Post by Robin Koch
Whether you’re wondering why some houses have plants sprouting from their gables, or you’re considering building a living roof on your property, I’d like to point out the benefits of living roofs and show you a few Communitecture has designed. Most of these are not open to the public so please enjoy this exclusive tour.
Firstly, they’re just kind of fun. Creating a living habitat over your head sparks the imagination. When you see a living roof, you may start dreaming of a world where humans don’t destroy an ecosystem with each square foot of development, but live in harmony with other species.
Firstly, they’re just kind of fun. Creating a living habitat over your head sparks the imagination. When you see a living roof, you may start dreaming of a world where humans don’t destroy an ecosystem with each square foot of development, but live in harmony with other species.
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When you see a living roof in your community, you can thank that neighbor for taking responsibility for their impact on stormwater and the urban heat island effect. Since green roofs retain most of the rainfall that hits them--and slow and filter the rest--they don’t make our sewer systems overflow after a storm. In Portland, like many cities, our combined sewer system allows raw sewage to overflow in to the river after a storm. While the city is working to correct this, living roofs can be part of the solution. The urban heat island effect is a result of dark colored roofs and pavement absorbing and then radiating solar heat, throwing the local climate out of balance and making air pollutants more toxic. Rather than heat up the area, living roofs can provide habitat for native birds and pollinators.
Living roofs certainly provide significant benefits for the building owner as well. When a roof is protected from the elements by soil and plants, it often lasts two to three times as long, reducing costs and landfill waste over the life of the building. The additional mass of a living roof protects your interior environment from heat, cold, and noise. Especially on hot sunny days when the roof’s soil is dryer, it significantly reduces inside temperatures. In an urban environment, the sound-dampening quality of living roofs is quite noticeable. At the Hawthorne Hostel, which boasts a living roof over its front porch on a busy street, I’ve been told that simply by not reflecting noise, the living roof makes the bedrooms quieter.
Living roofs certainly provide significant benefits for the building owner as well. When a roof is protected from the elements by soil and plants, it often lasts two to three times as long, reducing costs and landfill waste over the life of the building. The additional mass of a living roof protects your interior environment from heat, cold, and noise. Especially on hot sunny days when the roof’s soil is dryer, it significantly reduces inside temperatures. In an urban environment, the sound-dampening quality of living roofs is quite noticeable. At the Hawthorne Hostel, which boasts a living roof over its front porch on a busy street, I’ve been told that simply by not reflecting noise, the living roof makes the bedrooms quieter.
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Lastly, living roofs are adaptable. They can be modest and endearing to sleek and modern, inviting and inspiring. They can provide a much-needed natural oasis in a bustling urban environment or a place to grow vegetables at home. Living roofs can be designed in many different ways to compliment different architectural styles and serve a variety of purposes.
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So, how is a living roof built? Typically a water-tight heat-sealed membrane is adhered to the roof sheathing. Then a permeable plastic mat and filter fabric are placed on the membrane to provide drainage to the growing medium which goes on it. If the growing medium (or "engineered" soil) is three inches deep or less, it is considered an extensive green roof, which supports sedums and other small plants. Deeper systems are called intensive and can be built to support anything from vegetable gardens to trees, if the building is designed to support them.
If building a living roof, it is important to have it designed by someone with expertise. Rainwater will be retained and sitting on your roof, so it’s critical that the details are designed well to keep water out of the structure. A designer who is well versed in passive solar design is also important, so you get the most benefit from the living roof’s insulating properties. As you can see, Communitecture has overseen the construction of green roofs of many shapes and sizes and on a variety of building types. We love it when our architecture sprouts life and hope to design many more living roofs.
Roofs pictured, from top:
If building a living roof, it is important to have it designed by someone with expertise. Rainwater will be retained and sitting on your roof, so it’s critical that the details are designed well to keep water out of the structure. A designer who is well versed in passive solar design is also important, so you get the most benefit from the living roof’s insulating properties. As you can see, Communitecture has overseen the construction of green roofs of many shapes and sizes and on a variety of building types. We love it when our architecture sprouts life and hope to design many more living roofs.
Roofs pictured, from top:
- Pistils Nursery mixed use building, private roof top garden
- Residential porch roof & brow roof retrofit, attached to original house structure, planted with sedums and native grasses
- Backyard cob sanctuary/meditation room with conical roof of varying slopes
- Backyard cob sauna planted with sedum, prickly pear cactus, and grasses
- Cob pavilion at the Hawthorne Hostel with conical roof and oculus
- Strawbale residence with skylights, planted with grasses
- Pistils Nursery from another angle
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