Treated timber

Timber is treated with pesticides to protect it from insects such as borers and termites, as well as fungi that cause rot and decay. These chemicals can potentially be a danger to you, your family, or the environment if they leach into the ground and contaminate soil or groundwater, so it is important to choose as safe a treated timber as possible for your building or renovation project and to use and dispose of treated timber safely and legally.

Most treated timber in Australia is softwood, usually plantation pine. Softwood grows more quickly and is cheaper to produce than hardwood but is not naturally resistant to pests. Treating softwood makes it more durable and versatile. Some hardwoods are also treated.

Treated timber has many uses, including house and deck framing, flooring, building poles, interior and exterior joinery, cladding, garden furniture, trellises, pergolas, picnic tables, exterior seating, patios, decking, lattice, handrails, stairs, retaining walls, poles, stumps, fences and more. It can also be used in fresh water and marine environments.

This 8 minute video contains practical information for treated timber users.

 

The chemicals used to preserve wood are designed to be toxic to pests.  Some can harm people if not handled properly, or the environment if they leach into the ground and contaminate soil or groundwater. So it’s important to select the right timber for the job and to always choose the least toxic alternative.

People may be exposed to the chemicals in treated timber when

  • using it in their workplaces or homes
  • coming into contact with ash or smoke after treated timber has been burnt.
  • inhaling sawdust when using power tools on treated timber
  • having contact with soil which has been mulched with treated timber woodchips or sawdust

One preservative, copper chrome arsenate  (CCA), may harm people or the environment if not handled or disposed of properly. CCA contains arsenic, which causes cancer. Timber treated with CCA must be labelled correctly and must not be used in

  • playgrounds
  • picnic areas
  • areas where people regularly come into contact with treated surfaces

When choosing a timber treatment, consider the location, the type of pests or fungi the timber will be exposed to, and the purpose of the final product.

Treated timber that is less toxic than CCA includes

There are also timber alternatives which are naturally resistant to pests and decay. These include

  • some hardwoods
  • cypress pine
  • plastic, aluminium, concrete or other composite ‘wood-look’ products, although these have a larger carbon footprint than timber

Before you buy, handle or work with treated timber

When you have finished, you need to properly dispose of any waste treated timber.

If treated timber is already in place it should be handled correctly.

  • Sometimes it is difficult to know which timber preservation method was used. If you cannot identify it, play it safe and handle it as if it is copper chrome arsenate.
  • Do not put food in direct contact with treated timber. Use a table cloth.
  • If food has been in contact with treated timber, it should be washed or thrown away.
  • Do not use run-off from treated timber for drinking water.
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