What Is a King Post vs. Queen Post Truss?
A king post truss has a single central vertical member (the king post) connecting the roof peak to the tie beam — the simplest traditional truss, spanning up to ~25 feet. A queen post truss has two verticals (queen posts) dividing the span into thirds — spanning 25-40 feet with greater efficiency. Both are timber-framing classics still used in exposed-structural architecture and porch roofs.
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King post truss
The triangle: two top chords (rafters) meeting at the peak, a horizontal tie beam across the bottom, and the king post in tension hanging the tie beam's midpoint from the peak. The king post is in tension (it hangs the tie beam up); the top chords are in compression; the tie beam resists the outward thrust. Simple, beautiful, and limited: beyond ~25 feet the tie beam sags and the top chords get unwieldy.
Queen post truss
Two queen posts divide the tie beam into thirds, each hung from the top chord by the roof slope geometry, with a straining beam between the queen post tops. The subdivided panels shorten the effective spans: the tie beam spans third-points instead of full span, the top chords span shorter segments. Result: 25-40 foot spans with reasonable member sizes. Add diagonal struts and the family extends further (king post with struts, queen with princess posts).
Modern use and engineering
Exposed trusses in great rooms, lodges, churches, and restaurants — where the structure is the architecture. The engineer designs the joinery (mortise-and-tenon, steel knife plates, or through-bolts — the connections are the engineering), sizes members for the actual loads (not the historical rules of thumb), and details the tie-beam thrust restraint. Timber truss analysis follows the same statics as steel; the material properties and connection behavior are the specialty.
The bottom line
King post = one central vertical (to ~25 ft); queen post = two verticals (25-40 ft). Both hang the tie beam from the roof peak — engineer the joinery, as connections govern timber truss design.
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