283757893275

466 Barry’s Advanced Construction of Buildings
Aluminium sheet
composite box panel
Aluminium
subframe
Lattice steel
frame
Neoprene
gasket
Steel vertical of
lattice frame
Lug for
subframe
Subframe
Neoprene
gasket
Subframe
bolted to frame
Gasket fits in
subframes
Aluminium faced composite box panel
with insulation core bolted to subframe
Figure 7.45 Composite box panel cladding.
Thermal
break
Subframe
Insulation
core
Ribbed
aluminium
illustrated in Figure 7.46, allow some equalisation of air pressure between the outer and
inner surfaces of the rain screen, which provides relief of pressure of wind-driven rain on
the joints of the outer lining behind the rain screen. The rain screen will protect the outer
lining system from excessive heating by solar radiation and will protect gaskets from the
hardening effect of direct sunlight.
All wall panel systems are vulnerable to penetration by rain, which is blown by the force
of wind on the face of the building. The joints between smooth faced panel materials are
most vulnerable from the sheets of rainwater that are blown across impermeable surfaces.
The concept of pressure equalisation is to provide some open joint or aperture that will
allow wind pressure to act on each side of the joint and so make it less vulnerable to winddriven
rain. It is not possible to ensure complete pressure equalisation because of the variability
of gusting winds that will cause unpredictable, irregular, rapid changes in pressure.
Provided there is an adequate open joint or aperture, there will be some appreciable degree
of pressure equalisation, which will reduce the pressure of wind-driven rain on the outer
lining behind the rain screen. A fundamental part of the rain screen is airtight seals to the
joints of the panels of the outer lining system to prevent wind pressure penetrating the