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.

The minimum standards for the treatment of wood are set out in British Standard BS8417 (Preservation of Wood: Code of Practice). In this standard, 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 2 is for end uses where wood is used indoors, above ground and within the building envelope, but with an occasional risk of wetting (from plumbing leaks for example).