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Cladding and Curtain Wall Construction 477
Photograph 7.3 Curtain walling with flush silicone sealed joint.
wind forces acting on a glass panel in the face of a building. This straightforward system
of glazing, which needs no spacing, bedding or weathering, has been exploited for the
facility of a flush external glass face interrupted only by very narrow open joint or silicone
sealant gap filling seals between panes of glass. Figure 7.54 illustrates the simplicity of this
system of glazing with panes of glass bonded to a simple aluminium frame, with the joints
between panes of glass silicone sealed. Single or double sheets of glass can be supported
by an aluminium frame designed for fixing to a carrier system or curtain wall grid secured
to the structural frame.
Because of the adhesion of the silicone, both the weight of the glass and wind forces
acting on the glass panel are supported by the metal frame in the illustration of four-sided
structural glazing shown in Figure 7.54. Because of the natural resilience of the structural
silicone bond, some small thermal movement of glass relative to the frame can be accommodated.
Thermal breaks wedged into the frame and bearing on the back of the glass
together with the silicone bond will serve to reduce the thermal bridge at the junction of
glass and metal. The silicone seal between the edges of glass can be run continuously
around all joints. The seal is run on to a backer rod of polyethylene and tooled either flush
with the glass or with a shallow concave finish. The joints between glass faces should ideally
be no more than 20 mm wide.