Exposed or semi exposed concrete
balconies and concrete stairways may be subjected to the sheeting
effects of stormwater and may spall as a consequence of moisture
penetration.
This spalling is commonly referred to as "concrete cancer"
which may also lead to rusting of the reinforcement steel within
the body of the concrete. Damage of this nature can lead to a weakening
of the support capability of the concrete. If the concrete serves
as roofing over internal living spaces, damage to internal ceilings
and internal walls may result from continuous leakage. Concrete
balconies subject to moisture penetration should have the spalling
concrete removed, the structural steel damage treated and the concrete
replaced with suitable material, appropriately finished. The surface
of the balcony should be sealed with a protective finish or membrane
sheeted to guard against further moisture intrusion.
Timber framed balconies with moisture penetration need to be reconstructed
to enable the subsequent waterproofing membrane to fully conform
with AS 3740 "Waterproofing of wet areas within residential
buildings".
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