Joints Used in Post & Beam Construction


Post and beam construction uses many different strong and durable wood joints. Each type of joint requires a high level of carpentry skills; craftsmen use both tools and techniques to ensure quality work. Post and beam joinery is a skill that can be practiced and learned.

Lap Joint

  • A lap joint is used when a beam or post needs to be extended in length. The joint is formed by removing 2 to 3 inches of thickness from the side of the ends that will connect. Each post or beam is then connected by overlapping the next.

Mortise and Tenon

  • Mortise and tenon joinery is used when beams tie into posts from the side at a 90-degree angle. This joint is created by chiseling away wood on the beam end on all four sides, leaving a 2- to 4-inch tenon on the end. A mortise, which corresponds to the size of the beam tenon, is then chiseled into the post that will receive the beam tenon. Mortise and tenon joinery is the most popular method of post and beam construction.


  • Dovetail joints are made by chiseling dovetail shapes in posts and beams. Generally, wood is removed in the shape of a dovetail on the side of a post, creating a pocket. The end of a beam is cut into a mirror-image dovetail shape; the end of the beam then slides into the dovetail notch chiseled into the side of the post. This very strong joint works best to prevent posts and beams from spreading apart.

Tongue and Fork

  • The tongue and fork joint is used to connect rafters at the ridge. One end of the rafter is carved by removing the center of the wood material about 4 inches from the end, creating a fork. The other end of the rafter connector is carved by removing the outside material of the wood about 4 inches from the end, leaving a tongue, which is then inserted into the fork on the other rafter.

Related Searches


  • "The Craft of Modular Post & Beam: Building Log & Timber Homes"; James Mitchell; 1997
  • "A Timber Framer's Workshop: Joinery, Design & Construction of Traditional Timber Frames"; Steve Chappell; 1998
  • "Timber Frame Construction: All About Post and Beam Building"; Jack Sobon and Roger Schroeder; 1984
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