Green Roof Design Considerations

Filed in archive Edge Technology on September 29, 2006

Before you start planting your roof with coconuts or oaks, you have to learn about the two types of green roofs. Remember, knowing which one can spell the difference between having a beautifully incorporated garden or no roof at all.

Types of Green Roofs

There is the Intensive Roof Garden first and foremost. This roof garden is developed for accessibility and intricate landscape requirements. Roofs for intensive gardens must be structurally capable for heavy loads. Soils used here have an average thickness of about 40 centimeters to about 150 centimeters. As such, they require heavy maintenance such as watering, Fertilizing, and others.

The second type is an Extensive Roof Garden. The difference between an extensive garden and the one prior to it is in the weight of the entire garden. Extensive gardens are lighter by design. Planting medium averages about 10 to 15 centimeters and plants are carefully selected to be drought-resistant and rain fed.

Each type of green roof can be put up using any of the many commercially available products and applications. However, there are some fundamental requirements for putting up one.

First you need a waterproof membrane to cover the entire roof structure or slab.

Second you need a Drain mat to drain storm water once the growing medium gets saturated with water. You don't want water to stay in your roof; you want it to go to the drain. Water is the heaviest and one of the most serious considerations.

You need a filter cloth to separate the drain mat from the growing medium. And then you need a growing medium made up of sand, silts, clay, organic matter, and some lava rock for the plants to grow.

Finally you need plants. There are a lot of plant species you can use depending on what your garden concept is.

Remember also that you must consider the sun, rain, wind, and temperature when putting up your roof garden. These are as important as the direction of your roof and its slope.