Green Roofing: How to Build a Green Roof

A green roof refers to the roof of a building which is partially or completely covered by some kind of vegetation. Normally, such buildings possess a waterproofing membrane, above which the plants are grown. A green roof is different from a rooftop garden. The latter consists of plants in containers, which is not a part of green roof system. In a green roof system the waterproof membrane protects the building from water seepage, which can cause damage to the structure. Apart from the waterproofing, this system requires additional layers, for the purpose of drainage and irrigation and also to act as root barriers. Green roofs, which are also known as living roofs, eco-roofs, vegetated roofs and oikosteges, help to absorb rainwater, lower the temperature in cities, provide insulation and also offer a habitat for birds. The term 'green roofs' is also used to denote roofs that use some sort of green technology, like solar panels.

Green roofing is classified as intensive and extensive. This categorization is based on the amount of irrigation required, depth of planting medium, amount of maintenance required, etc. Intensive green roofs require a good depth of soil to accommodate the growth of large plants and lawns. Such green roofs need more labor, power, irrigation, maintenance and plant food. They can house any plants from small trees to shrubs and are easily accessible, like a park. Extensive green roofs are not meant for access, except for the purpose of maintenance. Such roofs require very less maintenance, usually once a year, for weeding or for fertilization. Normally, a thin layer of soil is sufficient for an extensive green roof top. A green roof system can also be differentiated as pitched or flat. Flat ones require more care regarding waterproofing and drainage, as compared to pitched ones, which have slanting roof surfaces.

Constructing a green roof can serve many purposes. Apart from beautifying your roof top, it can also provide insulation and lower temperature and provide many more benefits. You should have a well-planned green roof design, which is best suited for your rooftop. The following are some tips regarding the installation of a green roof.

• The first and foremost thing is obtaining a permit to build a green roof in your building, from the concerned authority. Normally, this is issued by the Department of Construction and Permits. The laws may vary from one place to another and the authorities of some places offer incentives for building green roofs.
• Do some good research regarding the green roof designs and select one which is suitable for your building. You can even take the help of professionals for this purpose. Decide on the type of green roofing (extensive or intensive) and the type of vegetation. It is very important to check whether your building is capable of bearing the load of the additional fixtures. It is observed that some old constructions are not well-equipped to accommodate a green roofing.
• If you are through with the first two steps, the next one is waterproofing the roof. Use a waterproof membrane to protect your building. There is a wide range of materials available for this purpose. You can use asphalt sheeting or specialized rubber sheets which are made for this purpose. Always make sure that the edges are covered.
• After waterproofing, you have to install the root barrier. You can go for concrete or cellular glass, which is good for the purpose of insulation.
• Next is drainage layer. It helps in carrying the excess water to gutters and prevents water retention on the roof. Normally, the drainage layer consists of gravel and pumice.
• Buy some good filter fabric, which can allow the flow of water to the drainage layer, but prevent the movement of soil or growing medium to the lower layer. Usually, polyester or polypropylene is used for this purpose.
• Next, you have to add the growing medium. You can use cleaned top soil mixed with sand or crushed clay and humus. Local soil is also good, but it has a possibility of growing weeds and pathogens. The ideal soil depth is considered to be three inches.
• Now, you can think of irrigation. Drip irrigation is considered to be the best, at least for the first year of installation. This irrigation system is advantageous in saving water, saving your time and is also useful in adding fertilizer.
• It is time to sow the seeds or add the plants. Select those which are suitable for the local climate and environment. Give preference to those plants which are tolerant of sun, wind, frost and drought.

Your green roofing is ready. Don't you think it is easy to install a green roofing system on your roof? You can also take the help of designers who are specialized in this area.