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Truss layout drawing

The plan drawing from the truss manufacturer showing each truss position, type, spacing, and bearing. The chippy's reference for installation under AS 4440.

By Dan Waring. Last updated 16 May 2026. Verified 16 May 2026.

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A truss layout drawing is the plan-view drawing supplied by the prefabricated roof truss manufacturer that shows, in order:

  1. Each truss type and identifier (T1, T2, GE1, etc.), keyed to the truss design certificate.
  2. The position of each truss on the wall plate, dimensioned from a fixed reference (commonly the front and side wall plates).
  3. The spacing between trusses (typically 600 mm or 900 mm centres on residential).
  4. The bearing points on the wall plates, with the load each bearing transfers down.
  5. Girder trusses, hip ends, jacks and valley framings, with their relationships to the main truss runs.
  6. Bracing requirements (longitudinal binder, diagonal web bracing) called up from the truss designer’s specification.

The layout drawing is the chippy’s primary reference on lift-and-set day. It is read alongside the truss design certificate (one per unique truss type, listing engineering calculations) and the bracing specification.

Where it sits in the build sequence:

  • At order: builder checks the layout against the architectural plans and the structural drawings; bearing points must line up with engineered wall plates and load paths.
  • At delivery: each delivered truss is matched to the layout by tag; missing or wrong-marked trusses are quarantined before they are mistakenly fitted.
  • At install: chippy works through the layout truss-by-truss, holding each truss square and plumb until the next-spaced truss and the bracing are set.
  • At frame inspection: the certifier reads the layout against the constructed frame to verify each truss is in position, every bracing element is fitted, and tie-downs match the manufacturer’s spec.

Under AS 4440:2004 (Installation of nailplated timber roof trusses), the layout drawing is the install document the standard cross-references throughout. Without it, the AS 4440 install rules cannot be followed because the rules are written in terms of “as shown on the layout drawing”.

Common defects from a missed or misread layout drawing:

  • Trusses installed at incorrect spacing: load path overstressed, frame inspection fail.
  • Girder truss in the wrong position: structural span exceeded, certifier rejects.
  • Bracing omitted or in the wrong position: roof racks under wind load.
  • Hip-end set with site-built infill instead of the supplied jacks: load path inconsistent with the design.

Also known as: truss plan; truss layout; truss schedule (loose); roof truss drawing.

Category: Structure.

See also

Last updated: 2026-05-16. Verified: 2026-05-16. Quarterly review for currency.

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