FEATURES
Balau was the timber choice for a beach house in Bakoven, Cape Town.
regularly discuss these options with architects, installers and
their clients to ensure that any selection is appropriate.
Treated South African pine is also a commonly used
softwood option for outdoors, but its characteristic green
stain means that it has limited aesthetic appeal for
prestigious residential and commercial developments.
HARDWOODS
Many tropical hardwoods like Balau (Shorea spp.), garapa
(Apuleia leiocarpa), purpleheart (Peltogyne spp.) and iroko
(Milicia excelsa) are well suited to cladding applications and
are regularly used.
These hardwoods will typically be knot-free and are rated
in Durability Class 1 or 2. Generally they are also harder and
stronger than softwoods, but their additional weight is an
important consideration. They are too dense to be treated
with preservative and are also usually left uncoated. A
surface treatment can be applied if desired, to slow the
natural weathering process, but unfinished is usually
preferable due to the low maintenance requirement.
Temperate hardwoods like European oak (Quercus robur)
and sweet chestnut (Castanea sativa) are commonly used in
Europe, but have not historically been used in South Africa.
MODIFIED TIMBERS
Over the past decade or so, we have seen the rise of a
number of modified timber options – either thermal
treatment or chemical modification. These processes
typically result in greater dimensional stability and
significant improvements in durability of otherwise non-
durable species.
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One of the key areas of focus when
selecting or specifying timber
cladding is its durability.
Thermally modified species available in South Africa include
oak, yellow poplar and pine. Pricing is dependent on species,
but is not dissimilar to tropical hardwood. The thermal
modification process involves the heating of timber which
burns off many of the sugars which would otherwise support
fungal infection or encourage insects. It also darkens the
timber to a rich brown, which fades as the timber weathers.
Special mention should also be made to the traditional
timber treatment technique known as Shou Sugi Ban. This
ancient Japanese method of charring the outer surface of
cladding boards significantly improves the durability of the
boards, as well as providing a striking aesthetic effect as the
charring gives texture and relief to the boards. Depending
on the timber used and the extent to which the charring is
applied, a wide range of effects can be achieved. The
traditional species used for this technique is Japanese cedar,
but it can be used successfully on many softwoods.
WEATHERING AND
INSTALLATION CONSIDERATIONS
Well installed cladding will provide many years of trouble-
free enjoyment. However, we should always remember that
timber is a natural product, and this should be reflected both
in the installation techniques used and the expectations of
the client.
www.timberiq.co.za