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AS 4440 (truss installation): the chippy's standard on lift-and-set day

AS 4440:2004 is the install standard for nailplated timber roof trusses: temporary bracing, permanent bracing, bearing minimums, plumb/bow tolerance, lift-and-set.

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

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In plain English

AS 4440:2004, Installation of nailplated timber roof trusses, is the Australian Standard that sets the install-side rules for prefabricated nailplated trusses on residential and light-commercial buildings. The chippy is its primary user. The standard pairs with the truss manufacturer’s layout drawing and design certificate: the layout shows what goes where; the design certificate carries the loadings; AS 4440 sets how the trusses are actually erected, braced, and finished. NCC 2022 Volume Two H1D6 calls AS 4440 as the DTS pathway for truss install on Class 1 and Class 10 buildings (verified 2026-05-16).

The four things AS 4440 cares most about:

  1. Lifting and setting trusses without overstressing them during the install window when they have no lateral support.
  2. Temporary bracing to keep installed trusses plumb and aligned until permanent bracing is fitted.
  3. Permanent bracing to keep the finished roof structure stable under wind load.
  4. Bearing onto wall plates to deliver the design loads back into the supporting structure.

What it requires

For the chippy installing the trusses:

  1. Handle and store trusses on the flat or on edge to manufacturer’s spec. Side-loading a truss can crack nailplate teeth and invalidate the design.
  2. Lift trusses with a spreader bar above about 9 m chord length to keep deflection within limits. Single-point lifts on long trusses can break the bottom chord.
  3. Set each truss to the layout drawing position, plumb and square. Tolerance to AS 4440:
    • Plumb (out-of-plumb): maximum height/50 (e.g. 60 mm on a 3,000 mm-deep truss).
    • Bow (out-of-straight along the bottom chord): maximum length/200 (e.g. 45 mm on a 9 m truss).
  4. Fit temporary bracing as each truss is set, before the next truss is lifted. Temporary diagonal bracing from the first truss back to the wall plate (or floor) keeps the run stable.
  5. Install permanent bracing per the layout drawing’s bracing plan: longitudinal binders along the top and bottom chords, web bracing where called, and a continuous diagonal bracing system back to a braced wall.
  6. Achieve minimum bearing on wall plates per the truss design certificate (typically 35 to 50 mm). Insufficient bearing fails frame inspection.
  7. Fix tie-downs at every truss-to-plate junction per the manufacturer’s spec and the wind classification.

What it doesn’t cover

  • Design of trusses. Truss design is the manufacturer’s responsibility under AS 1720 series (timber structures). AS 4440 is the install side; AS 1720.5 covers nailplate-specific design.
  • Stick-framed roof construction. AS 1684 (residential timber-framed construction) covers stick framing. AS 4440 applies to prefabricated trusses only.
  • Steel trusses. Cold-formed steel trusses sit under AS/NZS 4600. AS 4440 is for timber nailplated trusses only.
  • Roof covering install. AS 2050 (concrete and clay tiling) and AS 1562 (sheet metal cladding) cover what goes on top of the truss frame.
  • Internal lining and ceiling install. Plasterboard ceiling install is AS/NZS 2589 territory.

Practical implications

  • Temporary bracing is the most-missed step. Trusses up but unbraced is a fall hazard for the chippy and a wind-collapse hazard for the partially-framed building. Bracing each truss as it goes up adds time but is non-negotiable under AS 4440.
  • Plumb tolerance failure is the most common frame-inspection defect. A truss set 80 mm out of plumb on a 3 m-deep stack of trusses is outside AS 4440 and is a fail. Recheck plumb after each gang of trusses is set; the truss next to a previously set truss often drifts when you fasten it.
  • Bearing tolerance gets caught at frame inspection. A truss bottom chord 25 mm shy of the wall plate is the kind of detail a certifier will measure. Cut the bottom chord at the wrong length (or set the wall plate position wrong) and you rebuild.
  • Cutting or notching a truss on site invalidates its design. Any field modification to a delivered truss needs engineer’s mark-up first. Drilling a 25 mm service hole through a top chord is the classic site-decision defect.
  • Wind classification drives tie-down density. Trusses in N3 wind region need fewer or simpler tie-downs than the same trusses in C2 cyclonic region. Read the wind classification (per AS 4055) and match the tie-down detail to it.

References

See also

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

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