America’s first national standard for retrofit roof drains, developed by SPRI in 2004, was re-approved by the American National Standards Institute (ANSI) in December 2009.
first national standard for retrofit roof drains, developed by SPRI in 2004,
was re-approved by the American National Standards Institute (ANSI) in December
The revised RD-1 standard was re-approved as required by
ANSI’s policy that all National Standards be re-evaluated every five years. The
standard is designated ANSI/SPRI RD-1, 2004, “Standard for Retrofit Roof
SPRI, the association representing sheet membrane and
component suppliers to the commercial roofing industry, developed this roof
drain standard to fill the information void regarding retrofit drains.
“Retrofit drains that meet this standard have proven to
perform at the high level demanded by designers and building owners,” said Stan
Choiniere, task force chairman of SPRI’s Retrofit Roof Drain Standard Task
The main differences between retrofit drains and new ones,
Choiniere noted, stem from the need to place them where existing drains already
are installed. This means that capacities must be checked and the connection to
existing plumbing must be leak-free.
Retrofit drains, by their very nature, have smaller drainage
diameter than the original drains because they must fit inside the existing
plumbing. Assuring sufficient capacity depends upon the retrofit drain
diameter, the number of drain sites and the rainfall expectations for the
Therefore, the retrofit roof standard, ANSI/SPRI RD-1,
features a test protocol designed to assure a leak-free connection to existing
piping. Also included are methods intended to calculate sufficient drainage. An
Isopluvial map (Rainfall Rate Map) of the continental U.S. shows maximum one-hour
rainfall values with a 100-year return rate.
“SPRI continues to maintain its current standards following
the ANSI process and also has several new standards in development,” Choiniere
For more information on this standard, contact SPRI
headquarters at info@spri or