Transforming Condo Rooftops into Green Oases 

Virtual tour of Toronto Sky Gardens and Urban Greenspaces

The City of Toronto is a leader in the green roof movement with more area constructed per year than the rest of Canada combined. Many of these green roofs sit high up atop condos and are not visible from the ground.

Avani condo green roofs supplied by Next Level Stormwater Management. Photo gvrpix.com

Pollinator Corridors and Much More

While some offer nature escapes for urban dwellers, others provide safe habitats for birds and insects, manage stormwater, save energy, mitigate the urban heat island, clean the water and air.  Let’s take a bird’s-eye view…

The Form condo green roofs supplied by Next Level Stormwater Management. Photo gvrpix.com

Keys to Success

A successful green roof is a combination of good design, detailed construction and proper maintenance. Being up on high-rise condos present added challenges. Next Level collaborates with top designers transforming rooftops to make cities more livable and resilient. See considerations below. 

Sherwood on Huntington green roofs supplied by Next Level Stormwater Management. Photo gvrpix.com

Design Considerations

Design considerations include access, loading, microclimate, roof membrane assembly and wind.  More information and links below.

Islington Terrace green roofs supplied by Next Level Stormwater Management. Photo gvrpix.com

Access: For roof gardens that are accessible, provide safety railing, proper lighting, signage, clearly marked exits and wheelchair access. Inaccessible green roofs should be equipped with roof anchors that enable landscape crew to conduct maintenance safely. 

Loading: Typical saturated weight ranges from 60 – 200 kg/m2 (12 – 40 psf) for extensive green roofs to 250 – 500 kg/m2 (50 – 100 psf) for intensive roof gardens, with soil-less options being the lightest. Pedestrian traffic, outdoor furniture and hardscapes incur additional live loads.  

Microclimate: While vegetation located on roof level are more exposed to sun and wind, those on podium levels can be shaded by surrounding structures at different times of the day. Windows and metallic claddings can reflect heat onto the plants while air exhaust can dry them out.  

Protected Membrane Roof Assembly (PMRA): Most condos use PMRA where the roof membrane is installed under the extruded polystyrene insulation. The vegetated system must be designed in harmony with the roofing system to ensure overall performance.  

Wind: Wind speed and uplift pressure increase with building height; and can become quite high on high-rise condo rooftops. Select vegetated roof assemblies that have been tested to CSA A123.24 with proven wind resistances. 

Construction Considerations

Construction considerations include foot traffic and leak detection.  More information and links below.

The 4 Kingsway green roofs supplied by Next Level Stormwater Management. Photo gvrpix.com

Foot Traffic: With many trades rushing to meet deadlines, construction management is critical to minimize damage to rooftop vegetation. Ideally, the green roof should go in last. At a minimum, temporary protective measures should be set up to minimize foot traffic damage by other trades. 

Leak detection: A leak detection system such as the Electric Field Vector Mapping can be installed to check and locate any breach in the roof membrane before and after the green roof installation. It can also be set up for continuous monitoring during service for the peace of mind. 

After Care Considerations

After care considerations include maintenance and irrigation.  More information and links below.

508 Wellington green roofs supplied by Next Level Stormwater Management. Photo gvrpix.com

Maintenance: Intensive green roof systems involving shrubs and trees require regular trimming and pruning.

Extensive green roof systems contain smaller native or adapted plants that are hardy, heat and drought tolerant, and require less maintenance. See our maintenance guidelines for more details. 

Irrigation: Irrigation requirements depend on weather, microclimate, plant selection and owner expectations. While irrigation system is generally not necessary on properly designed green roofs in Toronto, a hose bib is required to provide relief during prolonged heat and drought. 

Transform Your Rooftop into a Green Oasis

Attend Next Level Stormwater Management’s upcoming  live interactive webinar, email a member of our sales team or call (416) 637-5772.

Avani green roof supplied by Next Level Stormwater Management. Photo gvrpix.com

Next Level Stormwater Management logo in bold blue with logo above in blue and green

More than 2M SQFT supplied coast to coast

Next Level Stormwater Management is Canada’s leading supplier of pre-vegetated roofs such as LiteN’Less™, Xeroflor® and StormCap™ systems. We customize to local requirements and offer warranty and maintenance support. Our team provides analytical support such as ​stormwater calculations specific to location ​and building/roof type, the latest green roof stormwater data and related innovative hydrologic modeling tools.
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