Monday, March 28, 2011

Living Roof on Storage Shed - Cost-Effective, Roof Frame Construction, Green Roof Florida

We have to store plenty of hay for the Urban Farm animals.  The chickens, rabbits, ducks and geese go through quite a bit of hay.

Our hay-bale storage shed is designed aerodynamically to survive high wind loadings.  The structure also provided a perfect opportunity for vertical food production, an opportunity for a lightweight green roof ideally growing some sort of food plant.

The final greenroof design is shown in the photograph here.
Florida Green Roof on Eco-shed - Frame

Rafters are made from electrical conduit, though next time bamboo - a much more sustainable material - will be used to replace the conduit.

Florida Green Roof on Eco-shed - Frame
Rather than using a roofing material like tin, the rafters are covered with farm fencing.  A tarp is strapped to the top of the farm fencing, acting as a waterproofing layer and partial support for the green roof soil and plants.  One of the interesting aspects of the tarp and the fencing is the ability of the tarp to form a small indentation in-between the fencing runs, allowing for water to collect during a rainfall event and acting as mini-storage reservoirs for the roof.

A layer of rough ground organic material such as small branches, bamboo pieces and other bulky material was added to the top of the tarp for drainage facilitation.

Lightweight, high-organic content green roof soil media completed the green roof layer preparation and the pre-sprouted cow-peas added as the final green roof touch.
Rooftop Permaculture Florida Green Roof, Lightweight

We will be posting updates as the peas grow.  Just after one day on the roof it seems like they've already grown several inches!

Florida design code has an interesting concept for tidal surge areas - breakaway systems.  Breakaway systems allow for attached items, such as lattice work to detach in wave action without causing structural damage.  The shed design is similar - though only with respect to natural, lightweight materials.  The palmetto fronds serving as the siding may blow off in a hurricane, but because the shed is made to pipe and fence I would suspect the structure would easily remain.

The same principle applies to the green roof plants.  We've video documented the anti-shear/lift turbulence green roof plants cause in a tropical storm - Tropical Storm Fay.  As cyclone winds whip across the green roof plants turbulence is generated, resulting in a pushing down as well as a pulling up motion, ultimately offsetting and allowing the well-rooted green roof plants to stay in place.

Ultimately, a strong cyclone could possibly flatten everything in its path.

But for cost-effective, inexpensive design, the above concept has provided us with what we believe will be vertical growing space for food, habitat and beauty.

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