Timber in joinery

Date Published

19 August 2022

Document Type





Joinery is the non-structural use of wood and includes windows, doors, cladding boards, skirting boards, door linings, staircases and architraves. It also includes decking components such as decking boards, handrails and banisters, as well as less common items such as timber fins for solar shading. Joinery is known as ‘internal’ for applications inside a building and ‘external’ when situated outdoors.

This Wood Information Sheet (WIS) introduces a number of concepts important to joinery including the related British Standards and the importance of specifying timber which has been supplied and stored at the correct moisture level and installed in conditions which will maintain it at the correct level.


Introduction to BS EN 942
Measurement of dimensions
Moisture content
Specifying timber in joinery
Timber species
Natural durability and wood preservation

Key Information

Timber for joinery (except wood-based panels) may be classified using BS EN 942.

BS EN 942 defines seven appearance classes by defining maximum allowance size for knots and other natural timber features.

External joinery should be treated with a preservative or manufactured from timber which provides adequate natural durability against fungi.

Case studies

The Savill Building is a new visitor centre for the Great Park, the historic 14,000 acre (5,665ha) forest and woodland park to the south of Windsor.

Acharacle is a small and remote community on the south-west tip of Loch Shiel, some 40 miles west of Fort William. For many years the village had campaigned for a new primary school and community space to replace the old Victorian buildings, which were becoming difficult and expensive to maintain.