“What is that? Are those plants?” says anyone pointing upwards and walking up to our front door. Yes, they are plants, about five or more varieties of Sedum. Living with a green roof or live roof presents a few challenges to be aware of before one chooses to have intended plants on the roof. After all this is gardening at the highest level around one’s home.
Part of any remodeling project involves the option for sustainable choices. In the interest of being somewhat mindful of the environment, and to limit erosion due to water run-off, a few years ago, we installed a “green roof.” Others call it a “live” roof. I’ll be honest, the cool factor was what we were interested in.
What is a Green/Live Roof and What Is The POINT? Technically, color has nothing to do with it but live plants mean a live roof. (Our metal roof and those “Lisa Blue” wall panels are also a green choices.) Numerous four-inch deep 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 as a method to decrease erosion. The plants increase oxygen in the air, which improves air quality, which, in turn, aids the environment.
Trays with live plant material sit atop 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 these trays are much less labor intensive and more cost effective. Four seasons later the plants look better than ever. They’ve prospered through sup-zero temperatures and a foot or more of snow. We choose the mix of Sedum based on the the year-round colors it provided, and the trays showed up about 3/4 full of plants, which are now overflowing beautifully
A roof with live plants has the same effect as installing wallpaper, one minute it looks like nothing… and a few hours later the transformation is amazing.
CHALLENGES OF A LIVE ROOF
- Not maintenance free – occasional weeding and fertilizing is required
- Must have proper soil for roof
- Watering may be required
A roof with living plants does require weeding about once or twice a season, because birds like to “drop” seeds of unintended plants. A once a year sprinkle with season long fertilizer helps to keep the plants looking luscious.
The soil or aggregate for a flat roof needs to be different than the soil for a low slope roof. An angled roof requires a soil which holds water considerably more than a flat roof – otherwise the water all runs out and the plants die.
The first couple of seasons dry hot summers required ingenuity, for watering the roof. Spraying the roof from the ground does not work. Fortunately on end of our roof is close to a spigot so up went a hose attached to a soaker hose we pinned to the roof. Not the prettiest solution but thousands of dollars of roof irrigation felt ridiculous. A white hose running up the wall against the white brick proved stealthy enough. This photo is from the day I wrote this post. Compare it to the second photo which is right after installation. Yes, you can walk on it. Just like the Sedum used in garden walkways, it bounces back, but it can be slippery.
Why install? A live roof is 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 roofs which gets at least 6 hours of full sun are the best locations. Load calculations are required too, soil and plants are heavy. Also consider the viewing location, 90% of the fun is seeing the plants on the roof. We see this from inside and outside.
How to install? Hire someone (larger and established commercial roofing contractors are the best). Though simple, this is not a DIY or residential roofing project. Commercial roofing companies have the best experience for flat or low sloped roofs and commercial buildings have the most live roof projects. Choose a contractor who has installed a garden roof before.
Would I do it again? Definitely. The challenges are not difficult, a live roof just requires patience. The plants take a couple of years to completely acclimate and thrive.
For more on some of our green remodeling choices click here.