Timber products are often treated, chemically altered or coated with hazardous substances. These substances can create a risk of harm to human health or the environment if they leach into the ground and contaminate soil or groundwater.
All waste timber from industrial sources is industrial waste. Industrial waste timber treated with hazardous substances is priority waste.
The general environmental duty applies to the management of treated timber waste from both households and industry.
Classify timber waste
Timber waste is classified differently depending on whether it has been treated or not. This is indicated by paired mirror codes ending in either -H or -NH. The criteria for determining which mirror code to use is set out in Table 1 of the Waste classification assessment protocol.
Treated timber is pre-classified as priority waste under the Environment Protection Act 2017(opens in a new window) and Environment Protection Regulations 2021(opens in a new window), with the mirror code K310-H (timber treated with hazardous substances, including sawdust).
This category is for timber, wood or material derived from wood (including sawdust and engineered wood) that is likely to have been treated, chemically altered or coated with a hazardous substance – including paint, varnish, preservative or fumigant –to enhance the performance of the original wood.
This does not include timber, wood or material derived from wood which has been treated with heat only.
Learn more about classifying industrial waste.
Dispose of treated timber to landfill
This information is specific to disposal of treated timber to landfill.
This information does not apply to:
- resource recovery of waste timber
- managing timber treated with oil-borne preservatives.
When consigning treated timber waste for disposal, you must identify the priority waste category to find out which landfill the waste can go to.
We acknowledge this may be difficult for construction and fencing businesses and contractors. As such, municipal waste landfills can accept treated timber for disposal as industrial waste.
This does not include timber treated with oil-borne preservatives. This only includes:
- fencing
- flooring and decking
- building and construction timber
- furniture and seating
- other timber treated with water-based preservatives or light organic solvent preservatives.
Do not dispose of treated timber waste at solid inert waste (mainly construction and demolition wastes) landfills.
Reuse timber as sawdust or mulch
Under the Environment Protection Regulations, only untreated timber waste can be applied to land in the form of sawdust or mulch.
You should separate treated and untreated waste timber, so far as reasonably practicable. This is so you can make sure treated timber is not present in waste intended for resource recovery – for example, in mulch intended for application to land.
Manage timber treated with oil-borne preservatives
In certain circumstances, timber is treated with oil-borne preservatives (creosote and pigment-emulsified creosote).
This includes treated timber used for heavy-duty construction and in marine environments – for example:
- utility poles
- railway sleepers
- marine piles.
Timber treated with oil-borne preservatives needs further risk assessment to determine which landfill it can go to. This may involve identifying a priority waste category.
If you need more guidance, contact us.
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