So, you're finally a homeowner. You've scrimped and saved, and bought the closest thing to a castle that you could afford in a seller's market. Unfortunately, your castle is near a freeway and the earplugs are driving you nuts; and the "feature" you missed hearing from the realtor is that your home turns into an oven during the summer. You don't want to run AC all the time because of the cost and because you're trying to minimize your footprint; but you can't take much more of sitting under a fan in a bathtub of cold water.


What to do?

The shaggy hairstyles that broke through cultural barriers in the sixties are breaking through housing barriers in the naughts. Your house can now sport its own counter-cultural longhaired 'do'; a garden of indigenous plants called a green roof. Green-Roof technology is becoming more affordable and accessible to the average homeowner, and topping your house with a garden can provide a host of benefits - including working to keep you cooler and to insulate against the noises of the world.

Living Roofs

Green-Roofs, or Living Roofs, are vegetated roof covers. Instead of a typical asphalt, shingle or tile roof, a green roof is made of a waterproofing and root-protection layer - so you don't have roots or rains working their way into your bedroom - drainage systems, a lightweight growing medium, and plants. There are a variety of systems that construct green-rooftops, and what system an individual might use may be influenced by the region, the house's existing architecture (like the slope of the roof, or the house's load-bearing ability), the plants that you're looking to use (trees, shrubs, vegetables, or grasses?), and what level of use you wish to make out of the roof. Some green-roofs end up as cultured as English Gardens, and some are reminiscent of the thatched-roofs of the past. Unlike a container garden on a roof, the roof itself becomes the strata on which plants are grown: an important distinction, because the roof as a whole carries the weight of the materials, and the roof itself is responsible for drainage.

Cost & Savings

A green-roof might cost between $ 10-$ 24 US per square foot to install. However, the economic benefits of the green roof offset the initial need for investment and research. It is estimated that a well made green roof will last about twice as long as a regular roof, because the roof membrane - that which waterproofs - is protected by the garden above it. The heating and cooling costs are phenomenal: Karen Liu found in field tests in Ottawa that a 6 inch extensive green roof reduced heat gains by 95% and heat losses by 26% compared to a her reference roofing system.

On top of that, sound insulation is a benefit to the green-roofed home; with 12 cm (almost 5 inches) of substrate, noises can be reduced by 40 decibels. It's a good investment against the annoyances of summer construction and mower noise! At the Franklin International Airport, green roofs were employed successfully along new runways to reduce sound pollution.

Other Benefits

There are also benefits to the immediate air supply around a green-roofed house. Plants create oxygen, absorb CO2, and trap particulate matter from the air, as well as equalizing humidity. Depending on what plants a homeowner chooses, the effect can be quite startling: 17 sq. ft. of grass, for example, can provide all the oxygen requirements for one person for a whole year and remove 0.3 kgs of particulate matter from the air supply.

Cities are getting into the promotion of green-roofing. Not only is there benefit to an individual homeowner, but there are community benefits as well. The urban heat island effect, which causes cities on hot days to be 6 to 8 degrees hotter than the outlying areas, is caused by heat absorption into all that hot black tar and asphalt. This heat effect helps contribute to the production of smog that plagues the busy summer city: substantial green roofing could mitigate such an effect.

The personally enjoyable benefits of increased C02 absorption, particulate matter filtering, air-humidifying, and oxygen production are also beneficial to a community if multiplied over the rooftops of a city. Projections suggest that not only would a green-roofed city be more livable, it would be healthier, with the net effect of lowered health care costs for its citizens who would suffer fewer heat and smog related illnesses. The micro-climate available around green-roofed spaces also may have the added benefit of being a draw to the community, creating spaces which are comfortable to be in even on hot days.

There are big benefits for communities of which an individual green-roofer may not be aware. Storm-water processing is a natural benefit of green roofing - with decreased runoff, a longer run-off cycle, and adding the natural filtration of plants. Some green-roofers work to create irrigation systems with cisterns storing excess runoff to water their roofs during arid summer months, and some use their roofs to create grey-water systems for use in their homes.

Green-roofs also support the maintenance of bio-diverse spaces. A green-roof well planned and planted with indigenous species give birds, butterflies, and other insects a place to visit or nest, returning native habitats to the city.

Germany is the world leader in Green Roof initiatives, with 140 million square feet of rooftops already converted. Toronto is following the German example, offering subsidies of up to $ 20,000 to help convert rooftops (until Oct 15, 2006). However, the green-roof movement is growing; and many cities and municipalities are becoming interested in fostering such climates. A little research might prove existing programs in your area: and a few interested citizens might help start such a program where it doesn't already exist.

Useful Links:

• Greenroofs for Healthy Cities


• Greenroofs.com


• Green Roof Plants


• Northwest Eco-Building Green Roof Project


• Green Roof Industry Association