2 0 1 3 P R O D U C T G U I D E VIRACON PRODUCT GUIDE 2013 ...

glazing guidelines
Glazing guidelines
Viracon specifies that 100% silicone setting blocks be used for all types of glazing systems. The blocks should have a Shore-A
durometer hardness of 85 ±5. They should also be centered at quarter points and be 1/16” (1.6 mm) less than the channel width
(See Figure 1). For additional recommendations, contact the appropriate gasket or framing manufacturer.
Viracon specifies that edge blocks or anti-walk blocks be used for dry glazed systems. Viracon also specifies that edge blocks
be silicone and have a Shore-A Durometer hardness of 60 ±5 and be a minimum of 4” in length. They should be installed in
the vertical channel with a 1/8” (3mm) clearance between glass edge and block. This will limit lateral movement of the glass.
Inadequate edge clearances can cause glass breakage as a result of glass-to-frame contact. For recommended face and
minimum edge clearances, as well as minimum glass bites, (See Figure 2).
WEEP SYSTEM
The edges of laminated, insulating, and spandrel glass
should not be exposed to water or moisture vapor for
extended periods of time. Exposure of the glass to moisture
vapor or liquid water for extended periods will ultimately
result in seal failure, coating deterioration, sealant
deterioration, or de-lamination. Viracon requires either
a positive weather seal, or an adequate weep system to
prevent this occurrence (See Figure 3). The effectiveness of
the weep system or weather seal depends on the design,
workmanship, engineering, and mock-up verification testing
completed by the glazing manufacturer, installer, or designer.
Responsibility for the weep system and its performance is
the responsibility of those parties or others, and is not the
responsibility of Viracon.
Weep
System
FAce
Figure 1
Setting
Blocks
Structural silicone glazing
Structural silicone glazing uses silicone sealants with an
interior backup mullion. It must be specified as a structural
silicone glazing system due to compatibility limitations of
silicone sealants with certain types of glass or insulating
unit secondary seal designs. To obtain approval for any
structural silicone glazing system, contact the appropriate
silicone manufacturer or the Technical Services Department
at Viracon.
Bite
EDGE
closed-cell
neoprene
gasket
Figure 2
dense
wedge
gasket
Weep
Figure 3
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