Green roofs are catching a lot of attention in the eco-conscious media lately. After all, they clean the air, reduce storm water runoff, lower heating and cooling bills and reduce the urban heat island effect. (Oh, and they look nice, too.) But the big question is this: Are they something that you can do at home? That’s a tough one. The answer really depends on the type of commitment you want to make to “greening” up your home.

Chicago City Hall rooftop garden

Chicago’s City Hall has just one of the several intensive green roofs found in the downtown area.

Photo Credit: Courtesy of the Chicago Department of Environment

Chicago city hall rooftop path

The pathway atop Chicago’s City Hall offers a brilliant view of the city…if you can get past the brilliant view of the plants.

Photo Credit: Courtesy of the Chicago Department of Environment

Chicago Center for Green Technology’s rooftop garden

The Chicago Center for Green Technology’s rooftop garden is intensive, but many of its plants are typical of extensive rooftop systems.

Photo Credit: Courtesy of the Chicago Department of Environment

There are basically three kinds of “green roofs.” The first isn’t really a green roof at all, but it can help you take some first steps toward green roof technology. It’s simply creating space for a container garden – usually on a rooftop deck. While not located directly on your roof, it’s still a great way to fight air pollution, help reduce heat absorption and add beauty to your surroundings. (It’s also the least expensive option in green roofs.)

The other two types are extensive and intensive green roof systems. For both of these, the rooftop is actually the garden. Extensive rooftop systems are generally lighter in material and are simpler eco-friendly roof options. Plant material is limited. You’ll typically see a variety of tough sedumss that hold up well to the heat and do well in periods with little rainfall. These guys cover the soil quickly and prevent erosion. In a nutshell, the rooftops won’t look like the lush garden in your back yard, but they still do the tough work that green roofs do best: Make life better for us on the ground.

Intensive roof systems are true gardens in the sky. These beauties have the look and feel of strolling through your down-to-earth garden. Again, you can’t plant just any old species up there, but these gardens can be quite colorful! Because the soil’s deeper on these roofs, they can sustain plants with longer roots. So you might find things like purple coneflower, black-eyed Susan, catmint and prairie dropseed.

As you might suspect, intensive rooftop systems are also the most work and the most expensive. They’re also the heaviest – a big consideration when it comes to any rooftop garden. Any time you add weighty elements to a roof (no matter what kind of green roof you’re putting together), the building’s structural capacity has to be considered. You definitely don’t want your new garden to come crashing down around your ears (or through your roof at all)! In fact, it’s always a good idea to enlist the help of professionals when it comes to adding a green roof to the top of your home. There are just too many factors to consider for most homeowners to tackle this type of project on their own.

I live in Chicago, where green roofs are hot! In fact, the mayor’s office has offered a special grant program to promote the spread of green roofs. In 2005 and 2006, the city awarded a total of $300,000 to help build these special roofs. And there’s always plenty of guidance and encouragement available from the city’s Department of Environment to go green and make the Windy City a healthier place for everyone to live.

Green roof space in Chicago continues to grow. As of mid-2007, there are more than 1 million square feet of green roofs completed, with another 2 million square feet under development. So if you’re looking for a place to see green roofs in action, head to the City of Big Shoulders! Stroll through downtown’s Millennium Park (an entire green roof built atop an underground parking garage) or visit one of the city’s many tall towers and gaze down on all the sky-high gardens in the Loop (like the one atop City Hall).

What it all boils down to is this: Green roofs are a great way to help the environment and save energy in the long run. Whether you’re looking into an intensive rooftop system or just plan to add a few new garden containers to your rooftop deck, you’re helping create a healthier world through plants. And, after all, where else are you gonna garden when you run out of space on the ground?