Having a yard is great, but a lot of us don't have the luxury of extra space in front or behind our buildings. So, imagine all the untapped real estate that could be used to grow flowers, vegetables and even trees — on our roofs. Here's why it's a good idea:
Last week we talked about why replacing your standard asphalt or concrete driveway with permeable paving is good for the environment and your home. Replacing conventional roofing materials with vegetation is good for many of the same reasons:
An Extended Roof Life: A roof covered with all that vegetation will actually last longer than a convential roof, primarily because it's shielded from damaging UV rays. While green roofing might be more expensive upfront, it can have a lower life-cycle cost.
Increased Building Insulation: Whether you use an intensive or extension green roof system, the added layer of soil and vegetation will increase the insulation level of your house, which is important at the roof. It will help keep your home cooler in the summer, warmer in the winter, and thus reduce your HVAC use and energy loads.
Reduced Heat Island Effect: By eliminating the dark asphalt roofing and replacing it with vegetation, you're improving the microclimate of your home and property. Natural materials will help moderate and stabilize their surroundings.
Reduced Runoff: On conventional hard surfaces, such as roofing and paving, water is unable to soak in and runs off, which results in eroded landscaping and overwhelmed storm sewer systems. A green roof is able to mitigate these issues by absorbing, filtering, and cleaning water and air of pollutants. This water can naturally irrigate the plants, and any extra can be collected in a cistern or rain barrel.
Natural Habitat: In addition to creating a place to grow plants, flowers and vegetables, green roofs also provide a great habitat for wildlife, including birds, bees and butterflies.
Check out these posts for more details on types of green roofs and how they work:
• 4 Eco-Friendly Roof Options
• Green Your Drainage: Vegetated Roofs
• How to Shop for a Green Roof
• PlantTherapy: Practical Talk on Green Roofs
• How Do Green Roofs Work?
• How to Start a Green Roof Garden
MORE GREEN ROOFS ON APARTMENT THERAPY:
• Water Not Required: Green Roof Blocks
• Modular Green Roofs
• Living It Up: Rooftop Gardens and Green Roofs
(Image: Ben Rahn/A-Frame via Inhabitat)
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WHOA, big caution here:
You can't just go installing a green roof on existing structure, the added weight of soil, plants etc will have to be considered in the structural design of the building holding it up.
Is this feasible in cold-weather climates with a short growing season (Ontario, Canada)?
You should go into detail on extensive vs intensive green roofs (pet peeve of mine because they are very different roofs). Your photo is of an extensive roof which has less soil and only supports sedum. You can't hang out on this type of roof and the plants don't require watering. Intensive roofs have a thicker soil bed and can support other plants (and maybe trees) but require a structural roof that can support the load and is very expensive. The plants on this type of roof are also typically watered and require water supply at the roof.
Teakfreak, a sedum roof will survive an Ontario winter.
Unfortuately, a sedum roof will not survive an Arizona summer - unless it gets weekly watering.
@DUANE HILL & @TSPINTERIORDESIGN -- yes, it's true, green roofs do need additional engineering than a typical roof, and there are differences between extensive and intensive green roofs. If you click through the links we listed above, you'll see our other posts where we've written about the different types of green roofs and how they work.
Teakfreak, it's very feasible to do a green roof in Ontario. Choose appropriate plants and you're good to go. Look closely at the photo, that's the CN tower in the distance. This house is in downtown Toronto.
I'm pretty sure it's this house:
http://levittgoodmanarchitects.com/project?p=levittgoodmanhouse&c1=residential&c2=None
Thanks, Famous Amos and Duane - I would love to try this. And thanks for pointing out the CN Tower; can't believe I missed it! (Not used to seeing many Cdn postings I guess).
I've always wanted to do this on the roof of my carport for my mid-century modern split level home. I think a bed of grass or some sort of succulent would be awesome.
There's currently gravel on this portion of the roof now - so I'm not sure if the roof could support the weight of plant life. But my even bigger concern is would be the wood timbers that make up the car port roof. I'd be afraid having wet soil up there would cause the wood to want to rot.
In Brasilia in the 70', John Filgueiras,a architect, designed a house with this type of green roof to maintain the temperature inside the home.
http://www.joanafranca.com/lele.html
http://www.google.com.br/search?hl=pt&client=safari&tbo=d&biw=1024&bih=660&tbm=isch&sa=1&q=lelé+filgueiras+casa+dos+arcos+brasilia+nivaldo&oq=lelé+filgueiras+casa+dos+arcos+brasilia+nivaldo&aq=f&aqi=&aql=&gs_l=img.3...26333.33668.0.37625.0.0.0.0.0.0.0.0..0.0...0.0._nmXxHVOavs