Late in 2008, SPRI updated ANSI/SPRI RP-4, "Wind Design Standard
for Ballasted Single-ply Roofing Systems." The updated edition
builds on the standard's 1988 and 2002 editions and includes two
The differences between the 2008 edition and the standard's
previous editions are the addition of a definition for the term
ballast and revision of the description for surface exposure
categories that are used with the standard's design tables.
Also, the following statement has been added: "The Design Tables
are based on the premise that the ballast will not blow off the
roof at the design...
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