What is the difference between H4 and H5 timber?

In New Zealand, H4 and H5 are the hazard classes for treated timber used in outdoor applications, including retaining walls, fencing, and other exposed structures. The hazard class indicates the level of protection against biological decay and insect attack.

  1. H4 Timber: H4 is a hazard class that represents timber treated to withstand moderate to high decay and insect attack. H4 treated timber is suitable for ground contact applications such as retaining walls, fence posts, and landscaping structures. It provides a higher level of protection compared to lower hazard classes.
  1. H5 Timber: H5 is a hazard class that represents timber treated to provide a high level of protection against decay and insect attack, particularly in severe outdoor conditions. H5 treated timber is typically used in marine environments, such as jetties, boardwalks, and other structures in direct contact with water or in high-moisture areas.

The key difference between H4 and H5 timber is the level of protection they provide against decay and insect attack. H5 timber offers a higher level of protection and is generally recommended for more demanding applications where there is a higher risk of moisture exposure or in harsh environments.

When selecting the appropriate hazard class for your project, it is important to consider the specific environmental conditions, the level of moisture exposure, and the desired service life of the timber. It is advisable to consult with a timber supplier or a building professional who can provide specific recommendations based on your project requirements and local building codes. Speak to the friendly team at Quality Fencing Auckland to find out more.