In 2009, Toronto was the first North American City to pass a bylaw that required all commercial, residential, and institutional buildings over 2000 square metres to have “vegetative roof coverage.”
Depending on the size of the building, the green roof portion has to cover between 20 and 60 percent! That may seem like a drastic requirement, but Toronto wants to position itself a leader in green roof adoption.
As more major cities follow in Toronto’s footsteps, it won’t be long before Edmonton enacts similar green development bylaws.
Strathcona County already has buildings with green roofs, including its Community Centre where you’ll find a grass-covered green roof on Council Chambers. Take a look at all the green initiatives they’re taking with the centre here (including rainwater collection for their toilets!).
The Many Benefits of Green Roof Systems
A roof is there mainly to protect the structure from the elements. It helps keep you warm and dry. But a green roof goes above and beyond its basic duties:
- Beautifies the space
- Increases biodiversity
- Creates habitat for animals and insects
- Reduces the “heat island effect”
- Reduces noise pollution
- Helps regulate temperature in the building
- Increases energy efficiency
- Slows release of rainwater into sewer systems
- Increases stormwater quality and quantity
- Improves air quality
The only downside to a green roof is the cost, which can be substantially higher than a typical flat roof system. For more about the cost of a green roof system, read on.
Styles of Green Roofs
The two different types of living roofs are intensive and extensive green roofs.
Intensive Green Roof Systems are also known as Rooftop Gardens. This is the type of green roof that will have walkways, benches, ponds, fountains, and other features in addition to trees, shrubs, and flowers. They are made for people to enjoy and are irrigated and maintained regularly.
Extensive Green Roof Systems are lower maintenance and higher performance green roofs. These use hardy, utilitarian plants with shallow roots that will give you all the benefits of a green roof without all the maintenance. They also require less structural support than a rooftop garden, so they can easily be added to existing roofs.
How Green Roofs are Made
A green roof is like an onion. It has many layers. The top layer is the vegetation and growing medium. Then underneath are layers: root growth inhibitor, waterproof membrane, and a drainage system.
Want more details about how green roofs work? Godfrey Roofing Inc. wrote an article about green roofing where they go into details about the layers of a typical green roof.
Commercial Products Available
There are a few commercial green roof system products on the market right now. Soprema’s has a green roofing products line, SOPRANATURE that has a range of nice options to choose from.
There will definitely be more companies making green roofing products in the future, so keep an eye out for improving techniques and competitive pricing.
Plants for a Green Roof System in Alberta
With interest in green roofs picking up, NAIT ran a study to test which plants fare the best as rooftop plants in Alberta for a low-maintenance green roof system.
They found that the hardiest plants are the ones we find here naturally, which shouldn’t surprise you.
The plants that can withstand direct sun, high winds, infrequent watering, and extreme temperatures were the grasses and sedums native to Alberta.
*Note: Green roofs are not meant to provide food. Constantly uprooting the plants can damage the green roof system.
For rooftop gardens, plants that do well in containers will do the best. Vegetables like tomatoes, cucumbers, and salad greens and flowers like petunias, marigolds, and zinnias.
How Much Does a Green Roof Cost?
The price of the roof components, installation, and maintenance for a green roof vary, but a typical low-maintenance/extensive system should cost between $15 to $20 per square foot.
You can expect a green roof to last well over 50 years, which is double the life of the average asphalt shingle.
Are Green Roofs Going to Become the Standard?
We’re interested to see if/when commercial green roofs become the standard in Edmonton.
Are you interested in commercial green roofs? Let us know what you think.
For your commercial roofing needs, Crest Roofing has you covered.
Call the roofing experts at (780) 466-1601.