WHAT YOU NEED TO KNOW
How Much Maintenance Is Required?
Green roofs do require regular maintenance, such as removing weeds and checking drains to ensure no water is pooling. Mumford’s company performs maintenance four times a year. “I think a homeowner actually has better roof maintenance as a result of us being up there on a semifrequent basis,” he says. “Otherwise, nobody goes on the roof.”
Where Can I Have a Green Roof?
“Pretty much anywhere but Antarctica,” says Mumford. However, depending on your location, it may be more complex. In drier places, green roofs need irrigation. And in Florida, they must be designed to withstand hurricanes. They’re especially popular in the Pacific Northwest and Canada.
Does a Green Roof Have to Be Flat?
No. They need a slight slope so water doesn’t pool. On pitched roofs they feature retention systems, although they typically aren’t installed on roofs with more than a 40% slope. “At some point, once the angle rises enough, it becomes a living wall instead,” says Mumford, laughing.
Can I Convert My Traditional Roof to a Green Roof?
Yes. But it’s probably going to be expensive because it requires adjusting your home’s structural load capacity. A green roof with 4 in. of soil adds about 30 lbs. per square foot when it’s fully saturated. Don’t forget to factor in the costs of installing green-roof–specific waterproofing and hiring an engineer, as well as the green roof itself.
What Does a Green Roof Cost?
If your house is already engineered to accommodate a green roof, it’ll probably cost $30 to $50 per square foot to have one professionally installed. The range can be as wide as $20 to $200 per square foot, with the high end more likely for an apartment rooftop park with trees, walkways and seating.
Typically, homeowners will put a green roof on only a portion of their house or garage. Mumford estimates a green roof for a two-car garage might run about $25,000. If you decided to cover your 2,500-sq.-ft. house, it might cost $75,000 to $100,000.
Can I Install a Green Roof Myself?
Yes, especially on smaller structures such as a shed. That’s if you have the patience for research and planning, plus a good set of construction and gardening skills. Mumford says to plan on about $30 per square foot, which puts the total for an 8 x 10-ft. shed at about $2,500.
Mumford cautions against installing a green roof yourself on anything bigger than a shed. “You really don’t want to risk your roof caving in,” he says. “It’s just too catastrophic.
And you don’t want a leak. Fixing a leak on a green roof is pretty easy, but finding the leak is another story. If you go for it, call me. Maybe I can coach you through it,” he says.