WALTHAM, Mass. — 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.

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 Drains.”

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 Force.

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 building location.

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 added.

For more information on this standard, contact SPRI headquarters at info@spri.org or call 781-647-7026.