What to Know About Green Roofs :: Those are Plants, not Weeds, on my Roof

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“What is that? … Are those plants?” you might say, pointing upwards and walking up to our front door.

Yes, they are plants. About five or more varieties of Sedum.

Part of any remodeling project involves choices and nowadays that includes products that are considered “green”. In the interest of being somewhat mindful of the environment, and to limit erosion due to water run-off, a couple of years ago, we installed what some call a “green roof.”  Others call it a “live” roof.  And okay, I’ll be honest, there is the cool factor too.

What is a Green Roof?

Technically, color has nothing to do with it.  Numerous four-inch garden trays of plants (the Sedum) in a special soil are installed on a roof to capture water that would otherwise fall to the ground or be carried in a gutter eventually beating against the soil below to cause erosion.

The plants increase oxygen in the air, which improves air quality, which, in turn, aids the environment.  They are generally placed on a flat or low slope roof and always with a rubber membrane underneath. (In our case, Firestone 60 mil reinforced EPDM rubber roofing.) There are other planted systems, but the trays are much less labor intensive and cheaper.

Live Roof is also the name of the supplier of the pre-planted garden trays. Um, no, I like to garden but hauling my butt on a roof is not going to happen.  We picked the mix of Sedum based on the the year-round colors it provided, and the trays showed up about 3/4 full of plants.  Yes, I’m anti-red but I’ll live with it as a plant – but it looks gorgeous in the fall and winter.

It had the same effect as installing wallpaper, one minute it looks like nothing… and a few hours later it was done.

Garden trays on ground prior to fall installation.

Maintenance of a Green Roof

Speaking of hauling my butt on a roof. Yes, it does require weeding about once or twice a season.  However, prior to installation I secured an agreement with the husband that he was responsible for any garden tray weeding and the yearly fertilization.  Yes, you can walk on it.  Just like the Sedum used in garden walkways it bounces back.

Verdict after two seasons:  Still cool, however, the slope does necessitate a slightly different soil mixture to better hold water.  In the middle of the summer, it gets very dry in the long days sun. Which brings me to the next part, we are also installing irrigation for July and August.

It is a bit of a pain to stand on the ground and try and squirt the roof.  Without irrigation, the Sedum dies back a bit, though it revives the following spring. Personally, I like the lush, lime green against that blue as long as I can get it, so we’ll be making some modifications.  Next year it will be dripping green plants over the edge!

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Why Install?

Good for the environment and looks fabulous.  Or if you just really want something your neighbors don’t have.

Where to Install?

Flat or low slope roof which gets at least 6 hours of full sun.  Load calculations are required too.  Also consider where it will be seen.  I see this from inside (above) and outside.

How to Install?

Hire someone (larger and more established commercial roofing contractors are the best).  Though simple. this is not a DIY or residential roofing project.

Would I do it again?

Definitely.

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Great project from frequent contributor, Lisa M. Smith aka the Decor Girl. (See all of her posts with us, here.) For more on roofing, and sustainability for that matter, please see those categories, there. For more fun projects, please see our What to Know About series of posts. Cheers. ~jb, editor – BuildingMoxie.com.