Hazard Levels

The best indicator for appropriate use of treated pine is “hazard class” as outlined in AS1604 Timber Preservative-treated-Sawn and round. The type and degree of attack to which timber may be exposed in service is known as the “hazard”. Suitable treatments are defined for each hazard class.

The Hazard Class assigned depends on a number of factors other than insect attack, including temperature, the amount of moisture prevailing in service and the nature and geographical location of the exposure environment. Higher Hazard Class numbers are indicative of a more severe hazard.

Hazard Level Exposure Enviroment Biological Hazard Typical Uses
H1 Inside, above ground Completely weather protected, well ventilated and termite protected Insects other than termites Framing, flooring, interior, furniture and joinery
 H2 Inside, above ground Completely well ventilated and termite hazard may exist Insects including termites Framing, flooring, Interior furniture and joinery
 H3 Outside, above ground Clear of ground, subject to periodic wetting and attack by fungi and insects including termites Decay fungi and insects including termites Weatherboards, rails, cappings, decking, palings
 H4 Outside in ground In ground or persistently damp above ground where severe decay and insect, including termite attack Severe decay fungi and insects including termites Fence posts, landscape material, retaining walls, posts, sleepers
 H5 Outside in contact with ground or water Strength Unseasoned
F14, F17, F22 & F27
Janka Unseasoned
Above Ground
Class 1
In Ground
Class 1
 Engineered retaining walls, house poles, power poles
 H6 Marine Strength Unseasoned
F4, F5 & F7
Janka Unseasoned
Above Ground
Class 1
In GroundClass 2
 Piles, boat hulls, jetty posts and cross bracing, landings

Each Hazard Level is given a rating which starts at H3 which is the most commonly used Hazard Level as it is used in most applications which includes framing for pergolas and decking’s. H4 is used in most in dry in ground applications such as H4 treated pine sleepers. H6 is the strongest of them all and designed to suit extreme moisture and marine conditions.

Davids Timber can supply treated timber to the hazard level as noted in this table.