Timber iQ August- September 2018 // Issue: 39 | Page 30

FEATURES
Wood preservation increases durability and gives extended service life to timber structures.
Lasting preservation
As a natural and renewable building material, timber has undergone
maintenance for centuries. What preservation processes are used
today and how can correct timber treatment extend the longevity of
wooden structures?
By Candace Sofianos King | Photos by Creative Commons
T
imber is the only structural raw material boasting a
truly renewable and sustainable source of supply.
There are timber structures in existence after hundreds
of years of service, but there are fence posts which have
decayed after only 12 to 18 months. Timber is an organic
material that can support the life of other organisms if the
environment is suited to their growth, and under certain
conditions, may lead to rapid breakdown of the wood.
Wood preservation essentially is the science of wood
treatment, utilised to increase durability and give extended
service life. This involves the placement, within the wood
microstructure, of preservative chemicals which are
antagonistic to wood-destroying agencies. Wood
preservation promotes the conservation of indigenous
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forests by making commercially grown plantation timbers,
which aren't naturally durable, effective substitutes for
durable timbers from indigenous forests. It also reduces the
volume of wood used by prolonging the service life of
timber for many years.
According to Bruce Breedt, executive director of the
South African Wood Preservers Association (SAWPA), it’s
necessary to understand the structural form and
characteristics of timber and how this varies from species to
species as these factors determine the extent to which
wood is naturally protected from decay and the ability to
penetrate it with protective chemicals.
See more on page 30