- Q.A customer has a building
with a nearly flat roof surrounded by a parapet. The
roof drains to a single scupper, which conducts the
water to a downspout. Ice builds up regularly in the
downspout, and the water backs up and spills down the
wall. What’s the best way to keep the
downspout free of ice?
A.Architect and roofing
consultant Harrison McCampbell responds: No
roof should depend on a single scupper or drain. In
fact, this may be a code violation. Solving this
problem probably requires installing an additional
scupper or drain, and may involve adjusting the
slope of the roof. In addition, the size of the
existing drain opening and downspout may need to be
increased.
If a roof depends on a single drain, and that
drain gets clogged, the result can be catastrophic.
Remember, water weighs over 5 pounds per square
foot per inch of depth. Even 4 inches of standing
water exceeds the live load capacity of most
roofs.