Module: Timber connections Unit: Carpentry joints

Date Published

20 August 2022

Document Type




In many respects, timber is an ideal building material but because of its anisotropic nature, joints have to be carefully considered. The strength of a connection is usually determined by the timber properties in the weaker direction (perpendicular to the grain) in compression, shear or tension.

Carpentry joints were first developed for use in medieval frames. However they are still used in restoration, reproduction work and modern buildings that use traditional forms.

Generally these structures originally used oak or chestnut, but for the pegs unseasoned ‘green’ timber was used.

Key Information

Timber connections, such as carpentry joints, have limited tension and moment capacity. Therefore most connections are configured to transfer compression and shear forces only.

Carpentry joints mainly fall into three categories: mortice and tenon joints, lap joints and scarf joints.

Case studies

Built: East is a public pavilion, by OGU Architects and Donald McCrory Architects, that brings together both historical and present-day manufacturing innovations of its East Belfast location.

Walking into the new railway station at Abbey Wood, the immediate impression is of the elegant timber roof which arches over the interior, imparting a warm, natural quality to this large public space – more than 25 metres by 25 metres.