Civil Engineering Reference
In-Depth Information
Workmanship
No matter which system of cladding
is used, it must be capable of correct
installation if its performance is to be
guaranteed. Many of the metal sheet
systems are highly sophisticated
designs using combinations of
different materials and skills which
are highly sensitive to error during
fabrication or installation. The
missing gasket separating different
metals, or the wrong type of fixing,
may easily negate months of careful
investigation and design work. These
systems may need specialist skills not
normally associated with
construction, those of general
engineering and metal working being
more appropriate.
Fixing devices should have
sufficient adjustability built in to
cope with all but the grossest of
assembly deviations of the existing
façades. Deviations are often
considerably greater than expected.
The buildings should be measured if
at all possible, but if not, then a total
longitudinal adjustment range of 75
mm will be needed to take account of
deviations within one storey, and
probably as much as 50 mm in
addition will be needed to take
account of deviations over the height
of the building.
Sealants must only be applied in
appropriate weather conditions.
Silicones should not be used against
bare metal because they emit acetic
acid in the curing process.
Inspection
The problems to look for are:
◊
rain penetration into cavities
◊
delamination of bonded thermal
insulation
◊
deterioration of surface coatings on
metal sheets
◊
missing gaskets, especially at cross-
overs and tees
◊
deteriorating sealants
◊
build-up of deposits due to lack of
washing
◊
roll memory in metal sheets
◊
boards not stored flat and dry
◊
noise due to weather conditions
◊
inadequate bonding to lightning
protection
◊
inadequate thermal insulation
◊
inadequate cavity barriers
