Posted by: Daryl & Wendy Ashby | November 23, 2010

Green Roofs Only Add Cost

When the City of Richmond passed a bylaw in 2008 that green roofs would become a component on large industrial buildings, the news was greeted with applause in the environmental community.

But some developers suspect that green roofs will prove expensive and could add risk to a building’s performance.

“Green roofs don’t make much sense in BC’s climate, ” said Ron Emerson, president of Emerson Real Estate Group Ltd. “They do nothing for an industrial building but add to the cost.”

According to Emerson, green roofs are politically trendy but proponents fail to realize the sophistication of new commercial buildings.

“There are millions of dollars work of sensitive electronics and technology in contemporary office and industrial structures,” which cannot be threatened by roof leaks, He said.

And despite assurances that properly built green roofs should not leak, Emerson said the roofs have not been in the market long enough to know for sure. He also worries about the weight of a green roof after a typical winter in heavy BC rains.

Mould is also a potential headache Emerson added, and insurance issues have already been raised about green roofs on new buildings.

In fact, giant Swiss insurer Zurich posted a warning last year that green roofs could represent a fire hazard. The Canadian Roofing Contractors Association;s technical director, Peter Kalinger, confirmed that, “There are no currently accepted tests for determining the fire performance of vegetative roofs.”

The City of Richmond notes that its green-roof bylaw is not mandatory, since developers can opt for other green measures to make a building compliant. But for those owners who do add roof plantings the cost can be high and ongoing. Should a builder add such a roof, the City of Richmond requires the owner to “register a covenant on the title of the building site in favour of the city to indicate that the owner shall, in perpetuity or until approved redevelopment, maintain the green roof, planting media and plant material in accordance . . . replacing each as necessary to ensure that the roof performs as designed.”


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