Steel Construction Vol 40 No 3 - Mining, Industrial, Import/ Export | Page 28

SAISC SUBSIDIARIES: SAMCRA

Site storage of cladding materials
by Dennis White, Director, SAMCRA

The consequences of not protecting
galvanized coated materials stored on
construction sites is relatively well known
to roofing contractors and to a lesser
degree builders. However, there appears to
be a distinct lack of knowledge pertaining
to other materials such as 55% Aluminium/
Zinc (Zincalume, ZINCAL), colour-coated
material, aluminium, stainless steel,
polycarbonate and GRP (fiberglass). The
ingress of moisture between closely packed
components manufactured from these
materials has a detrimental effect on both
their appearance and durability. Damage
can occur within 24 hours.
Initially the clear organic coating applied
to 55% aluminium/zinc will protect the
metallic coating. If the components remain
wet this coating will soften, adopt a milky
appearance and become permeable. This
results in the formation of wet storage
staining followed by corrosion of the steel
substrate. Colour coated material will react
in a similar manner. The backing coat is
only a nominal 5 micron thick.
Aluminium components, including those
that have been anodized, are equally prone
to damage. Items wrapped in plastic are
particularly vulnerable.
The interpretation of what constitutes
protection is as varied as the colours in
a rainbow and mostly inadequate. What
is important is that the components are
stored (preferably inclined) above a dry
surface, kept constantly dry and exposed
to free flowing air. It is of paramount
importance that components exposed to
moisture are separated, dried and exposed
to free flowing air as soon as possible.

www.samcra.co.za

“

Bundles tightly wrapped with waterproof
materials are particularly vulnerable. Where
the covers are draped over the packed
items and anchored to the supporting
surface, they sweat in the heat of the
day. On cooling, the moisture condenses
and is drawn between the tightly packed
components via capillary action. Where
the stacking surface is likely to be
exposed to occasional rainwater runoff,
the gap between the stacking surface and
underside of components should not be
less than 200mm. This will enable any
condensate to be removed by the free
flowing air. Under no circumstances are
cladding components to be stored on
ground with standing water or subject
to ponding. Dunnage used to support
the bundles needs to be dry as moisture
and sap trapped at the interface will
attack the surface of the components.
Dunnage should be spaced at not more
than 2.0/3.0m centres (depending on
bundle mass) and in between individual
stacked bundles in such a manner that the
load is transferred without damage to the
components.
The splayed upstanding ends of bullnosed
cladding are probably the most susceptible
to storage damage. It is common practice
to cover these ends with sealed black
plastic which results in the accumulation
of condensate at the bottom of the curve.
Moisture is not the only reason to protect
cladding materials. The accumulation of
dust, debris and other building materials
such as mortar etc. can damage the surface.
In order to avoid mechanical damage,
cladding needs to be stored out of the way
of other trades and traffic.

“The interpretation of what constitutes protection is as varied as
the colours in a rainbow and mostly inadequate. What is important
is that the components are stored (preferably inclined) above a dry
surface, kept constantly dry and exposed to free flowing air.”

26 Steel Construction Vol. 40 No. 3 2016