Green Roof Design - Miami Dade Hurricane Uplift and Irrigation Issues

 Tom Cooper, CEO of Green Roof Solutions, Inc. in Chicago left a comment on a recent post, bringing up several important points.

"We are based in Chicago and agree that irrigated green roofing is not the path to true sustainable construction."

 The Green Roof Industry must move to sustainability.  We as a industry many times 'greenwash' our services and products.  There is nothing worse than a hypocrite.

 Fortunately the living wall industry and green roof business has many sustainable benefits - those we talk about daily here - see the post on plants (green roof plants included) removing cancer causing VOCs out of the air.   Moreover Green Roofs and Living Walls may be the key to Urban Core survival of the green Florida Anole by replacing lost habitat - see a very interesting post and video of the Anole here.  Cleaning stormwater, creating beauty, sequestering carbon, producing oxygen and other positive, eco-centered green roof attributes abound.

I was reading a powerful and inspirational article this morning on MSNBC.com, entitled  "Departing Microsoft visionary sees 'post-PC' world." The message made me think about what we are doing today - and are we looking to the future or caught up in justifying the not-to-efficient present day method of doing green roofs.


Reminiscent of the over-inflated housing market of several years back, I see some of the approaches to green roofing as dangerously similar.


We can all pretend there is plenty of water to go around (as we do with petrol and gasoline) or we can Vision the Future of Green Roofs.  Those who Vision the Future of Green Roofs will lead the way.


Water shortages are catching up with us even now.  Here in Jacksonville we are allowed to water twice weekly and across America we are using up to 50% of our residential water usage for landscape irrigation.  Georgia, Alabama and Florida have recently been involved in bitter legal battles over water supplies.


From a prudent, common-sense point of view, negligence responsibility for adding irrigation to a roof could possible be very expensive if leaks were to develop - even under the best of contract language (I thoroughly enjoyed 'Torts' class in law school and am always 'tort aware' when working with Green Roofs).   In fact, if I were an insurance company I'd want a big fee and strong assurances from the roofer, architect, engineer and more - because a good attorney would be all over the green roof company if irrigation were specified and a leak/mold/damage developed.


I'm sure good water-proof designs are possible but at what cost?  Are we building a 56 Chevy when visioning (considering both cost and sustainability) demands otherwise?


Visioning Green Roofs as Sustainable with nature-irrigated native species is the future.  The industry will be there sooner than later.  Those who lead they way will win the economic prize.

 

"The sedum perennial growers have distorted the market for green roofing by selling 100% cover in modular systems. This type of performance is both rare and unattainable in the long term without irrigation."

 Native Plant species must replace monoculture systems.  Relying on one genus of plants for Green Roofs may cause massive diebacks in the event of a species selective blight or infestation.  My grandmother understood this basic gardening concept - never plant too much of one variety or it may all soon die.


We must watch what plants we put on a roof - See the post from this morning about Exotic Invasive Species.

Good Visioning of the Future for Green Roofs dictates caution about using plants capable of causing native habitat damage. Seeds spread easily.   


Sustainability calls for locale-friendly plant species, preferably native plants.


Interesting articles abound on the varieties of available Green Roof plants.  Sedums have there place however it may not be in Florida or other hot humid areas.  Southern Blight is blight is a big problem for sedums in Florida - due to the hot humid climate, the fungus, Sclerotium rolfsii, may take large, beautiful carpets of sedums on a green roof installed during cooler months and turn them to black, ugly mush during the month of July (if not sooner).  See the post of Southern Blight.

Finally, most sedums generally have very little strength in their roots when compared to other possible green roof plants.  This factor does not bode well for tropical storm situations.

Selecting the right Green Roof plant is important.  Flammability (Volatile oil content), leaf litter, invasive characteristics, drought tolerance and disease resilience, habitat value and beauty are but a few of the factors to be considered.

Monocultures of sedums on roofs in Florida are the result of a lack of Visioning and like the 56 Chevy, wouldn't be sustainable.

"I do have a question for you. How do you propose the State of Florida address codes for the components of green roofing under wind uplift requires such as those for Dade County? DO we design part of the roof to blow off as typical landscaping would yet fix all retention articles to the structure such as edging, ballast pavers for patios and perhaps root barriers?"

Tom - We'll add our thoughts to this next all important question in tomorrow's post.

Love to hear your comments too.

The more we discuss, the more we Vision!

Happy Green Roofing!

As always, feel free to email us here.

Kevin