In June, SPRI published ANSI/SPRI RP-14, "Wind Design Standard
for Vegetative Roofing Systems." This new standard is intended to
provide a method for designing vegetative roof systems' wind-uplift
resistances. If you are involved with vegetative roof systems, I
encourage you to be familiar with this standard and NRCA's concerns with it.
RP-14 is modeled closely after ANSI/SPRI RP-4, "Wind Design
Standard for Ballasted Single-ply Roofing Systems." Users of RP-14
can determine the maximum allowable wind speeds for vegetative roof
systems based on a specific building's height, roof edge (parapet)
height and exposure category.
RP-14 addresses three specific vegetative roof system designs.
For RP-14's System 1, the installed waterproofing membrane is
covered with No. 4 ballast. For System 2, the roof's field is
covered with No. 4 ballast and the roof's perimeter and corner
regions are covered with No. 2 ballast. For System 3, the roof's
field is covered with No. 2 ballast and the roof's perimeter and
corner regions feature adhered or mechanically...
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