We chat with Steven Peck, president of Green Roofs for Healthy Cities, the Toronto-based industry association that supports the North American green roof and green wall industries. He talks about about what goes into a green roof, what’s new in green roofs, and how home owners can find out more about green roofs.

Why Green Roofs

The need for green roofs goes beyond creating more space to garden. Peck talks about the urban heat island effect, which can make urban areas up to 10°C warmer than rural areas.

He explains that the effect is the result of the removal of vegetation—which is replaced by surfaces that radiate heat.

“It’s sort of an outdoor air conditioning, all that vegetation.”

He says that vegetation is like a natural form of air conditioning—and green roofs keep buildings—and the city—cooler.

What’s New in Green Roofs

A lot has changed since Green Roof for Healthy Cities was founded in 1998. At that time, the green roof industry had yet to be developed and policy developed to permit and encourage green roofs.

Peck says that there have been many recent developments in the industry:

There are more companies producing media for green roofs than in the past. Peck explains that green roofs are not made with soil; rather, they use an engineered growing medium, which is designed to drain, be non-compressive, and support plant life.
Modular systems that include a number of components such as the growing medium, a membrane, and edging are becoming widely available.
Some plants used for green roofs are now available in rolls…and can be unrolled much like a roll of sod.

Green Roofs and GROWING FOOD

Peck explains that broadly speaking there are two types of green roof:

extensive green roofs are quite thin, and cover a large area (these are often made with very hardy plants such as sedum)
intensive green roofs have a thicker layer of growing medium and are more like rooftop gardens (these are the sorts of green roofs likely to be used in rooftop food production)

He is seeing more large-scale rooftop food growing operations such as the rooftop garden at Ryerson University in Toronto, and the Brooklin Grange in New York.

“Now we’re seeing a proliferation of rooftop farms.”

For homeowners interested in finding out more about green roofs, Pecks says a first step is usually a structural assessment, to determine what weight a roof can bear.

Some municipalities have incentive programs. For example, Toronto has the Eco-Roof Incentive Program.

Peck says to look for service providers with a Green Roof Professional (GRP) designation. These professionals can be found on the association website.

Connect with Green Roofs for Healthy Cities

The Living Architecture Academy is the online training platform. It has free resources for hobbyists and those interested in sustainability and green space in cities.