Toronto’s Green Roof Requirements Take Effect Monday

29 01 2010

Downtown Toronto
Photo Credit:

On Monday, Toronto’s ambitious
green roof standards will go into effect. Any roof of a building over 2,000m2 will be required to include a green roof for a portion of the building. High-rise tower roofs that are 750m2 or less are exempt. The following is the breakdown of the required percentages of the roof area based on its size:

  • 2,000m2(21,528sf*) to 4,999m2 (53,809sf*) = 20%
  • 5,000m2 (53,810sf*) to 9,999m2 (107,629sf*) = 30%
  • 10,000m2 (107,630sf*) to 14,999m2 (161,449sf*) = 40%
  • 15,000m2 (161,450sf*) to 19,999m2(215,269sf*) = 50%
  • 20,000m2(215,270sf*) or greater = 60%

*square footage calculations are approximate

These standards will initially cover all building types with the exception of industrial. Industrial building requirements will take effect in 2011. To put these standards into context, the 20% requirements would include a typical modern office building to a medium size neighborhood grocery to a smaller big box store. Most stand alone restaurants and smaller residential projects would likely not meet the threshold to require a green roof. The other requirement levels would cover larger big box and larger grocery stores, significant retail centers, and industrial/warehouse facilities.

Interestingly, the available roof area that is used to calculate the requirements excludes areas designated for renewable energy, private terraces, and residential amenity areas (to a maximum of 2m2/21sf per unit).

The City’s eco-roof incentives program that provides $50/per m2 up to a maximum of $100,000 is still in place. According to their website, applications are being accepted starting March 1st. The deadline is April 1st. Award projects will be decided on April 16th.

This initiative is being launched in conjunction with the City’s new Green Standards Program. It reminds me of the United States Green Building Council’s (USGBC) LEED checklist. The program includes three categories, each having their own but similar requirements. The categories include low-rise non-residential, low-rise residential, and mid-high Rise (any use).

Additionally, the new standards do encourage green infrastructure requirements such as:

  • Retain stormwater on-site to the same level of annual volume of overland runoff allowable under pre-development conditions and retain at least the first 5 mm from each rainfall through rainwater reuse, onsite infiltration, and evapo-transpiration or ensure that the maximum allowable annual runoff volume from the development site is no more than 50% of the total average annual rainfall depth
  • Remove 80% of total suspended solids (TSS) on an annual loading basis from all runoff leaving the site based on the post- development level of imperviousness. Control amount of E. Coli directly entering Lake Ontario and waterfront areas as identified in the Wet Weather Flow Management Guidelines

Due to the legal ramifications of a continually evolving third-party system like LEED, we will likely see more city -specific green building programs being developed over the coming decade as cities seek to separate themselves and focus on the particular aspects of sustainable design that have the largest impact in their community.

You can find all of the standards on the City’s website here.

-Brian Phelps



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