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Timber frame glossary

The name of each piece, where it is, and what it does. Both sketches are drawn by the generator.

Sobon's frame (Beemer) — common rafters

STRUCTURE SUJETTE À L'APPROBATION D'UN INGÉNIEUR EN STRUCTURE (P.Eng. au Canada, Professional Engineer aux États-Unis). Ce document ne remplace ni un calcul ni un sceau. STRUCTURE SUBJECT TO APPROVAL BY A STRUCTURAL ENGINEER (P.Eng. in Canada, licensed Professional Engineer in the United States). This document replaces neither an analysis nor a seal. 12345678910
  1. Sill — The timber laid on the foundation. It takes the post feet and carries the floor joists.
  2. Joist — Floor member spanning sill to sill. It carries the floor and nothing else.
  3. Post — Vertical member. It takes down to the ground, in compression, what the roof and plates give it.
  4. Girt — Horizontal between two posts in a wall. It holds them at mid-height and takes the wall infill; it does not carry the roof.
  5. Door post — Short upright framing an opening; it carries the door girt.
  6. Brace — The short diagonal between a post and a horizontal. It keeps the frame from racking: without diagonals, a pegged frame has no sideways stiffness.
  7. Wall plate — The horizontal at the top of the wall, post to post. Rafters sit on it; it carries the roof between bents.
  8. Tie beam — The bottom member of the bent, wall to wall. It TIES the spread: under snow the rafters push the walls out, and the tie beam, in tension, holds them.
  9. Common rafter — Sloping roof member, in pairs meeting at the peak. It carries the roofing and snow.
  10. Collar tie — Horizontal between two rafters, high in the roof. It keeps them from bending. ⚠ It is NOT a tie: it does not replace the tie beam.

A Chappell frame — king post, purlins and central beam

STRUCTURE SUJETTE À L'APPROBATION D'UN INGÉNIEUR EN STRUCTURE (P.Eng. au Canada, Professional Engineer aux États-Unis). Ce document ne remplace ni un calcul ni un sceau. STRUCTURE SUBJECT TO APPROVAL BY A STRUCTURAL ENGINEER (P.Eng. in Canada, licensed Professional Engineer in the United States). This document replaces neither an analysis nor a seal. 12345678
  1. Interior post — Post in the middle of the building. It cuts the tie-beam span and takes the load to the ground, on its own footing.
  2. Central beam — Beam along the building, under the middle of the tie beams, on posts.
  3. Tie beam — The bottom member of the bent, wall to wall. It TIES the spread: under snow the rafters push the walls out, and the tie beam, in tension, holds them.
  4. King post — Vertical at the middle of the bent, standing on the tie beam. It carries the ridge; with struts, it hangs the tie beam (and is then in tension).
  5. Strut — Diagonal from the king post foot to mid-rafter: it shortens the rafter span. It blocks the attic; it can go if the rafters are sized up.
  6. Principal rafter — Heavy rafter at the bents only. It carries the purlins.
  7. Purlin — Roof horizontal from bent to bent, on the principal rafters. The decking is nailed to it.
  8. Ridge beam — The horizontal at the peak, from bent to bent.

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