When space is a commodity, where can condominium associations put their gardens, their social spaces, even their hot tubs?
“On the roof,” says Jack Carr, licensed engineer and senior vice president of Criterium Engineers in Portland, Maine.
“Roof decks,” he explains, “are getting to be more popular for high end condominiums which want to show off a good view of water.” In his experience, “as associations reach a point of needing to redo roofs, there is more interest these days in adding or redoing an existing deck.”
Daniel Wallace, a landscape architect with Sudbury Design Group in Sudbury, Massachusetts, adds, “Urban landscapes are very desirable to those who are downsizing from their suburban properties, and whether public or private, access to an urban oasis is a great asset in the confines of city living. Owners and associations recognize the value that these spaces offer.” Sean Skapars, owner of Skapars Design Group LLC in Cambridge, Massachusetts, concurs. “In the South End of Boston, roof decks are pretty common, though how we do roof deck gardens is uncommon.”
As Skapars explains, creating a roof deck garden is not a process to be lightly undertaken, precisely because the materials needed must be so lightweight. “Roofs tend to be pretty well constructed and are not necessarily weak, but you have to consider weight. You don’t want to damage the structure, so instead of plopping down huge heavy planters, we custom design and build our own lightweight planters; and instead of gravel, we use foam pellets and light potting soil.” Wallace agrees that weight must be considered and says that “the first step in planning a rooftop deck is to engage a structural engineer to assess structural feasibility. Rooftops are typically only designed to support the weight of historical snowfall. An engineer is required to determine what weight the roof can support and/or what efforts will be necessary to increase the strength of the roof.” Carr concurs, but adds, “Be sure to look into issues of warranties on the roof which may exist. The vinyl roof membrane surfaces may be subject to damage if you put weight onto it, and you need to talk to the manufacturer of the original surface to confirm what can be put onto the roof surface without violating any existing warranties.”