Toronto's 2009 bylaw made green roofs mandatory on new mid-to-large buildings, delivering 1,200+ green roofs and 450,000+ m² of coverage, linked to ~11 million litres of diverted stormwater a year — until Ontario repealed it by order-in-council in November 2025.
450,000 m²
Green roof space installed (2010–2017)
11 million litres/year
Stormwater diverted annually
220 tonnes/year
CO2e avoided annually
Details
Maturity
Discontinued
Promoter
City of Toronto (Toronto Building / Environment & Climate Division)
Period
2009–2025
Keywords
building regulation, urban green infrastructure, stormwater management
Context
Adopted by Toronto City Council in May 2009, the Green Roof Bylaw was North America's first mandatory green-roof regulation, setting graduated coverage requirements from 20% to 60% of available roof space for new buildings by size.
Results
The City attributes roughly 420 permits and 450,000 m² of green roof space (2010–2017) to the program, with about 11 million litres of stormwater diverted and 220 tonnes of CO2e avoided annually — but Ontario repealed the bylaw by order-in-council effective November 2025, making green roofs voluntary again.
Implementation
Indicative cost
Medium (€50k–€500k)
Time to results
Long (> 3 years)
Staffing & skills
City of Toronto Building / Environment & Climate Division
Conditions for success
Graduated size-based coverage thresholds with cool-roof or exemption alternatives for smaller buildings
Common failure modes
Provincial order-in-council repealed the mandate in November 2025 citing housing-cost concerns
Commonly funded by
National / regional programmes
Indicative funding routes for practices of this type — always check each programme's current calls and eligibility rules.
Do you run this practice?
Claim it —
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Data sources
Where this practice's information was retrieved from, and when.
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