Studies performed by NIST's Building and Fire
Research Laboratory often lead to money-saving, safety-enhancing or
efficiency-increasing changes in building practices such as the reduction in the size of
plumbing vents, which saves an estimated $500 per new dwelling. |
Look on the roof of homes built
before the 1970s and you probably will find a pipe about 3 inches (7.6 centimeters) in
diameter poking through and extending up about a foot (30 centimeters) or so. It is a key
venting component of the home's plumbing because it links the closed systems of pipes and
fixtures on the inside to the pressure of the atmosphere on the outside. Without this
connection, everyday happenings such as draining bathtubs or flushing toilets would create
pockets of low pressure in the pipes, which then could either prevent further drainage or
make it easer for waste to build into flow-stopping dams. As
a result of a study done by the National Institute of
Standards and Technology's Building and Fire Research Laboratory, builders now know
they don't have to go through the effort and expense of sticking a three-inch pipe through
the roof. The study, which elucidated details about residential plumbing loads and the
hydraulics of drainage and venting, showed that one-inch pipes would be sufficient and
that the pipes don't even have to penetrate the roof. They can be built within wall
spaces, for example. Subsequent revisions in building codes for single-family dwellings
based in part on the study have led to estimated savings of about $500 per new dwelling
built and a nationwide savings of about $500 million annually, according to the National
Association of Home Builders. |
