GreenGuard Synthetic Roofing Underlayment - Manual (Page 2)

2. Installation – Roofing Underlayment (cont.)
D. Around the perimeter of the underlayment, place
roofing nails or roofing nails with a 1 inch plastic cap
approximately 6 inches apart and about 1 inch from
the edge. If the roof covering is to immediately follow
installation of the underlayment, then No. 16 gauge
staples with a minimum 7/16 inch crown may be used.
The fasteners must be long enough to penetrate through
the thickness of the roof deck. If battens are to be
installed over the underlayment, then the underlayment
need only be preliminarily attached pending attachment
of the battens or counterbattens.
E. In the main area of the underlayment, two rows of nails
are used, with the first row placed 12 inches up from the
bottom edge and the second row placed 12 inches down
from the upper edge (the spacing between the two rows is
24 inches). The rows of nails shall be offset so that the nail
in one row is opposite the open area on the second row.
F. Install additional courses of underlayment by overlapping
all horizontal joints a minimum of 4 inches and vertical
joints a minimum of 6 inches. All vertical joints shall
be located at least 6 – 8 inches from vertical joints in
adjacent courses so that joints are staggered.
3. Installation - High Wind Zone/Coastal Areas
A. In high wind zone or coastal areas, the underlayment
shall be installed in accordance with the applicable local
building code. In these areas, decrease the nail spacing
to 4 inches apart on both head and end laps and 12
inches apart in the field areas.
B. In areas with wind speeds in excess of 90 miles per hour,
or wind speeds in excess of 110 miles per hour, the roof
underlayment shall be installed in accordance with Section
1507.2.8.1 of the IBC and Section R905.3.3.3 of the IRC.
4. Installation – Hurricane Zones
A. Considered High-Velocity Hurricane Zones (HVHZ) - the
underlayment shall be installed in accordance with
Section 1518.2 of the Florida Building Code.
5. Installation – Ice Barriers
A. For roofs required to have an ice barrier in accordance
with local building codes, use a self-adhering membrane
complying with ASTM D 1970 or ICC-ES Acceptance
Criteria AC148. The ice barrier shall be installed prior
installation of the roof underlayment so that the roof
underlayment overlaps the ice barrier. See Figure 2.
Figure 1: Installation of Roofing Underlayment
Figure 2: Installation of Ice Barrier Membranes
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GreenGuard ® Synthetic Roofing Underlayment Installation Guide