A cladding
system designed to accommodate differential movements between an aluminium
frame and metal-faced insulation-cored cladding panels experienced gradual
displacement of building components as the gaskets snaked their way along the
grooves between shuffling panels.
The panels,
being small, elongated less on heating than the relatively long frame
sections. The connection between the two
was a combination of shelf brackets and clamps, with polymer gaskets inserted
tightly into grooves between the panels to complete the weather-sealing. Long continuous gaskets ran horizontally;
vertical gaskets were shorter,
and discontinuous at each horizontal joint.
When the
system heated up and expanded, the panels and vertical gaskets tended to move
upwards. When it cooled, the panels and
gaskets contracted but did not uniformly return to their original positions. The consequence was a gradual displacement of
parts of the system relative to one another.
This opened gaps at the butt joints between horizontal and vertical
gaskets and, in places, drove the vertical gaskets into the horizontal gaskets,
deforming them. Those panels on the
elevations which received most sunshine moved progressively out of alignment.
The design
was intended, by avoidance of rigid fixings, to allow reciprocal movements
without distress. But this lack of
rigidity allowed each reciprocal movement to cause slight relative
displacements in the panels and gaskets, the accumulation of which over time
reduced weather resistance and marred appearance.
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