10/02/07 Green Roof Part 2

Green Roof Part 2. I'm Greg Martin with today's Line On Agriculture. Imagine driving down the street and coming across a home that looked like the roof needed to be mowed! It's an old idea that harks back to the pioneer days when sod homes we're the main dwelling place for farmers and ranchers. The sod roof has grown up and is now one of the ultimate in "green" solutions. A green roof is simply a roof that has plants and other growing materials on it instead of the regular roofing material. But before you start your own green roof project, Patrick Carey with Hadj Design says you need to start with a check of the structure. CAREY: If you think about a normal single family house that has a clay terracotta roof on it or a slate roof on it, that's about the weight of a lightweight green roof. So any structure that is set up for that kind of weight can have a green roof put on it. You can beef up a structure to accommodate the weight of a lightweight green roof. The weights range from 10 to 25 pounds per square foot depending on plants and materials you use to keep it up there. Carey says there are various different systems available for most roof slopes. CAREY: No, there's no limit. You can grow straight up but the steeper you go the more stuff you have to do to resist gravity. Imagine driving down a highway and see a civil engineering project where they have a steep slope and they have that fabric that they staple down in the soil so that you don't have a lot of erosion - that kind of thing is used on green roofs as well. And then as you get steeper and steeper and steeper you might have to put in some sort of structural grid that actually attaches to the roof deck that resist the movement of soil. Depending on the area you live you may have to consider some kind of irrigation system as well. Carey suggests looking around your area at what kinds of plants are native and using them. I live in a high desert area. CAREY: You might go a part of your territory where the plants are growing out of rocks or are growing in very drought environments. You might just go out to an area like that and do a little plant list  what's thriving in that kind of environment and that would be a good beginning to developing a plant list for your area. Of course you are asking yourself&how much for a simple starter system? CAREY: The general range for that kind of installation would be about somewhere between 17.50 and about 22 to about 25 dollars a square foot for the installation and that would include the waterproof membrane, all the geo-textiles, the little retention elements, the irrigation, the plants, the growth media  all delivered and installed. That's a general range. Carey suggests doing lots of research first and to start by visiting greenroofs.com. That's today's Line On Agriculture. I'm Greg Martin on the Northwest Ag Information Network.