While rooftop and plaza pools are spectacular on a warm summer day, they flirt with disaster from a waterproofing standpoint. Just like most people have a deep-seated fear of waterbeds popping in the middle of the night, waterproofers’ nightmares are haunted by the potential for pools leaking over super-expensive suede couches or big-screen TVs. Fountains are similar. Take a common scenario: a pool on a central second floor plaza deck located over a parking garage. While picking and installing a waterproofing membrane was relatively straightforward, little planning went into potential membrane failure or maintenance planning. The swimming pool was constructed without access to the waterproofing membrane under the pool shell. Also, the condo association president’s beautiful V-8 two-seater was conveniently parked beneath. Two years after completion, the condo president began to notice orange-colored stains on his car and traced the dripping back to its origin — a drain pipe over his parking spot.
Stories like these show that fountains and pools over occupied space present a high risk of water penetration, in part because they place a constant and severe performance demand on the waterproofing components. Roofs typically only leak when it rains. Pools and fountains, which are permanently filled with several feet of water, can leak constantly. In many cases, fountains and pools must contain a large volume of water above occupied areas for the lifespan of a building. Despite significant performance demands, we have often seen that the waterproofing design and construction of fountains and pools are given less consideration than other building envelope components. With some extra attention, many problems associated with fountains and pools can be averted by using basic building envelope wisdom, such as redundant waterproofing, use of appropriate materials, proper detailing, logical construction sequencing and simple performance testing.