It may seem like a thoroughly modern design idea, something born during the “green” movement by eco-loving hippies. But, actually, throughout history and many cultures, green roofs have often been the norm.
Remember, most people lived in simple earthen homes that were sometimes dug out of hillsides or creek banks. It was only natural that native grasses and wildflowers would flourish on top. Homes with sod or thatched grass roofs, were also susceptible to “invasions” by seeds carried on the wind. Soon every home in the village had a green roof!
Seeking ways to live more harmoniously with nature, modern homeowners are re-discovering the beauty of this kind of roofing. If you are planning to install a green roof, here are some things to consider and keep in mind.
Choosing From the Types of Green Roofs
Before you begin, you need to determine what kind of green roof you want. Here are some of the various types of green roofs.
Extensive Green Roof
Despite the name, extensive green roofs require less maintenance than the other two types. They are nearly self-sufficient, and require maybe an annual weeding or fertilizing. They are not as heavy as other green roofs, since they require less soil. If an extensive green roof is going to be covered with moss, a thin layer of growing medium such as rockwool is all that is necessary.
Semi-Intensive Green Roof
These green roofs require more intensive maintenance—hence the name. Semi-intensive roofs require regular watering, sometimes in the form of irrigation, and regular weeding and fertilizing. In return for the extra work, they offer more variety than extensive green roofs. Shrubs, perennials, and herbs can be grown on a semi-intensive roof.
Intensive Green Roof
This high-maintenance green roofing option offers the most variety of design and flora. Garden paths, rock formations, fountains, and other elaborate additions can be a part of an intensive green roof. Large, flat-topped buildings can even have playgrounds and park-like settings as part of their green roof.
Remember, high-maintenance is not necessarily bad. If you are the kind of person who likes to spend time in a garden—and maybe you don’t have the land to have a regular garden—then an intensive green roof could be a good investment for you.
Planning for a Green Roof
Start With a Green Roof Structure
Soil and sod are very heavy so the first thing you need to do is plan the structure for your green roof. Before you get too far into the roofing project, have a green roof professional determine the strength and weight-bearing capability of your walls. This is especially important if you are installing the green roof on top of your existing roof.
Choosing Plants for a Green Roof
Think about what kinds of plants you want on your green roof. If you want to provide a sanctuary for wildlife such as bees, hummingbirds and butterflies, then plant flowering species. If you are concerned about the surrounding eco-systems and habitats, consider native plantings for your green roof.