More and more often these days, you are likely hearing the phrase “living roof” or “green roof.” Though the concept and design of a living roof seems quite modern, the truth is far more complex. In fact, green roofs have been used for thousands of years by societies like the Norse, the Babylonians and the early European pioneers in Canada. So just what is this mysterious, retro roofing composed of? Anything from sod and grass to flowers and herbs. The historical “green roof” was used mostly as insulation; the modern “living roof” is installed both for insulation and as a way to build a more environmentally-friendly home.
Those Crafty Germans and the Living Roof
In the 1970s, many German architects were struggling to maintain and create strong roofing against the strong rain and wind storms that plagued the country. One of the proposed solutions was to install a green roof, whereby the soil and roots of the plants would absorb excess rain water and protect the roofing foundation beneath. The Department of Parks and Recreation in Stuttgart went on to perfect the application of sturdy, hardy plants on rooftops that were not built to hold excess weight. By the 1980s, modern green roof technology was widespread in Germany, but virtually unknown elsewhere in the world.
The Logistics of the Green Roof
There are many different ways to construct a living roof: with a layer of sod; a layer of non-soil substrate boxed in with a frame; multiple plastic or metal substrate containers; or even just by using ceramic plant pots. The variety of plants that can be grown on such a roof are even more varied. As long as the plant species are hardy and able to thrive in the local climate, you can plant just about anything you like on your green roof. Large commercial buildings have gone so far as to plant full trees on their rooftops, while home-owners usually tend to plant simple grasses, flowers and herbs.
Grass, Herbs, Flowers or Vegetables?
Though the basic point of the living roof is to promote environmentally-friendly construction practises and maintain roofs located in wet climates, there is virtually no end to the ways you may choose to use your own green roof. If you have a flat roof that is easy to access via window or patio, why not consider a small vegetable garden? Herbs are another great idea for the inspired home cook. Whatever you decide, it is necessary to provide the garden with everything it needs to grow and flourish: proper soil and fertilizers, drainage systems, and enough root space. For plants that require more than a few inches of root space, you may want to consider ceramic pots or deep potting trays that can be affixed to the base of the roof. Most flowers, herbs and grasses will be just fine with 3-5 inches of substrate.
How is the Living Roof Environmentally Friendly?
A green roof can be considered environmentally-friendly in a number of ways. First, if it is used as roof insulation, it takes the place of processed rubber, fibreglass or other materials whose production has contributed to air and water pollution. Secondly, its use as a home herb or vegetable garden replaces the need for small-scale tilling that could damage local populations of plants, animals and insects. Such a garden also means less dependence on store-bought produce, which has often been treated with chemicals and shipped from hundreds of miles away.