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 MIL-HDBK-1001/5A
perimeters and at openings.
Such anchorage serves several
purposes:
a) To prevent stress concentration at flashings, which
could either split or pull loose from their backings and become
vulnerable to puncture. (Loose-laid systems receive maximum
membrane tensile forces at perimeters and other terminations,
according to field strain tests);
b) To restrain contraction in materials subject to
long-term shrinkage;
c)
To reduce membrane wrinkling which can obstruct
6.3
Design Requirements/Considerations
6.3.1
Single-Ply Roofs. For roofs on new facilities (Refer
to Section 10 for reroofing):
a) Require minimum 1/2 inch per foot (4 percent)
slope, 2 inch per foot (17 percent) maximum slope for loose-laid,
ballasted systems.
b) Review material properties, limitations, advantages
and disadvantages, and past performance of all systems under
consideration (check 10-year performance in your geographical
location);
c) Determine wind and fire resistance during this
preliminary survey. Consult Single Ply Roofing Institute (SPRI)
Wind Design Guide for Ballasted Single-Ply Roof Systems Single-
Ply Roofing. Ballasted systems should not be specified in
coastal areas;
d) Check substrate for suitability: for sheet
membranes, suitable substrates are structural concrete (cast-in-
place and precast), lightweight insulating concrete with low
moisture content, plywood, and rigid insulation board; for fluid-
applied membranes, suitable substrates are structural concrete
(cast-in-place and precast) and sprayed-in-place polyurethane
foam;
e) For cast-in-place concrete decks, check concrete
curing agents to ensure compatibility with synthetic membranes.
Some curing agents can cause poor adhesion or even premature
deterioration of the membrane;
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