensures that roots don't compromise the roof structure. On top of this comes the growing medium and the plants.

"If you're going to install a green roof, you need to plan ahead," says Xero Flor's Schmidt. "You may need additional structural support, so design it early. And expect to pay a premium for the product, although you will make back some of those costs over time.

"Be careful of the materials you use. Steps must be taken to ensure that these materials don't become fire hazards; that they can handle the changes in temperature. Finally, it's important to maintain your roof, especially during the first year, so that the plants have a chance to establish themselves."

Even more challenging is retrofitting existing buildings to handle green roofs.

Existing buildings were designed to support a climactic dead load specific to each region, says Boivin.

However, new light-weight growing mediums don't add significantly to the structural component, providing the opportunity for rooftop gardens on many existing buildings, including those with limited structural capacity.

Meanwhile, green-roofing companies are looking toward a bright green future.

"To this point, the industry has been led by forward-thinking people willing to do what they believe to be right," says ELT's Garner.

"We are starting to see municipalities initiate programs that provide incentives for people incorporating green roofs into their development strategies."

Last year the City of Toronto initiated a pilot program offering $10 per sq. m up to $20,000, as an incentive to build green roofs. Many other municipalities are expected to follow.

"How intensive this becomes still has to be seen," says Schmidt. "It's going to take a while before these things come through, because one of the first steps is understanding the technology, putting policies in place and then putting incentives in place."

Soprema's Boivin agrees. "The industry will grow and green roofs will be a part of the global solution, especially if building owners can benefit from economic incentives like tax cuts or improved energy efficiency."

(James Bow can be reached at bow@businessedge.ca)