Initiatives are growing to have building roofs become
Environmental degradation, urban sprawl, waning water resources,
increase in population, and dependence on imports are all factors
putting significant pressure on the food supply. Urban rooftop
farming, pioneered by local food and sustainable agriculture
movements, has developed to alleviate some of that pressure.
The rooftop farming trend is more prominent in the U.S., where
many municipalities have responded with favourable bylaw and zoning
amendments to create urban agricultural districts and permit
farming in residential zones. Brooklyn Grange operates the
world's largest rooftop soil farms located on two roofs in New
York City operating under 10 and 20 year leases. One of the farms
is 43,000 square feet containing approximately 1.2 million lbs. of
soil. Brooklyn Grange grows over 50,000 lbs. of produce per
Canadian municipalities are beginning to respond to the growing
demand for urban agriculture and rooftop farming. The City of
Edmonton's "fresh: Urban Food and Agriculture
Strategy" (October 2012) identified rooftop gardens in the
inner urban area as an opportunity for food production and
recommended that the municipality assess regulatory barriers for
In November 2013, Toronto City Council adopted the Toronto
Agricultural Program, which included the Urban Agricultural
Workplan. A component of the plan is promoting urban agriculture on
rooftops through the Eco-Roof Incentive Program. Toronto also has a
Green Roof Bylaw requiring green roofs on new commercial,
institutional and residential developments with a minimum gross
floor area of 2,000 square metres, to be built in accordance with
the Toronto Green Roof Construction Standard (Toronto Municipal
Code, Chapter 492, Green Roofs).
Similarly, a Green Roof Bylaw in Port Coquitlam, B.C. requires
new commercial or industrial use buildings having a building area
of 5,000 square metres or more to have a green roof on at least 75
per cent of the roof area (Zoning Bylaw, 2008, No 3630, s
Zoning and bylaws, including green roof bylaws in most Canadian
municipalities, are not specific to rooftop farming.
However, the absence of such specificity has not prevented the
establishment of urban rooftop farms across Canada. To name a few:
Lufa Farms has a 31,000 sq.ft. rooftop greenhouse in Montreal
(www.lufa.com). In Vancouver, the downtown YWCA Metro Vancouver has
a rooftop food garden which had a harvest of 720 kilograms in 2012
In terms of opportunities, rooftops represent an abundant
farming resource in dense urban areas. Rooftop farms reduce
greenhouse gas emissions by reducing transportation costs and
environmental impacts. They allow the absorption of stormwater
which reduces the strain on drainage systems, and they cool urban
Rooftop farming also supports local businesses and the local
food supply industry. It creates sustainable and economic
opportunities for repurposing unused spaces, lends itself to
creative leasing arrangements and is a natural progression for the
design and construction of green buildings.
Consequently, municipalities should expand their efforts to
accommodate rooftop farming. Doing so would counter public concern
over the decreasing areas of green space.
Engineers who may become involved in designing rooftop farms
should consider the following:
municipal plans, bylaws and
strategies for urban agriculture;
municipal zoning and permits
municipal laws for pesticides,
fertilizers, water contamination, landscaping and noise
existing building integrity including
structural capacity, access and drainage
building code specifications for
structural integrity and requirements for plans and drawings
weight capacity including for soil,
vegetation, irrigation and equipment with allowances for seasonal
sufficiency of the waste management
insurance requirements and allocation
of risk in leasing agreements
incentive programs and tax
While the concept of rooftop farming is relatively novel, it
stands to become more prevalent, providing an excellent opportunity
for cutting-edge engineers to be proactive and to contribute to
Originally published by Canadian Consulting Engineer,
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Russell v. Township of Georgian Bay provides a useful reminder of the fact that while municipal officials sometimes appear to hold all of the cards in disputes with home owners, that is not always the case.
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