The dirt on green
roofs
By Michelle
Warren • Bankrate.comForget curb appeal.
Progressive homeowners are interested in green appeal and they're starting at
the top, opting for green roofs designed to save energy and the environment. While
the first thing that springs to mind is a roof-top garden, green roofs are so
much more and less. In essence, they're an extension of an existing roof, however
they include waterproof and root-repellent materials, as well as drainage, filters
and growing matter, all designed to sustain vegetation. While intensive green
roofs have a garden-like feel and can host several different kinds of plants,
extensive roofs are often inaccessible with simple, hardy greenery. Alex
Johnston, administration coordinator for Green Roofs for Healthy Cities, a Toronto-based
non-profit association, says "the modern version of it grew up in Europe,"
but green roofs are gaining momentum in North America; reports show 72 percent
growth in green roof square footage between 2004 and 2005. While the early adopters
are large industrial companies, there's also a residential movement.
"It's something that people are definitely interested in,"
says Johnston. The group's comprehensive web
site is an invaluable source for information and companies that offer green
services. Laura Barker, sales manager for Elevated
Landscape Technologies of Brantford, Ont., says it's possible to green virtually
any size and slope of roof. New technologies, along with record hot summers, rising
energy costs, environmental concerns and a desire to differentiate one's home,
are all giving rise to the green roof movement. "It's growing all the time,"
says Barker, adding that not only are there practical benefits, but "it's
very decorative." She's seen green roofs applied to everything from garden
sheds and gazebos to dog houses. Green
benefits
Earlier this year, Toronto City Council became the first
in North American to adopt a comprehensive set of green roof policies. The move
came after a city-commissioned study by Ryerson University that found if eight
percent of the rooftops in the city were covered with extensive green roofs, it
would generate more than $300 million in initial cost savings in the areas of
storm water management, combined sewer overflow reduction, building energy expenses
and urban heat island reductions. In addition, the city would save approximately
$40 million a year on operational costs.
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Numerous studies outline the benefits of green roofs for: |
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For the
average homeowner grappling with rising energy costs, the insulation factor alone
holds appeal. A typical one-story building with a grassy roof and about 10 cm
of growing medium, for example, would result in a 25 percent reduction in summer
cooling needs, according to Environment Canada. "Many people no longer use
air conditioning after they install a green roof," says Barker. To
green or not to green
Despite increased interest, there are many
misconceptions about green roofs. "A lot of people think
they require a lot of maintenance, which they don't," says Barker. Most extensive
systems need little more than occasional watering, which can be accomplished with
a soaker hose. From there, the level of care depends on the complexity of plant
species. Also, roofs don't have to be flat. The ELT Easy Green
system, for example, adheres to roofs sloping as much as 30 degrees, while the
Easy Green Living Wall system works on steep slopes and even vertical walls. As
for the danger of your roof caving in under the weight, Barker points out green
roofs weigh only about eight pounds per square foot when saturated. Load capacity
isn't a problem in newer homes, but in older Victorians, for example, it can be
an issue. In addition, green roofs have a high-quality membrane
to protect against leaks, and it's been proven that the roofs last about twice
as long as regular roofs because the vegetation offers protection from harmful
UV rays, as well as seasonal heating and cooling, which causes a normal roof to
expand and contract. As a result, while green roofs are more expensive than shingles
(about double the price), maintenance and replacement costs are lower. How
much will it cost?
There are a number of variables that influence
green roof prices, including size of area, depth of growing medium, plants selected,
irrigation and whether a roof is to be accessible or inaccessible. Keep
in mind that intensive systems tend to be the most expensive as they offer vast
possibilities when it comes to plant life and design (they also offer greater
benefits when it comes to insulation and energy savings). Extensive systems are
less expensive as they're a simple covering of hardy sedum designed for the best
drought tolerance and lowest maintenance. The ELT Easy Green system, for example,
ranges from $12 to $20 a square foot, with $12 being about average. Barker
points out users "get (the investment) back in energy efficiency."
There are generally three types of green roofs. A complete
system means that all components, including the roof materials, are an integral
part of the system, while a modular system is positioned above the existing roof;
it essentially consists of trays or containers or plants spread on the roof. Another
alternative is pre-cultivated vegetation blankets. When getting
a quote, make sure it includes not only the system, but delivery, installation,
design and maintenance. Getting started
Arm yourself with your roof's size, slope, load-bearing capacity, drainage systems
and other features, such as skylights. Also take note of climate (you'll want
vegetation that's native to the area and can withstand all types of weather),
sun and wind exposure. Some companies offer do-it-yourself
kits for residential roofs, but when it comes to going green, it pays to first
do your homework and seek expert advice. Michelle Warren
is a writer in Toronto. | 
