Friday, May 9, 2008



By Ken Kramer

We all would like to have a little more living space. Why not look to the roof for a truly green building? If, planning a greenroof, it is best to include this in the plans that an architect will prepare for you, or have a structural engineer approve your plans. The roof has to be strong enough to accommodate the extra weight of the greenroof. According to there are two kinds of greenroofs: extensive and intensive. Extensive roofs are more for an ecological cover and are relatively thin. Intensive greenroofs are thicker and are meant for active living; they can have thicker soil and larger plants.

Why would you want a greenroof? A greenroof offers ecological, aesthetic, psychological, and economic advantages. A living green cover on the roof can be an effective insulation from the hot sun, which can make a normal concrete building feel more like an oven than a home. With reduced temperatures from a greenroof, cooling the house will be easier and air-conditioning costs will be minimal. It is certainly more aesthetically appealing to the eye than bare concrete. A living roof can also mitigate stormwater runoff by absorbing water and reducing peak runoff rates to the surrounding storm drainage system. The urban heat-island effect in the concrete jungle is less. Surprisingly the Toyota Company has entered the business, see: and

Every greenroof has the following components:

Waterproofing layer is important for flat roofs. This is often the most expensive component of a greenroof; Root barrier is essential. It can be a pond liner or similar high density polyethylene material sometimes embedded with chemicals to prevent roots from growing through it;

Drainage is important to prevent ponding; Growing media is designed to be light, and weed free, similar to a good potting soil; The plants are selected according to the degree of maintenance and the use of the greenroof. Drought resistant plants are chosen for a relatively maintenance free roof as far as irrigation is concerned. No greenroof is maintenance free, however. A plant with fibrous roots is preferred over those that have taproots. See:

To help you with your greenroof project: London Ecology’s book entitled Building Green: A Guide to Using Plants on Roofs, Walls and Pavements (1993), The Greenroof Projects Database has information from around the world on greenroof projects. We can all strive to make our islands a better place to work and live: Beautify CNMI!

For more information contact: (670) 236-0893; Fax: (670) 236-0899; E-mail: . Website:

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