“Green roofs are sprouting up all over!!” “This roof-top garden is really growing on me!!”
…Okay. Now that that’s out of the way…
Thanks to the ambitious extension currently underway at the McCormick Center, Chicago is about to become the city with the greenest roofs with 3 more acres now added! That comes up to a grand total of 5,695,092 sq. feet of green space above street-level. Not bad, Windy City.
Other than making an urban landscape look like Rivendell, roof-top gardens have some amazing powers to make our city look healthy. Even if you’re unfamiliar with the name, you’ve likely been affected by the Urban Heat-Island Effect; the overheating of cities in the summer, which contributes considerably to pollution and increased energy consumption. You already know that green rooftops will help with this issue. Air quality also improves while rain water is retained and cleaned. And if you have a garden on top of your home, it’ll likely be lowering your individual energy bills by absorbing the sunlight that would normally cook your building during our hot summers. The membrane used under the garden will even protect your roof from weather damage, actually making it last longer and require fewer repairs.
Why isn’t every roof a green roof?
The weight of the garden can take a considerable toll on a roof, especially if the building is old or the roof is slanted. It can be difficult and dangerous to get the soil and other equipment to the roof, and many buildings can be held liable for the danger of people walking around on their roof. The supply water to the roof is also a challenge if rainfall is irregular, though if possible, rain barrels can be definitely be used to help irrigation. If you plan on growing plants native to the area, they’ll likely be acclimatized to the photoperiod (daily amount of sunlight) and rainfall of this area, and will do best in these natural conditions. Plants from other climates will take way more work.
If I actually wanted to make one of these things, how would I do it?
Possible layering strategy that can be used.
If your parents/landlords/co-residents are down, you can turn a portion of your roof green and put your property on the map. You’ll definitely need more info than what you’ll find in this blog, but essentially, here’s how they work:
A structurally sound roof is covered with a roofing membrane, which is then covered with a membrane-protecting layer of material.
Insulation is added on top.
A geocomposite material is added for drainage, aeration, water storage, and functions as a root barrier.
NOW you put on the soil or growing material, plant your plants, and establish a care and maintenance routine.
A St. Louis-based company designs and sells “Green Roof Blocks,” which are essentially aluminum boxes with drainage membranes and irrigation hook-ups already installed. You can buy these to simplify garden-building, or install plants in spaces too small for the labor-intensive process described above.
Green Roof Blocks
Where can I go to see one?
Chicago City Hall
For dinner, visit Uncommon Ground, a restaurant that serves its roof-top produce in every dish.
If you want to wander around in one, look no further than our own City Hall on LaSalle Street, or check out The 606, a new park built on disused elevated train tracks on the North Side. You can even use this map to find one close to home. Though you may want to wait until the temperature warms up to venture outside…