USG Securock Glass-Mat Sheathing - Manual (Page 4)

Soffit Construction 5.1 The roof must be dried-in prior to the installation of sheathing in horizontal applications.
5.2 Maximum fastener spacing for soffits is 8" o.c.
5.3 Panels are subject to expansion and contraction due to changes in temperature and humidity. The maxi-
mum spacing of control joints shall be 30'. A 1 /
4
" clearance joint is required between S
ecurock
glass-mat
sheathing panels and adjacent walls, fascia, beams or columns. Wings of “L,” “U” and “T”-shaped areas
should be separated with control joints.
5.4 Adequate ventilation in accordance with the local code requirements shall be provided for the space
immediately above the panels.
5.5 Applications must be designed to resist wind uplift.
5.6 Fascia boards should extend at least 1 /
4
" below the ceiling board or adjacent trim moldings, whichever is
lower, to provide a drip edge.
Option 1 Apply a synthetic-type Direct Applied Finish System in accordance with the finish manufacturer’s
recommendations.
Option 2 Embed Sheetrock ® brand paper joint tape in S heetrock ® brand D urabonD ® setting-type joint compound over all
joints. After fill coat has set, apply finish coat of S heetrock D urabonD setting-type joint compound over joints.
Once dry, apply a smooth, uniform skim coat of S heetrock D urabonD setting-type joint compound over the
entire surface of the panels.
After the joint compound has dried, apply one coat of a good quality latex flat exterior primer and finish with
two coats of a balanced, good quality alkyd or latex exterior finish paint.
Control Joints 6.1 The location and design of control joints are the responsibility of the design professional of record.
6.2 Control joints shall be installed at all building expansion/construction joints.
6.3 Locate all other control joints as per cladding system requirements or in accordance with ASTM C-1280
Standard Specification for Application of Gypsum Sheathing, whichever is more stringent.
Cleanup 7.1 Leftover material shall be removed from the job site.
7.2 Waste material shall be disposed of in a safe manner and in compliance with site, local, state and/or
federal requirements.
Exposure After Installation 8.1 USG S
ecurock glass-mat sheathing shall be covered by an exterior cladding or other weather-resistive
barrier and is not intended for long-term exposure. Sheathing shall not be exposed to the elements for more
than 12 months after it has been installed. Immediately upon installing the panels, the joints should be
finished and the entire panel covered with a weather-resistive barrier if the exposure time will be more
than 12 months.
8.2 Apply weather-resistive or water barriers and flashing as required by and in accordance with the applicable
local code requirements and the recommendations of the exterior cladding manufacturer, whichever is
more stringent.
8.3 For maximum protection, the design professional may recommend treating the cut edges with a low-
modulus silicone sealant; treat joints by embedding 4"-wide D
urock ™ exterior tape in a low-modulus silicone
sealant and strike joints flush using a trowel or broad knife. Allow sealant to cure per manufacturer's
instructions prior to installation of weather-resistive barrier and/or cladding system. Note: This treatment
should be used only under mechanically attached weather-resistive barriers and cladding systems.
WB2451/rev. 6-09
© 2009, United States Gypsum Company
Printed in U.S.A.
The following trademarks used
herein are owned by United States
Gypsum Company or a related
company: S ecurock , D urock , USG.
www.usg.com Manufactured by
United States Gypsum Company
550 West Adams Street
Chicago, IL 60661