null
Understanding Use Class UC4

A logo that states to make sure the wood is UC4 use class 4 treated for ground contact.

Consumer and contract law require that any product offered for sale must be fit for its intended use and a wood product impregnated with preservative is no exception.

An illustration of a tree stump showing heartwood and sapwood in the different parts of the wood.

The minimum standards for the treatment of wood are set out in British Standard BS 8417 and the WPA Code of Practice - Industrial Wood Preservation (January 2021).

In these standards the level of treatment is tailored to the application ‘Use Class’ of a wood product as defined in BS EN 335 (Durability of wood and wood-based products).

Use Class 4 is for end uses where wood is in contact with or very close to the ground and frequently wet.

A table showing the timber components and the penetration requirements after a certain amount of time.

For wood in permanent ground or fresh water contact, or providing exterior structural support, Use Class 4 levels of protection MUST be achieved. Anything less and service life, structural safety and customer satisfaction will be compromised.

A wooden timber post being fitted in a hole in the ground.

What is UC4 Timber user classes? Click here to find out more.


If you would like any further advice on UC4 or other treatments, please contact our customer services team on 01472 907051 and our friendly team will be happy to help.

23rd Jun 2021

Recent Posts