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Timber Frame Glossary

There can be a lot of confusing terminology in the timber frame industry. In general, timber framing is the ancient method of crafting framed structures of heavy timber jointed together with pegged mortise and tenon joints. Lengthening scarf and lap joints can also be incorporated. To prevent lean and racking in a timber frame home or structure, diagonal bracing is used.

Timber Frame

A traditional form of construction using sawn or hewn wood that is characteristically left exposed; joined by mortise and tenon joinery and then fastened with wooden pegs.

Mortise and Tenon

Joined mechanically fastening two separate timbers; the basis of timber frame joinery.


Fasteners that hold timber pieces together, like nails and screws used in conventional framing, or wooden joinery, like pegs used in timber framing


A cross-sectional timber frame wall; bents run perpendicular to the ridge of the roof, while the walls run parallel to the ridge.

Post and Beam

Post and beam home construction is a framework based solely on vertical and horizontal beams. Post and beam structures are constructed in layers, with each floor built independently from the others. Metal brackets are used to connect the beams together.

Structural Insulated Panels

A manufactured panel used in a building shell that offers exceptional, superior insulation and strength. There are a variety of panels with different R-values.

King Post Truss Frames

A common purlin frame style similar to the king post bent truss but with the addition of a tie that breaks the king post. The use of the tie transfers the weight-bearing load to the eave posts, eliminating the king post from below the tie.

Queen Post Truss Frames

Queen post truss timber frames are very similar to queen post bent frames; however, with the addition of a tie that breaks the queen posts the load is transferred to the eave posts. Similar to the king post truss timber frame, the queen post truss frame allows for a clear and open span with no internal posts that affect the floor plan.

Hammer Beam Truss Frames

A common purlin frame style that exerts great pressure onto the eave posts with the inclusion of two hammer beams; similar to a queen post truss frame, with ties that break the post.


A horizontal beam placed part of the way down the rafters, creating a smaller triangle. Ties are used to strengthen roofs and make rafters more rigid.


A frame based on the strengths of joinery and the rigidity of the triangular form.


Eaves are the lower, horizontal edges of the roof that usually overhang the walls of the house.

Eave Plate

Where the roof and walls join to serve as the support for the rafters.

Eave Walls

Are commonly the rectangular walls that the roof rafters are set upon.

Principal Purlins

Longitudinal roof frame timbers that are used between the eave plates and the ridge, supported by internal posts.

Principal Rafters

The main rafter pairs of a bent, which typically support the common purlins.

Collar Tie Frame

A style of frame that has no internal posts and is appropriate for narrower spaces. Collar ties are pieces of timber that span horizontally between rafter pairs.

Common Purlin Frame

A general category of frame; includes any frame type that consists of a series of purlins bearing on principal rafters and often spanning from bent to bent at uniform intervals.

Common Rafter Frame

A general category of frame; includes any frame type that consists of roof rafters that span from the eave walls to a ridge beam, principal purlin or opposing rafters.


The upper edge of a roof formed by meeting rafter pairs, a ridge beam or a ridge purlin. The ridge is at the top of the triangle formed by trusses or where the rafter pairs meet.

Ridge Beam

A horizontal timber that supports the rafter pairs and forms the ridge on the roof.

Ridge Beam Frame

A frame type that uses rafters that span from the eave plates to a central ridge beam or beams. Ridge beam frames have posts located centrally to support the ridge beams.

Scissor Truss Frames

A type of common purlin frame that uses diagonal, crossing ties that span from eave posts to the opposite rafters. The struts of the truss provide a number of advantages: they transfer loads more efficiently to the eave posts, reduce the thrust at the eave wall, and allow for a greater span than rafters alone.

Cruck Frames

A frame type that uses matched, naturally curved timbers that are used to form bents resulting in an organic look. Cruck frames are one of the oldest frame types known. 

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