10/02/07 Green Roof

Green Roof. I'm Greg Martin with today's Line On Agriculture. I have always been fascinated by the old thatched roofs in Europe. Something about putting a natural material on the roof has always appealed to me. Now it appears the old way of thinking is coming of age. Patrick Carey is the Architect Editor for Greenroof.com and works for Hadj Design in Brier, Washington. CAREY: Well a green roof is basically vegetation on a roof, plants instead of shingles. The idea is that a vegetative surface has a lot of advantages over a surface that is made out of what you normally see on a roof; everything from retention of storm water to prevent combined sewer over flow, having storm sewers backed up. It's like putting a sponge on your roof. It absorbs rain water; it holds it for a while and then releases it slowly. There are also great insulating properties from a green roof in addition to many other advantages. CAREY: There's about 20 documented advantages to green roofs, everything from producing oxygen to sequestering carbon to reducing the cooling load on a house. It keeps the house cooler in the summertime without making it colder in the winter. It increases the lifespan of any membrane or any roofing material underneath it by about 2 ½ to 3 times. That means not having to replace your shingles as often&if ever and that can keep a large amount of roofing materials out of the city land fill. And if you are a nature lover wanting to help preserve the environment& CAREY: It allows for a certain amount of habitat, for plants and animals that are at danger at ground level because of foot traffic, human activity, developments. But one of the main things that really inspires a lot of people about it is below the footprint of any building is nothing but dead soil and this is a way to pay back Mother Nature for the parking space. It's a way to reforest the built environment and as we become more and more densely compacted population of people in urban centers which is where the vast majority of people are living now, green space in those areas is becoming increasingly precious. Green roofs are not just for business buildings. Residential homes can have a green roof as well but you can't really just start throwing dirt up on your roof and toss out seeds and hope to have a green roof but that is the basic idea. CAREY: You should be a little bit more scientific than that but sometimes for experimenters and first adopters, people take that on. But the short answer to your question is yes, we've done 30 residences; steep slopes, flat slopes, lightweight, fairly heavyweight. Tomorrow we are going to look more at the weight issues plus design and installation of a green roof. Be sure and go to greenroof.com for more information. That's today's Line On Agriculture. I'm Greg Martin on the Northwest Ag Information Network.