Planting a garden on your roof might sound strange, but rooftop vegetation can make 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. This can include sod, flowers, vegetables, succulents, or even trees. These roofs are not just 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 architecture in Scandinavia for centuries, and have been widely implemented in many European countries since the 1960’s. They 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.
Benefits of green roofs
1 – Water runoff management
Green roofs help reduce the problem of polluted water making its way to waterways and water treatment facilities. Typically, rain water runs off the roofs of buildings, through dirty city streets, and into the storm drains that carry it to treatment facilities, picking up all kinds of pollutants along the way. The plants on green 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 growing medium.
2 – Energy efficiency
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 summertime – by over 75%, according to research published by the National Research Council of Canada.