Hazard Level Types & Classifications

The timber treatment produced by Davids Timber is treated to specific preservative loading in accordance with Australian Standard 1604.

  • Above ground applications exposed to the elements require a preservative loading classified as H3.
  • Ground contact applications are more severe and require preservative treatment to higher H-4, H-5 and H-6 loadings.

These classes are detailed in AS1604, and the classification is essentially underpinned by studies of fungal attack on timber in various environments.

Hazzard Level Exposure Environment Biological Hazzard Typical Uses
H3 Outside above ground Clear ground, subject to periodic wetting and attack by fungi and insects including termites Decay fungi and insects including termites Decking, Fascia, Pergolas, Carports, Fence Palings and Outdoor tables and chairs
H4 Outside in ground In ground or persistently damp above ground where severe decay and insect, including termite attack may exists. Severe decay fungi and insects including termites Fence post, landscape materials, retaining walls, green houses.
H5 Outside incontact with ground or water For use where high hazard ground contact, fresh water contact and critical end use is involved. Very severe decay fungi and insects including termites Engineered retaining walls, house poles, power poles
H6 Marine Where prolonged contact with sea water exists. Very severe decay fungi and marine borer hazard Piles, boat hulls, jetty post and cross bracing, landings

Interactive treatment guide

The interactive treatment guide below, will assist you to determine the correct Hazard Class for the preservative treated timber in your application. Simply point to the circles on each of the products on and around the house.

Timber Treatment