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Telling the story of 200 years  of White Mountain History

                        Art of Homesteading 3

Post and Beam Construction

Post and beam construction is a very flexible, fast, and strong form of construction. The pieces of the frame can be made ahead of the time, put together like a jigsaw puzzle, and then raised into place.  A building could be almost any size or configuration. Rooms, doors, and windows may be placed anywhere and remodeling is extremely easy with post and beam construction.

Post and beam construction is also called timber framing. Timber framing is the method of creating framed structures of heavy timber, jointed together with various joints. Originally, the lap joint was the most common.  Later pegs were used to create mortise and tenon joints. Diagonal bracing was used to prevent “racking” which was movement of the structural vertical beams or posts. The carpenter would peg the joints with an allowance of approximately an inch; enough room for the wood to move as it seasoned. Then he would cut the pegs and drive the beam fully into its socket.


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Mortise and Tenon

At the heart of post and beam construction are the joints. Every piece of the house frame is joined together using mortises and tenons.

A tenon is a projection on the end of a timber made by cutting away the wood and designed to insert into a mortise, securing the frame.

A mortise is a square hole hammered into the timber to receive a tenon, forming the joint.


         Model Showing  Post and Beam Frame for House or Barn

Parts of the Frame
 The sill is a large beam at the bottom of each wall into which posts or studs are fitted using a mortise and tenon joint.

A joist is one of the horizontal supporting members that run from wall to wall, wall to beam, or beam to beam supporting a ceiling, roof, or floor.

Posts are the main supports at corners and other major uprights.

Plates or Wall Plates are beams located at the top of timber-framed walls that support the trusses and joists of the roof.

Braces are slanting beams giving extra support between horizontal or vertical members of the timber frame.

Trusses are the slanting timbers forming the triangular framework at gables and the roof.

A purlin (or purline) is a horizontal structural member in a roof. They support the loads from the roof deck or sheathing and are supported by the principal rafters, steel beams, and/or the building walls.

The ridgepole is a beam laid along the edge where two sloping sides of a roof meet at the top. It provides an attachment for the upper ends of rafters.



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