ON 11 June
By: admin
What are Hazard Classes?
In the context of timber, the “H Class” (or Hazard class) serves as a classification system used to indicate the level of treatment to safeguard timber from threats, like decay, termites and fungi. These classifications help in deciding the treatment for timber based on its intended use and the environment conditions it will face. The higher the number in H class, the higher the level of protection.
| Hazard Level | Exposure | Hazard | Environment | Examples of regular use |
| H1 | Indoor use only, above ground | Minimal. Protected from weather and dampness | Well ventilated environments, above ground, protected from rain and moisture | Framing, flooring, interior joinery and furniture |
| H2 | Indoor, above ground | Borers, termites | Protected from rain and moisture | Framing and flooring |
| H3 | Outdoor, above ground, exposed to all weather conditions | Moderate. Decay and insects | Clear of ground, subject to periodic wetting | Decking, fascia, pergola posts (above ground), weatherboard, window joinery, framing |
| H4 | Outdoor, contact with the ground or continually damp | Severe. Decay, insects and sometimes marine borers | Subject to severe wetting | Landscaping material, fence posts, green houses, pergola posts |
| H5 | Outdoor, contact with the ground or freshwater | Very severe. High decay risk and insect attach (borers and termites) | Subject to extreme wetting and leaching and where critical use requires a high degree of protection | Retaining walls, house stumps, building poles |
| H6 | Marine exposure | Extremely severe. Marine borers, decay | Where extensive contact with salt water exists | Piles, boat hulls, jetty post and cross bracing, landings |
Each category indicates a level of risk necessitating effective protective treatments. The right category should be chosen based on the timbers surroundings to ensure its durability and structural strength.
21 Timbers has a large range of timber in stock, coupled with friendly service and advice, we welcome you to contact us and speak with one of our friendly team members on 07 3801 1122 or contact us online today.
