A green roof is a roof which can either be partially or fully covered by plants. It generally constitutes a waterproof covering where vegetation is planted over. The green roof is different from a rooftop garden in the sense that the latter uses containers for the plants while the waterproof covering of a green roof prevents damages to the building’s structure which may be caused by water leaks. A green roof may be called by other names such as vegetated roof, living roof, or eco roof.
For people living in the urban area, green roofs are idea because it helps lower temperature and provide better insulation. Green roof also helps minimize the pollution in your area as plants absorb carbon for their food. Your green roof can also serve as storage for rainwater and provide a habitat for birds and animals.
There are two types of green roofing systems. These are based on the amount of maintenance required; amount of irrigation needed, and required depth of soil for planting. The first is intensive green roof. This type needs to use a depth which can hold large plants when they grow. Intensive green roofs require more irrigation, maintenance, power, and labor.
The other type is extensive. Minimal interaction is intended for this type of green roof. The only reason extensive green roofs are accessed is only for maintenance which takes place usually once a year. The depth of medium used for extensive green roofs are thinner as compared to intensive ones
Procedure for Building a Green Roof
The first step in constructing a green roof is acquiring the necessary building permits from the proper authorities. Check with your local municipality and even your neighborhood’s home owners association. Construction policies may differ depending on where you are located. It’s important to note that some government authorities offer incentives such as tax discounts for building green roofs.
You should have a well thought out plan for your green roof before commencing construction. It would be best to do ample research on the different designs used for green roofs. Pick the one which best suits the roof of your building. You may hire the services of a professional if you are not confident about your designing skills. Decide whether you want your green roof to be the extensive or intensive type. Make sure your roof can sustain the weight of the fixtures you need to install for your green roof.
The next important step waterproofing the roof to prevent leaks. Seal your roof with waterproof membrane to keep your building from being damaged by water. There are numerous materials you can use to waterproof your roof. A couple of the most common choices include asphalt sheeting or specialized rubber sheets specifically designed for green roofs. Make sure all the holes, cracks and edges are properly sealed when the membrane is applied.
Next is installing the root barrier. The best materials used for these are either concrete or cellular glass as they provide good insulation.
The next step is to put up the drainage layer which will lead the excess water towards the gutters to prevent water build up. Gravel and pumice is placed in the drainage layer together with high quality filter fabric such as polyester or polypropylene. This will help ease the flow of water towards the drainage layer and will keep the movement of soil or growing medium into the lower layer.
You should then put up the growing medium of about three inches in depth. Common choices include a mixture of cleansed tops soil and sand or crushed clay and humus. You may also use local soil. However, weeds may grow here and pathogens may be created.
The next thing you should build is the irrigation system of your green roof. The ideal type for start-up green roofs is the drip irrigation system. This can minimize your maintenance time and it uses up only the needed amount of water. Drip irrigation also allows you to add fertilizer easily.
The last step is to plant the seeds or add potted plants. The growth and health of your plants will depend greatly on the climate and environment of your location. This means you need to be very careful when choosing which plants to use for your green roof. Consider the weather in your area.
By following these simple steps, you can now have your very own green roof. Once you assembled your green roof, you will soon enjoy many of its benefits, including better insulation and cleaner air.
Jove,
Being in the green roof business, it is certainly a good thing whenever we see an article promoting the benifits of such and suggesting that an installation should be considered. However, when reading your article I would warn your readers that consideration of the weight of the system alone is not good enough. Taking into account that most engineered soils for a proper green roof installation should have a water holding capacity of an additional 40-50 % of their “dry weight”, this additional weight calculation could be the difference between the green roof growing on the roof or growing on the floor of the building. For example, a typical green roof media would have a dry weight of 48 pounds per cubic foot while the same media saturated would weigh in at 78 pounds per cubic foot, a significant increase.