It’s spring, which usually means rain, and lots of it. Heavy showers can cause cities to flood quickly, and big cities like New York often face major flooding and sewer system runoff problems. One innovative and relatively new way to combat these issues is blue roofs.
Blue roofs are roof systems designed to collect water. Instead of the water immediately running off the roof into the sewer system, it is “managed” via an array of components that could include trays, dams, valves, pipes, barrels and other equipment. Blue roof systems control storm water that’s collected on the roof, and release it into the drainage system at a more regulated rate, helping to mitigate street flooding and sewer runoff issues.
In New York and other large cities, blue roofs are becoming more common because of these benefits.
A blue roof can also work like a cool roof. The water on the roof can act as cooling agent, which can reduce building energy costs and combat the urban heat island effect.
Like any new technology, blue roofs do come with tradeoffs to consider. For example, a square foot of water one-inch deep weighs more than 5 pounds. So, a large area of standing or contained water on the roof (plus the weight of the water management equipment) can add considerably to the load that the roof must handle. Also, standing water increases the potential for leaks, so if you’re thinking about a blue system, make sure that the roof membrane beneath it all is watertight and up to the job. Along these lines, the roof system warranty should explicitly cover “overburden” systems, such as solar panels, vegetative roofs and blue roofing.