It's a design problem faced in colder cities in North America: people love balconies, but those cantilevered concrete slabs act like radiator fins, sucking heat out of the apartments. (Read more about the problem in TreeHugger here) The cold floors are uncomfortable, can get mouldy and thermal stresses can crack the concrete. In Europe, most building codes demand expensive thermal breaks, but in North America, developers (and purchasers) would rather put the money into granite counters.
That's why this new balcony idea from an Ottawa, Canada company is so interesting. CCI Balconies has developed a prefabricated FRP (fiberglass reinforced plastic) balcony for new construction that weighs almost nothing, virtually eliminates thermal bridging and installs quickly and easily.
You just plop it on your formwork and run the rebars through the plastic ribs; it becomes part of the floor assembly. Then you can build up your cladding right on top of it. The balcony can hold up to 250 pounds per square foot while weight a tenth as much as a concrete balcony, naturally slopes to the outside, is comfortable underfoot and is actually rated as non-combustible construction, being made with fire-retardant resins. In fact, if there is a fire in the apartment below, the balcony top stays cool and comfortable thanks to the insulation inside.
Balconies have been a huge maintenance problem for building and apartment owners over the years; most have been subject to freeze-thaw cycles leading to rusted reinforcing, and have had to be expensively replaced. But there is nothing to rust and there will be no shrinkage cracks happening here; "AirBalconies require very little long term maintenance. The balconies can be repainted with very little surface preparation. You can expect your previous balconies long term service budget to disappear when using AirBalconies."
Aesthetically, it may take a bit of getting used to; seeing it on its own, on the floor of the Construct Canada exhibition, it looked more like a part of a boat than a building. And I am not usually a fan of FRP but hey, in this application it makes a whole lot more sense than a concrete balcony: the saving of the concrete and steel needed to do a cantilever, the light weight, the elimination of the thermal bridge and actually insulating the edge of the slab. This is a real breakthrough.
The balcony is going through its testing at the National Research Council in Ottawa right now; their results are usually respected south of the border so these should be available in the USA soon too, which is very good news for people who care about comfort and energy in buildings. More at CCI Balconies.