Some Green Roofs Are Mandated And Governed By A City Of Toronto By-Law

Green Roof Construction

Green roofs, sometimes called rooftop gardens, consist of a layer of vegetation planted in a growing medium that in turn sits on a waterproof membrane, all on the surface of a flat roof. It may may also contain an additional layer or layers to address water drainage and irrigation, if the roof is designed to act primarily as an accessible park with trees, bushes, shrubs, walkways, and seating areas – such parks are known as intensive green roofs. Conversely, extensive green roofs are those that not designed to serve as accessible rooftop gardens and basically consist of hearty, low-maintenance ground cover.

Whether green roofing is extensive or intensive, these types of gardens serve several environmental purposes, including:

  • Increasing vegetation – by making use of existing space
  • Reducing energy costs/consumption by providing natural insulation
  • Providing shelter and habitats for animals (primarily birds)
  • Absorbing storm water, thereby reducing the need for drainage systems
  • Improving overall air quality, especially in major urban areas
  • Moderating temperatures – by preventing absorption/trapping of heat
  • Noise reduction – serving as a sound barrier or insulation
  • Recycling – via materials used for growing mediums/waterproof membranes

Although green roofs have a certain amount of aesthetic appeal, plus practical utility and environmental benefits, they are also subject to a City of Toronto by-law that came into effect in January 2010. This by-law now mandates green roof construction on any new developments with a minimum gross floor area of 2000 square meters, as it pertains to the following structures:

  • Residential (more than five stories in height)
  • Commercial
  • Institutional
  • Industrial (with some specific exceptions)

The green roofing requirement, or the percentage of available roof space that must be covered by the green roof, is determined by a graduated scale that ranges from 20% to 60% depending on the size of the building or structure.

Over and above this percentage or area that must be converted per the City of Toronto by-law, green roof installation requires several additional and important factors that must be taken into consideration during the design phase. Many of these following structural or design factors will also influence whether extensive or intensive green roofs will be implemented:

  • Weight/load on the roof
  • Ease of accessibility from the interior
  • Maintenance access – for the garden and for the building itself
  • Safety – for pedestrian traffic; building fire codes/regulations
  • Choice of vegetation and growing medium
  • Slope capacity/drainage system
  • Orientation – based on sun/wind direction

Whether the installation of green roofing is mandated for your building by the current City of Toronto by-law or you wish to add aesthetic and environmental appeal to an older structure, the complexity of the process would make the professional services of green roofs specialists, such as the team from Landcare, highly advisable.

Our Accredited Professionals Offer Exceptional Green Roof Installations

The green roofing services of the Landcare team consist of the design phase, on-site inspection/analysis, construction/installation, and maintenance. Much of this process is influenced and overseen by Rob Crysdale, Landcare’s owner and an accredited Green Roof Professional.

Rob’s knowledge and experience in green roof installations can be highly valuable assets to your particular project, especially in relation to understanding and fulfilling the City of Toronto by-law requirements. You will receive expert advice on such matters as:

  • Minimum percentage of green roof
  • Weight or load capacity
  • Best options for vegetation and growing medium
  • Weather considerations (micro climates)
  • Safety, irrigation, and lighting options
  • And much, much more

To ensure the knowledgeable and experienced green roof installations in Toronto and the GTA, call the professionals at Landcare today at 416-410-0320 or contact us to gain more insight and to exchange ideas.