Green roofs are environmentally sensitive roofing systems which allow plants to grow on the roofs of your homes or other buildings. There are many benefits to a green roof, including aesthetic and environmental benefits. About fifty years ago green roofs became popular in Germany and have since become trendy in the United States as well. Many cities such as Chicago, Portland and Seattle have started to utilize green roof technology.As a pepper, I am not so much looking for a trendy or aesthetic roof; I am looking for a functional living roof with an added survival or homesteading benefit. I can tell you that building a green roof properly is a process that you need to study, prepare for and execute flawlessly; otherwise you’ll be investing more money to fix costly mistakes.
Benefits
Green roofs retain storm water, thereby preventing runoff and managing floods. They keep heat from escaping and trap dust and pollutants, making you yard just a little healthier. Installing a green roof will also extend the useful life of your roof. The plants and the soil will not allow the UV rays to penetrate and destroy your actual roof (as they do with dead roofs).
Cost
Cost of building a green roof varies depending on the type of system installed, thickness of growth media, size of the roof, types of plants used, and use of an irrigation system.
Considerations
There are several things to consider when building a green roof, such as the slope of the roof, local climate, insurance, and structure. The pitch of your roof should not be greater than 30 degrees but flat roofs are not the best candidates either. Flat roofs have poor drainage which can cause roof damage and damage to the plants. The best slope for green roofs is 1:12. Some local climatic factors that need to be taken into consideration beforehand are wind, sunlight, shade and temperature. These factors will affect what kinds of plants you can plant on your roof and how well they will perform. Another thing to consider before building a green roof is whether your insurance covers green roofs.There are many other things to think about when building a green roof but the last thingI will mention isto check with an architectto see if your roof will support a green roof.
Green Roof Layers
Green roofs have 5 primary layers: your actual roof, waterproof layer, drainage layer, soil layer (also called the “growth media layer”) and the vegetation layer. There are many different options available for each layer. The waterproof layer is the most expensive layer to begin with and I recommend making an investment into a really high quality, heavy duty membrane. When choosing layers, take into consideration the weight of each medium that you choose and consult with a builder or an architect to verify that your choices will not create too much burden for your roof.
Mistakes to Avoid
The primary mistakes you will want to avoid are designs that do not provide proper drainage, herbicides, and surface irrigation. Designs that do not provide proper drainage will drown your plants’ roots and defeat the purpose ofyour green roof. You want to avoid herbicides because the herbicides will leak out of the materials and out into the environment. Lastly, avoid using surface irrigations. Surface irrigations will cause more problems than they are worth. They are expensive to maintain, do not efficiently deliver the water to roots, and lots of water gets wasted through evaporation.
If you’d like to learn more about building a living roof, check out these great books:
- Planting Green Roofs and Living Walls by Nigel Dunnett and Noel Kingsbury;
- Small Green Roofs: Low-Tech Options for Greener Living by Nigel Dunnett, Dusty Gedge, John Little and Edmund C. Snodgrass
To your survival,
Richard Marshall
