Daily Commercial News — Hugh Garner Housing Co-operative will boast largest green roof in Canada

Daily Commercial News - Hugh Garner Housing Co-operative will boast largest green roof in Canada

by Peter Kenter Jun 3, 2010

The eight-storey Hugh Garner Housing Co-operative, located in the heart of Torontos Cabbagetown, has officially opened the second phase of what will be the largest residential green roof project in Canada.

The eight-storey Hugh Garner Housing Co-operative, located in the heart of Torontos Cabbagetown, has officially opened the second phase of what will be the largest residential green roof project in Canada.

The co-op celebrated the opening of its 8,000-square-foot south roof, a barrier-free garden open to the buildings 300 residents, on May 26. Toronto Deputy Mayor, Joe Pantalone, who has championed the citys Green Roof Bylaw, was on hand to participate in the ribbon-cutting ceremony.

The project achieved its first milestone in 2007 with the installation of a waterproof, root-resistant membrane by Tremco Ltd.

The final phase will involve an intensive 14,000-square-foot green roof on the buildings north side.

The project has been shepherded through development by a residents green committee chaired by Beata Domanska.

Monica Kuhn, principal of Monica E. Kuhn Architects, Inc. has worked with residents for seven years on the project, which is proceeding methodically as grants and funding fall into place.

The project stemmed from an initial decision to replace the original failing roof membrane with a root-resistant membrane.

Kuhn notes that the project was not without its challenges, including the roofs structural loading capacity.

We worked with a structural engineer to discover the location of the shear walls, which divide the units, says Kuhn.

Those structures go right to the ground so we were able to load those areas up with planters.

Terry McGlade, Manager of Gardens in the Sky, a division of Flynn Canada Ltd. masterminded the garden portion of the green roof.

Daily Commercial News - Hugh Garner Housing Co-operative will boast largest green roof in Canada

The roof now forms a reservoir about four inches deep that prevents precipitation from overloading the citys stormwater system while providing moisture for vegetation housed in white cedar planters.

A series of drainage boards support the buildings original concrete pavers, which provide the roofs walking surface. A stream running underneath the pavers in the centre of the roof is recirculated through the system via electric pump.

McGlade notes that Canadas experience with green roofs spans only about a decade. Some types of vegetation considered a slam-dunk for area roofs have failed, while long shots have succeeded.

Most people would think a Japanese maple would fry on a roof like this, says McGlade. Our experience has been that, because it has a very small root ball, it will thrive. Over the years weve discovered a whole new palate of plants that will survive.

McGlade says his design accommodates a wider variety of vegetation by varying the depth of soil from as little as four inches to about two feet.

Future plans for the north roof include an extensive planting of hardy, low alpine vegetation, the installation of flat plate solar collectors to heat water and reduce natural gas consumption, and the addition of photovoltaic panels to power sprinkler pumps and reduce electricity use.

Additional industry partners on the project include Moss Sund Inc. Sustainable EDGE, K.H. Davis Consulting and Toshiba. Financial support includes grants from the Co-operative Housing Federation of Toronto Charitable Fund, the Ontario Trillium Foundation and the City of Toronto.

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