A green roof is a specialized roofing system that supports vegetation grown above the roofing system. The complexity of the green roof depends on the type of system used. Here in the Burlington and Oakville area (and throughout the GTA), green roofs can either be intensive or extensive or modular in design. Green roofs also have a wide array of benefits ranging from economical to environmental.
An intensive system of green roof is one that has a thicker base layer of media and can support a much wider variety of vegetation. The types of vegetation supported by this system include a wide variety of plants, small trees and other types of vegetation. An intensive green roof is more versatile and can be used as a park like setting giving architects a new design platform to work with. They do, however, require a minimum of 10” – 12” of base material which for many roofs exceeds the weight limit for which they are designed for.
An extensive system is similar to an intensive but only has 2” – 4” of base material. They tend to be somewhat fragile and should only have light traffic to avoid damaging the root systems. Paths are often made through the extensive roof system to avoid damage.
The latest and most Hi-Tec of all the green roofing systems and the one that is commonly found in flat roofs around the GTA area is the modular system. A modular roof is one that is grown in a controlled environment, using specialized container modules that each supports their own complete system of base material and plants. These modules are installed on the roof and are easy to maintain and durable enough for foot traffic. The modular roof is an extensive system and usually ranges in depth from 3” – 12” in depth.
Maintenance Requirements
The level of maintenance on a green roof depends on the type of system used, the thickness of the media and the types of plants used. Extensive green roofs that contain sedums and grasses usually requires little to no maintenance unless there is a long-lasting drought. Intensive systems require much more maintenance and usually have self-contained watering systems installed for ease of watering. Self-contained, modular systems are equivalent to an extensive system and require little to no maintenance.
Environmental Benefits of a Green Roof
The biggest benefit of a green roof is it replaces the vegetation that was lost when the building was erected. They are also excellent at reducing the amount of rain storm runoff easing the city’s drainage systems. They are capable of absorbing large amounts of moisture from rainfall thus they greatly reduce flooding, and erosion. They are capable of releasing the contained water in a much slower manner than a traditional flat roof.
Green roofs also reduce the heating and cooling requirements of the building as they absorb the heat from the sun and turn it into energy that the plants use. In the winter, the thick layer of vegetation insulates the building and reduces the amount of warm air escaping through the roof.
Financial Benefits of a Green Roof
Green roofs reduce the heating and cooling costs of the building and last much longer than traditional flat roofs. The added expense of installing a green roof is off-set by the benefits and cost savings it creates over time. Green roofs in Burlington and Oakville (and throughout the GTA) not only increase the property value, they increase the attractiveness of the surrounding area.
The Future of Green Roofs
Green roofs are slow to gain acceptability due to the higher installation costs, lack of government incentives, lack of awareness and limited research into the benefits. These factors all contribute to the slow growth and popularity of this type of roofing system.
In Germany, the government states that over 12% of flat roofs in that country are green roofs. Although limited in use here in North America and specifically here in the GTA, green roofs are destined to become more popular as building owners, governments and the general public ease towards a greener, sustainable planet.
Contact your local flat roofing specialist to learn more about green roofing.