This wood treatment article is from the Wood Protection Association website
Timber is a great material but when used where it
could rot, be infested with insects, wood boring beetles, woodworm,
termites or wood rotting fungi, it should be treated – become
treated timber – to improve its durability by putting it through a
wood treatment plant and treating it with water based preservatives,
copper organic preservatives, creosote preservative, organic solvent
preservative, microemulsion preservative or some other preservative.
It is often good to protect wood more by applying coatings and
coatings can be applied by dipping and immersion or brush or
spraying. This is wood preservation through wood treatment.
Whether you are making a fence, a roof, a timber
frame house, a jetty, a cooling tower, installing joists or a fence
post or a pole for telephone lines or electricity lines, use treated
timber. Timber should be dried or seasoned before wood treatment. The
sapwood and heartwood of timber may need treating with preservatives
and these should be tested against rot and insects including
termites. Wood can also burn so it may need to be protected with
fire retardants or flame retardants. Finally get the correct
treatment of timber with preservatives, coatings, fire retardants or
coatings by referring to standards or specifications.
For more about wood protection visit the Wood Protection Association