Vegetated Roofs and Walls Do More than Please the Eye

There’s nothing more pleasing than driving through an established neighborhood and taking in the architectural scenery and the manicured lush landscape. Old homes with vines growing up the walls – it’s all so charming. Even a basic ranch house can look like a million bucks with a creeping fig growing up its walls. Greening a home’s walls improves its visual quality as well as its environmental functioning.

Some people are against this idea. They regard it as a big headache, too much upkeep, or believe the vegetation will destroy their walls. And, in the case of roof and wall greening, there are professionals who are concerned about increased roof loads, problems with leaking, or damage that plants can cause on surfaces. These are all valid concerns. To learn about avoiding these types of problems, look at the extensive research and practices of Europeans. This great book covers the technology behind green walls and roofs: “Planting Green Roofs and Living Walls,” by Nigel Dunnett and Noel Kingsbury.

The greening of urban areas in the U.S. is happening on rooftops and on walls – not just parks – and it’s happening in cities all over the country. A new survey by Green Roofs for Healthy Cities stated that over two million square feet of roof and wall surfaces were greened in 2007, 30 percent more than the previous year. The cities that are leading the way are Chicago, Wilmington, Delaware, Baltimore, Brooklyn, New York, and Virginia Beach.

The Chicago City Hall, greened in 2000, has 20,000 plants of more than 150 varieties from ground cover to trees and shrubs, planted on their 20,300-square-foot roof.

Chicago is a model city in greening rooftops and walls. For the fourth time they’ve topped all other North American cities in the amount of newly vegetated surfaces, according to the Green Roofs for Healthy Cities survey.

In Portland, OR, where runoff harms salmon populations, the building code allows extra floor space to developers when they build green roofs. Other cities across the U.S. are giving tax breaks to developers who demonstrate reduced runoff.

Economic and Environmental Benefits

• Vegetated roofs and walls reduce the urban heat-island effect, making cities more comfortable and easier to cool.
• The added layer of insulation lessens building heating and cooling loads.
• Plants absorb dust and noise, consume carbon dioxide, and produce oxygen. Plants reduce or eliminate rainwater runoff and reduce the danger of flooding.
• With proper design, plants can protect and possibly extend the useful life of the architectural surface beneath.
• Vegetated surfaces enhance biodiversity by providing a habitat for birds and other critters.
• Vegetated roofs can become an enjoyable and harvestable garden for people and improve the cityscape as viewed from high rise buildings.
• Lowered energy consumption in the home or building.

Next on the Greening List – the Walls

In North America greening roofs is much more popular than greening walls. Ivy and other climbing vines are associated with the damage they cause such as pulling away shingles or destroying stucco. The challenge of greening a wall is to design an appropriate wall surface and support structure. There are other considerations too, like choosing the correct plant species to avoid future wall damage and prolong the life of the wall by shielding it from ultraviolet light. By today’s standards the greenery is usually held away from the walls and its effectiveness in cooling, by adding shade, can exceed the effectiveness of roof vegetation in insulating. And, the icing on the cake is improved landscaping on the eyes.

For more information on greening rooftops and walls visit this informative site: Continuing Education Center for Construction