Green Roofs 101 – What is a Green Roof and What Does it Do?

A green roof is one form of Building Integrated Vegetation/Agriculture that is becoming increasingly popular thanks to the many benefits they provide to the building in question. Office and residential buildings, schools and universities, commercial buildings and private homes are all able to have green roofs installed with the proper knowledge and tools. Green roofs can be highly technical and often require professional installation and consultation before proceeding. It’s also a good idea to decide what your main goal is when installing a green roof because they have multiple functions once installed.

Building a sustainable green roof is crucial because without the long-term quality and purpose in mind, the green roof could be a potential for disaster and a lost investment.


What is a Green Roof?

In broad terms, when a roof’s surface is either fully or semi covered in plant life it is called a green roof. This might include rooftop farming, a roof garden, a greenhouse on a roof, or raised bed gardens. However, the actual technologically and professionally installed system used to grow vegetation on a roof is what we will be focusing on. That is to say, the buildings whose owners commissioned the deliberate installment of a fully-automated and high-function living roof with the purpose of providing numerous direct and indirect benefits to the building itself and the surrounding environment.

A green or living roof consists of several components that all function together to maintain it and deliver the various advantages. A waterproof membrane must be installed where necessary so as to prevent water (both rain and re-circulation) seeping into the building. A growing medium is selected which is used to contain the root systems of the various vegetation selected. Stormwater management systems, insulation and vapor barrier layers, and frames and structures are also necessary for creating a functioning, sustainable green roof.


The green roof of the Villa Bio by Enric Ruiz Geli, Spain. Image via Guz Architects.

What Does a Green Roof Do?

Green roofs are multi-purpose but they primarily offer environmental benefits. Green roofs provide insulation for the building, absorb rainwater to mitigate toxic runoff, improve urban air quality, and create natural biodiversity and wildlife habitats in an area that otherwise wouldn’t have them.

Green roofs help lower the building’s operating costs and are a more sustainable option to a traditional roof which would require repair and replacement twice as often. Green roofs can also provide financial incentives through local green initiatives and municipal governments. The City of Toronto’s Eco-Roof Incentive Program offers subsidies for new cool and green roof residential projects.

Green roof technologies can also offer alternative energy sources such as hydro and solar powering the building. In many cases buildings with green roofs grow fresh, organic produce which is either donated or sold locally. All of these factors in the construction of green roofs creates a demand for more green jobs.

Adding natural infrastructure like green roofs is not only popular because of its aesthetic appeal but because when done properly it provides long-term recurring environmental, economic, social, and health benefits for those working and living in the building (and the creatures living on top).

Feature Image: Chicago City Hall’s Green Roof via National Geographic by Diane Cook and Len Jenshe

About The Author

PowerHouse Growers
PowerHouse Growers teaches you how to sustainably integrate urban agriculture into your cities, businesses, and homes. We provide clear solutions and benefits for better health, increased productivity, and lower environmental impact. By connecting you with experts, we bring awareness to solutions that may not be top of mind.