Steel Construction Vol 40 No 4 - Metal Cladding and Light Steel Frame | Page 10

SAISC TECHNICAL

Are you getting
what you specified?
by Dennis White, SAMCRA Director

You’ve chosen a profile (cladding
system).You’ve selected a material grade
and thickness plus a coating system.
You’ve included all these details in your
specification, so... the cladding is sorted...
right? Not quite.
To an increasing number of entrepreneurs
this is merely an invitation to do business
and let the buyer beware. Specifiers are
particularly vulnerable when it comes to
generic profiles (systems) or copyrighted
brands that have or are in the process of
becoming generic by misuse.
First off you need to understand the
difference between a cladding profile and
cladding system. The profile defines the
geometric shape of the individual lengths
of material whilst a system pertains to the
profile together with the anchoring system
plus all the ancillary items that combine
to provide the waterproof envelope to a
building.
The most common generic components are:
BELOW: 0.58mm Chromodek Charcoal, 26 200m
Klip-Tite sheeting was used to clad the Cell C
Warehouse, an entry in the 2015 Steel Awards.

1) Cladding systems-corrugated (iron), IBR
or box rib and concealed-fix.
2) Grade of material-CQ (commercial

quality) and fullhard
3) Thickness – 0.4 0.45 0.47 0.50 0.53
0.55 0.58 0.60 and 0.80mm
4) Coatings – galvanized, Aluzinc
(Zincalume), colour-coated
(Chromadek), aluminium and stainless
steel.
Theoretically we have a single corrugated
cladding profile available in two widths
8,5/76 and 10,5/75. The 8,5 and 10,5
are the number of pitches between
corrugations and the 76 is the pitch
(distance) between the crests of individual
corrugations measured in millimetres. The
depth is fixed at 18mm (±1mm). In recent
times numerous widths and/or depths
as low as 16mm have been foisted on an
unsuspecting public. There is a noticeable
difference in the spanning capabilities of
18 and 16mm deep corrugated cladding.
IBR was a copyrighted name of a box-rib
(trapezoidal) profile with specific geometry
that was introduced in the 1960’s which has
subsequently become the generic name for
all box-rib profiles. The original profile had
a cover width of 686mm, five ribs spaced
equally at 171,5mm, the ribs were 37mm
deep, 35mm wide at the top and 69.5mm
at the base. Today there are profiles with
much shallower and narrow ribs being
passed off as IBR. Most reputable roofing
profilers produce an IBR that complies with
the original and market a variety of weaker
profiles under various brand names.
It must be remembered that the spanning
capabilities of a profile are directly
proportional to the square of the depth
of the ribs. There have been several
generations of concealed-fix profiles
ranging from narrow standing seams to
trapezoidal ribs or a combination of the
two. Klip-Lok although a copyrighted
profile is trending toward becoming a
generic name (with numerous corruptions
of the spelling) for concealed–fix profiles
with trapezoidal spring snap ribs.

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Steel Construction Vol. 40 No. 4 2016