First of all, what is a green roof? A green roof is a rooftop that is covered with living plants. It is as simple as that. Why would someone choose to have a living roof on their home or commercial building? There are many benefits to having a green roofing system installed on any building. In this article, we are going to explain why it may be the best thing you can do for your home or the building you’re managing.
The Benefits of a Green Roof
Green roofing purifies and reduces rainwater runoff. The reduction of rainwater runoff helps prevent erosion, flooding, and pollutants from being washed into nearby waterways.
They reduce the carbon footprint of the area that they are in by conserving the energy consumption of the buildings on which they are installed as well as directly removing carbon from the air.
Green roofs also last up to twice as long as conventional roofing. The waterproofing membrane that covers the roof is then covered by soil or another growing medium that protects the membrane from UV rays that normally deteriorate the material. This allows the roof to remain watertight and worry free for much longer. Living roofs, when used on commercial structures, can be an asset to the people who work there by providing a green park-like retreat that may increase worker productivity.
Green roof technology can also help urban areas become food independent through roof-top gardening/farming which can be used as a private enterprise or open to the community.
Types of Green Roofs
Now that we have an idea of what green roofs are and why they are beneficial, we can move on to the nuts and bolts. There are three main types of living roof. A choice must be made according to what your structure will allow.
Extensive Green Roof
The first is the extensive green roof. This type is most commonly used on residential structures. It requires the structure to be able to hold 15-25 pounds per square foot. The depth of the growing medium is 3-5 inches. This limits what you can grow, but retains all the other benefits mentioned. At this depth, one can grow mosses, succulents, herbs, and some grasses.
Semi-Intensive Green Roof
The second type is the semi-intensive green roof. This option requires the structure to hold 25-40 pounds per square foot. This gives you 5-7 inches of growing material. This increases what you are able to grow. This depth can support perennials, ornamental grasses, small shrubs and, with added irrigation, some lettuces, greens, and other shallow rooted vegetables.
Intensive Green Roof
The third type is the intensive green roof. This type requires a hardy structure. Many commercial buildings will support the 35-80 pounds per square foot required. This gives you 8-24+ inches of growing media. There are very few limits on what can be grown on an intensive green roof.
Trees, shrubs, and ornamentals could transform the space into a beautiful green park. Any kind of fruits and vegetables suitable to your climate can turn it into a garden or, with enough space, a farm. There have even been examples of wide lawns with putting greens on rooftops in Chicago.
Getting Started with Green Roofs
Green roof construction methods can vary a little but, there are generally 6 layers of material that are added to the roof deck. From the bottom up, those layers are:
- Waterproofing membrane.
- Root barrier.
- Drainage and retention layer.
- A screen-like filter to keep the growing media in place.
- The growing media itself.
Many can make good “Do it yourself” projects. They can be as small as a birdhouse roofs or as large as a warehouse. Some avid pet owners have chosen to add green roofs to dog houses to help keep their pets cool in the summer and warmer in the winter. A green roof on a garden shed can be a beautiful addition to any backyard. When considering a living roof for a larger building, a home or commercial building, inspections and permits are often required. Going with a professional company is highly recommended.
At this point, cost becomes the issue for most. This is easily overcome when the benefits are considered. In all likelihood, the installation of your new green roof will be the last time money will have to be spent on your roof. In the long term, this will save thousands of dollars. More immediately, the savings on heating and cooling will be visible immediately.
The exact amount that can be saved depends on other aspects of the structure. Proper insulation and quality windows and doors will increase the benefits drastically. Most buildings, after having green roofs installed see savings of 10-43 percent, according to a June 2012 report published by the Natural Resources Defense Council and the Emmett Center on Climate Change and the Environment at UCLA School of Law. NRDC Report. This reduction of energy consumption along with the removal of carbon from the surrounding atmosphere have a large impact both financially and environmentally.
Why Are Green Roofs So Important?
Our effect on the environment becomes more apparent every year. Climate change may be the biggest problem we have ever faced. Even with that set aside, no one can deny the impact of our actions. The endangered species list grows longer every year. Pollution in our waterways and the destruction of natural habitat can be seen with the naked eye. The clouds of smog hanging over urban centers like Los Angeles and New York cannot be blamed on naturally occurring phenomena.
Green roofs are a step that we can take that benefits us directly as individuals as well as our neighbors and the environment as a whole. Rooftop community gardens have made substantial impacts on urban communities as a source of food, income, and education.
Green roof technology can reduce the carbon footprint of any structure while actively removing carbon from the atmosphere. On whatever scale it is done, green roof technology works for everyone.