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Roof framing: conventional (stick-framed) construction

How to frame a conventional timber roof in Australia: AS 1684.2 design, rafter sizing, ridge board vs ridge beam, hip and valley framing, when to choose over trusses.

By Dan Waring. Last updated 10 May 2026. Verified 10 May 2026.

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TL;DR

Conventional (cut-and-pitch) roof framing is built entirely on-site from individual members sized off AS 1684.2:2021 span tables. It is the default for complex roofs, cathedral ceilings, remote sites where truss delivery is impractical, and heritage or renovation work where geometry doesn’t suit prefabrication. Labour cost is higher than trusses: a typical 200 m2 footprint runs $12,000 to $20,000 for chippy labour plus materials in 2026, versus $9,000 to $15,000 supply-and-set for trusses. The most common defect is undersized rafters from using a wrong span table input (wind class, load width, or stress grade). Trusses beat stick framing on a standard rectangle; stick framing wins on anything complex, steep, exposed to height limits on truss delivery, or requiring usable ceiling volume.

When you do this

After wall frames are completed, inspected, and all tie-down connections are confirmed. Sequence: ceiling joists set, ridge board or ridge beam erected, common rafters pitched, hip and valley members cut and fixed, underpurlins and struts installed (if required), permanent bracing, sarking, battens, roofing. The roof is on the critical path.

Who’s involved

RoleResponsibility
ChippySetting out, cutting all members, erecting frame
BuilderConfirm member sizes from correct span table before framing starts
Structural engineerRequired when AS 1684 scope is exceeded or engineer’s details apply
RooferBattens and roofing after frame is complete and sarked
Inspector / private certifierFrame inspection before roofing closes the frame

When to choose conventional over trusses

Stick framing is the better choice in these situations:

  • Complex roof geometry: multiple hips, valleys, irregular plans, and intersecting ridges are difficult to engineer as prefab trusses and simple to execute in conventional framing.
  • Cathedral or vaulted ceilings: rafters create ceiling volume; trusses (including scissor trusses) require engineering and increase cost for the same effect.
  • Site access constraints: raw sawn timber can reach a site by ute, boat, or helicopter. Truss packs require a hiab or crane and clearance for long bundles.
  • Renovation and heritage work: matching an existing pitch, splicing into an old frame, or dealing with non-standard geometry is easier member-by-member.
  • Low-volume or bespoke builds: the lead time for a truss set (3 to 6 weeks from order to site) is removed when framing from stick.
  • Hybrid framing: trusses for the main rectangle, conventional for the porch, alfresco, garage skillion, or dormer where geometry breaks the truss layout.

Source: WoodSolutions, AS 1684 User Guides, Standards Australia (verified 2026-05-10); AS 1684.2:2021, Standards Australia (verified 2026-05-10).

The standard and its limits

AS 1684.2:2021 is the deemed-to-satisfy (DTS) path under NCC 2022 H1D6(4) for conventional timber-framed roofs in non-cyclonic areas. Cyclonic areas use AS 1684.3:2021. Scope limitations apply: maximum two storeys of timber framing, maximum building width 16,000 mm (excluding eaves), maximum external wall height 3,000 mm. Outside these limits AS 1684 loses its DTS status and a structural engineer’s design is required.

Source: NCC 2022 H1D6, ABCB (verified 2026-05-10); AS 1684.2:2021, Standards Australia (verified 2026-05-10).

Roof types and terminology

Coupled roof: roof slope not less than 10 degrees; rafters are tied together in opposing pairs by ceiling joists fixed at the pitching points (wall plate). The ceiling joist prevents the rafters from spreading. This is the most common form in residential construction. Collar ties may supplement ceiling joists at mid-span for steep pitches.

Non-coupled roof (including cathedral/skillion): no ceiling joists tying opposing rafters. The ridge or intermediate beam carries the load; the beam is supported by walls or posts at each end. Member sizes and beam design are from the span tables or engineer’s details.

Key members:

MemberRole
Common rafterThe primary pitched member; spans from wall plate to ridge; sized from span tables
Ridge boardNon-structural apex board; rafters bear against it but it does not carry load; minimum 19 mm thick, depth not less than rafter depth
Ridge beamStructural beam carrying rafter loads to posts or walls; required for non-coupled roofs; engineer-designed when outside span tables
Ceiling joistHorizontal tie between opposing rafters; prevents rafter spread in a coupled roof; sized from span tables
Collar tieSecondary horizontal brace between rafters above the ceiling joist line; not a substitute for ceiling joists
UnderpurlinHorizontal member below rafters at mid-span, supporting long rafters that exceed the direct rafter span; runs parallel to eaves
StrutInclined or vertical compression member transferring underpurlin load down to an internal wall or strutting beam
Hip rafterDiagonal rafter at the corner of a hip roof; runs from ridge end to corner of wall plates; carries jack rafter loads
Valley rafterDiagonal rafter at the junction of two roof planes; runs from ridge to re-entrant corner
Jack rafterShort rafter running from wall plate to hip rafter (hip jack) or from valley rafter to ridge (valley jack)
BirdsmouthNotch cut into the rafter where it bears on the wall plate; creates a level seat; depth limited by AS 1684 to preserve structural section

Source: AS 1684.2:2021, Standards Australia (verified 2026-05-10).

Steps

1. Determine wind classification and select span tables before cutting

The site wind classification (AS 4055:2021 Amd 1:2024, wind regions N1 to N4 or C1 to C4) drives every span table input. A job framed to N2 tables on a site classified N3 is a structural non-compliance that doesn’t show until a storm event. Confirm the classification from the structural engineer’s drawings, the building permit, or a wind classification report before ordering or cutting timber.

AS 1684.2 span tables are published as separate supplements keyed to wind class and timber stress grade (F-grades and MGP grades). Select the correct supplement booklet for the job.

Source: AS 4055:2021 Amd 1:2024, Standards Australia (verified 2026-05-10); AS 1684.2:2021, Standards Australia (verified 2026-05-10).

2. Set out the roof and confirm member sizes from span tables

Mark wall plate positions, confirm eaves overhangs, measure rafter spans (measured along the rafter, not the horizontal projection), confirm load widths (the plan area of roof each member carries), and read off minimum member sizes from the appropriate AS 1684 span table for:

  • Common rafters (spacing, span, load width, wind class, stress grade)
  • Ceiling joists (spacing, span, load width)
  • Underpurlins (if rafter span exceeds direct-rafter table limits)
  • Ridge board dimensions
  • Hip and valley rafter sizes (span tables include specific sections for hip and valley members; hip and valley rafters are deeper than the common rafter due to the compound angle and additional load)

If any member exceeds the limits in the span table, an engineer’s design is required before proceeding.

Source: AS 1684.2:2021, Standards Australia (verified 2026-05-10).

3. SWMS and fall protection before work at height

Conventional roof framing involves sustained work at height. Falls greater than 2 m constitute HRCW under the model WHS Regulations. A site-specific SWMS covering fall protection, safe access to the plate line, and working platform design is required before roof framing starts.

For a single-storey build where the fall is less than 3 m, a risk assessment determines the controls; for two-storey or high-set, edge protection or catch platforms are typically required. WorkSafe WA guidance: working platforms on ceiling joists are an accepted control for in-frame work on conventional roofs.

Source: WorkSafe WA, Domestic construction controlling falling risks on roof structures (verified 2026-05-10).

4. Fix ceiling joists

Set and nail ceiling joists before pitching rafters in a coupled roof. Ceiling joists are fixed to the top plate on both sides and to the rafters at the pitching point when the rafters go up. Spacing typically matches rafter spacing. Ceiling joists that are undersized or fixed incorrectly to the rafter are a leading cause of rafter spread detected at frame inspection.

5. Erect ridge board or ridge beam

For a gable roof: erect the ridge board at the correct height (calculated from pitch and run), supported temporarily at each gable end. For a hip roof: set the ridge board between the two hip-end pairs; the ridge end height governs the hip geometry. For a non-coupled roof: fix the structural ridge beam to its bearing supports (posts or walls) before any rafter is pitched; the beam carries the roof load, so it must be complete and bearing before rafters go on.

Ridge board minimum depth: not less than the rafter depth. Ridge board minimum thickness: 19 mm for typical residential spans; 35 mm (or the rafter stress grade, whichever is greater) where strut spacing to the ridge exceeds 1,800 mm.

Source: AS 1684.2:2021, Standards Australia (verified 2026-05-10).

6. Cut and fix common rafters

Mark, cut, and fix rafters in opposing pairs where possible to keep the ridge in position and the load balanced. Key cutting points:

  • Plumb cut (ridge cut): cut at the pitch angle at the top; the rafter bears against the ridge board.
  • Birdsmouth: notch at the wall plate bearing. AS 1684 limits birdsmouth depth to preserve the net rafter section. Do not cut deeper than the standard allows.
  • Eaves/tail cut: tail cut at the required overhang; fascia or eave profile applied after.

Fix rafters to wall plates per AS 1684 tie-down requirements for the wind class. In N3, N4, and all cyclonic regions, framing anchors or hurricane straps are required at every rafter-to-plate connection; skew nails alone are not sufficient.

Source: AS 1684.2:2021, Standards Australia (verified 2026-05-10).

7. Cut and fix hip and valley rafters

Hip and valley rafters run diagonally and carry compound loads. They are sized from the AS 1684 hip and valley rafter span tables, which are separate from the common rafter tables. Hip and valley members are typically deeper than the corresponding common rafter.

For a hip roof:

  • Set the two end common rafters and the crown end rafter to establish the ridge height.
  • Fix the hip rafter from ridge end to corner of wall plates; check plumb.
  • Cut and fix jack rafters between hip rafter and wall plate; jack rafter lengths are calculated from the hip geometry.

For a valley:

  • Fix the valley rafter from the ridge junction down to the re-entrant wall plate corner.
  • Fix valley jack rafters (from valley rafter up to the ridge on each side).
  • Valley flashing and sarking must turn up under the valley rafter; design the valley to shed water to eaves or gutters.

Source: AS 1684.2:2021, Standards Australia (verified 2026-05-10).

8. Install underpurlins and struts (if required)

Where rafter spans exceed the direct-rafter span tables, an underpurlin provides an intermediate support point at mid-span, reducing the effective rafter span. The underpurlin runs parallel to the eaves, typically bearing in the rafter’s underside. Struts transfer underpurlin loads down to internal load-bearing walls or a strutting beam.

Strut angle: AS 1684 specifies limits on strut angle from vertical. A strut bearing on a non-load-bearing wall is a defect: confirm wall status from the structural drawings before fixing struts. Strutting beams span between load-bearing walls where there is no convenient internal wall directly under the strut point.

Source: AS 1684.2:2021, Standards Australia (verified 2026-05-10).

9. Install collar ties

Collar ties are horizontal members fixed between opposing rafters, above the ceiling joist line, to provide additional lateral stability at mid-rafter height on steep pitches. They are not a substitute for ceiling joists. Per AS 1684, collar ties are typically required where the roof pitch exceeds 35 degrees.

Source: AS 1684.2:2021, Standards Australia (verified 2026-05-10).

10. Install tie-down connections at all rafter-to-plate bearings

Every rafter-to-plate connection needs the hold-down type specified for the site wind classification:

Connection typeTypical application
Skew nails (2 x 3.05 mm dia minimum per AS 1684)N1-N2
Framing anchor (MiTek, Pryda or equivalent)N2-N3
Hurricane strap (over top chord, both sides of plate)N3-N4 and all cyclonic
Engineered hold-down (bolt-through)Cyclonic C1-C4

Do not mix connection types without engineering advice. In N3, N4, and cyclonic zones, every rafter needs the specified connector. One missing connector is the weak point in a wind event.

Source: AS 1684.2:2021, Standards Australia (verified 2026-05-10); NCC 2022 H1D6, ABCB (verified 2026-05-10).

11. Fix permanent bracing, sarking, and battens

Roof bracing in conventional construction is typically achieved by: diagonal steel rod or strap bracing fixed to the top chord of the rafters, combined with the batten layer as the completed permanent restraint. Fix sarking (reflective foil, breather membrane, or sarking board per the design) immediately after framing is complete. Battens are fixed per the AS 1684 tie-down schedule and batten supplier’s span tables.

Do not remove any temporary propping until battens are fixed and the frame is permanently stable.

Tolerances and acceptance

ElementStandardRequirement
Rafter plumb (finished)HIA GuidePer current HIA Guide to Materials and Workmanship and relevant state Guide. Verified numerical value pending HIA member access. [HIA-088]
Rafter bow (finished)HIA GuidePer current HIA Guide to Materials and Workmanship and relevant state Guide. Verified numerical value pending HIA member access. [HIA-089]
Ridge board level (straightness)HIA GuidePer current HIA Guide to Materials and Workmanship and relevant state Guide. Verified numerical value pending HIA member access. [HIA-090]
Rafter spacing (deviation from specified)HIA GuidePer current HIA Guide to Materials and Workmanship and relevant state Guide. Verified numerical value pending HIA member access. [HIA-091]
Rafter-to-plate bearingAS 1684.2Minimum bearing per span table and Figure requirements; birdsmouth depth within AS 1684 limits
Tie-down connectorsAS 1684.2 / structural drawingsPer AS 1684 tie-down schedule for wind classification; no substitution without engineer approval

Documents needed

  • Structural engineer’s framing plan and tie-down schedule (or AS 1684 span table set for the wind class)
  • Wind classification report or certificate (AS 4055:2021 Amd 1:2024)
  • SWMS for roof framing work (HRCW where falls exceed 2 m)
  • AS 1684.2:2021 span table supplements for the relevant wind class and stress grade

Common holds

  • Wrong span table used. Verify wind classification and stress grade against the permit and engineer’s drawings before reading any table. A 2006 edition span table used on a 2026 job is a compliance risk.
  • Underpurlin bearing on non-load-bearing wall. Struts must bear on load-bearing walls or a strutting beam. Confirm wall status from structural drawings.
  • Birdsmouth cut too deep. Cutting beyond the AS 1684 limit reduces net rafter section and can split the rafter at the plate under load.
  • Hip rafter sized as a common rafter. Hip and valley members use their own span table section; using common rafter sizes for hip rafters is undersizing.
  • Rafter tie-down skipped or wrong type. Skew nails alone are not adequate in N3, N4, or cyclonic areas. Nail connections missing at any rafter-to-plate bearing are a hold point at frame inspection.
  • Rafter spread from disconnected ceiling joists. In a coupled roof, if ceiling joists are undersized or not properly fixed to both rafter and plate, the roof can spread under load, pushing walls out.
  • Ridge board not supported before rafters pitched. An unsupported ridge will sag under the weight of the first few rafters. Temporary propping is required.

References

See also

Last updated: 2026-05-10. Verified: 2026-05-10. Quarterly review for currency.

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