Planting a garden on your roof might sound strange, but rooftop vegetation can have a huge positive impact on the environment and on your bank account. A green roof, or living roof, is a roof that is covered in a layer of vegetation.
Plants on a living roof can include sod, flowers, vegetables, succulents, or even trees. To grow a green roof doesn’t just give you something beautiful; they have many benefits that make them an attractive option for large city buildings and small residences alike.
While they have become popular in the United States in recent years, green roofs are not a new idea. They have been an important part of the architecture in Scandinavia for centuries, and have been widely implemented in many European countries since the 1960s. Living roofs are even mandatory on new flat roofs in many countries.
The plants on a green roof can be as simple and low maintenance as a short, heat-resistant ground cover like sedum, or as elaborate as a full-sized park with grass and trees. No matter the size or intended use, living roofs provide amazing environmental and personal benefits.
4 reasons to grow a living roof
1. Living roofs aid water runoff management
Green roofs help reduce the problem of polluted water making its way to waterways and water treatment facilities. Typically, rainwater runs off the roofs of buildings, through dirty city streets, and into the storm drains that carry it to treatment facilities. The water picks up all kinds of pollutants along the way.
The plants on living roofs help slow water runoff and act as a filter, reducing the amount of pollutants that reach storm drains. They also retain much of the water. In summer, the plants on a green roof can retain 70-90% of the water that falls on them and between 25-40% in winter, depending on the plants and depth of the growing medium.
2. Living roofs are energy efficient
Green roofs add an extra layer of insulation to a building. Since the greatest source of heat loss in the winter is through the roof, a green roof helps retain much of that heat. Regular roofs get extremely hot in the summertime, especially if they are a dark color. A living roof keeps the roof cooler, drastically reducing cooling costs in the summer – by over 75%, according to research published by the National Research Council of Canada.
3. Living roofs combat the urban heat island effect
The urban heat island effect is what happens as urban areas develop and changes occur in the landscape. As open land and vegetation are replaced with buildings and roads, surfaces become hot and dry, absorbing and retaining the heat of the sun. Therefore, urban regions become much warmer than surrounding rural areas. This excess heat causes increased energy consumption for cooling, resulting in higher levels of pollution. Hot streets also heat stormwater as it runs over the surfaces, impacting waterways when the water is released back into them.
By covering up black rooftops – some of the hottest surfaces in cities – with vegetation, a huge reduction in the heat island effect is achievable. Much of the light that would otherwise become heat energy is absorbed by plants. Also through the daily evaporation cycle of vegetation, living roofs and walls can cool cities significantly during hot summer months.
4. Living roofs improve the quality of life
In addition to providing a cooler urban atmosphere, green roofs provide a pleasing, natural aesthetic value to homes and buildings. They also create a habitat for birds and other wildlife in areas that were otherwise wiped clean of greenery. In addition, since plants act as natural air filters, they remove many air pollutants and reduce greenhouse gas emissions.
So how do you “go green” on your own roof? There are organizations sprouting up across the US supporting the green roof movement. Many urban areas are promoting living roofs on new construction and often provide education on the topic. A huge variety of planting methods can be used, from rolling sod right onto the rooftop to complex, layered systems with a variety of plants.
The method you choose will vary depending on the size and type of roof you want to plant. You can do a search for information and contractors in your area, or build one yourself. If greening your whole roof seems daunting, try a smaller project first, like the roof of a shed or chicken coop.
Want to see some cool green rooftops people have put on their homes? Check out this studio cabin with a living roof patio and this beautiful shipping container home with a living roof for inspiration!
Like this article? Subscribe to our newsletter to get more great content and updates sent to your inbox!