Most AS 1657 stair problems are not detailing problems. They are decisions made in the wrong order: a stair is fitted into whatever space is left between a floor and a platform, the treads are detailed, and only then does someone check which part of the standard the geometry actually falls under. This guide sets out how an industrial stairway is resolved under AS 1657 (Fixed platforms, walkways, stairways and ladders) — the order of decisions, what each one controls, and what has to be on the drawings before the steel goes to the workshop.

It is written for engineers, fabricators and project managers responsible for plant access. It deliberately points you at the clause to read rather than quoting dimensional limits: the governing values depend on the stair’s pitch and use, and the only safe source for them is the current edition of the standard itself. For the wider picture of platforms, walkways and ladders, start with our AS 1657 overview.

Is it an AS 1657 stair or an NCC stair?

This is the first question and it is the one most often skipped. AS 1657 covers fixed access that people use to reach, operate and maintain plant, equipment and structures: mezzanine and conveyor access, machinery platforms, tank and silo stairs, pipe-rack crossovers and roof access. Stairs that form part of a building’s general circulation or its exit path are governed by the National Construction Code, which carries its own stair geometry, balustrade and slip-resistance requirements.

The two sets of rules are not interchangeable, and a stair can sit in a grey zone — a stair inside a building that leads only to a plant room, for example. The NCC itself allows AS 1657 for certain non-public access situations, but whether a particular stair qualifies is a call for the building certifier, made against the current National Construction Code. Settle it in writing before detailing. A stair drawn to AS 1657 that the certifier treats as an exit stair is a redesign, not a mark-up.

Pitch decides which rules apply

AS 1657 sorts access by angle. A stairway, a step-type ladder and a rung-type ladder each occupy their own band of pitch, and each band brings a different set of requirements for treads, risers, handrails and landings. A designer who draws a “stair” that is actually steep enough to be a step-type ladder has not drawn a non-compliant stair — they have drawn a step-type ladder, and every tread and rail on it has to be checked against that part of the standard instead.

So the pitch is fixed first, from three inputs: the vertical rise between the two levels, the horizontal run available on plan, and the use the stair will see. Frequent use, use while carrying tools or parts, and use by people who are not regular operators all push toward a shallower pitch. Only once the pitch is confirmed inside the stairway band, with margin, is it worth detailing anything. Stairs drawn right on the boundary of a band are the ones that change category the moment a floor level moves on site.

Going and riser: consistency matters as much as the numbers

Within the stairway band, AS 1657 sets limits on the riser height and the going (tread depth), and a relationship between the two that keeps the stride comfortable. Read those values from the standard for your pitch. What the drawings must then achieve is consistency: every riser in a flight the same, every going the same, measured nosing to nosing.

Inconsistency is the defect that gets past review most often, because it is rarely drawn — it is built. It appears where the first or last riser absorbs a floor-level discrepancy, where a grating tread sits at a different level from a checker-plate landing, or where a concrete plinth is poured higher than the setout. Three habits prevent it:

Dimension the rise from confirmed levels, not from nominal ones. Where the finished floor is not built yet, the drawing should say which level the stair is set out from and how a variation will be taken up.
Show the tread type at every step, including the top and bottom. A change of tread product changes the effective riser.
Detail the landing interface. The top riser ends where the landing surface is, not where the landing steel is.

Landings, flights and headroom

Long flights need intermediate landings, and AS 1657 limits how many risers a single flight may have before one is required. Landings also have minimum dimensions so that a person can stop, turn and stand clear of the stair. These are layout decisions, which is why they belong in the general arrangement rather than in the detailing: a landing that does not fit is a re-route, not a detail change.

Headroom is the other layout item. It is measured vertically above the pitch line and above every landing, and it is the requirement most often lost to services: cable trays, pipe runs and structural members routed after the stair was positioned. In our experience reviewing access designs, a headroom failure discovered at model review is one of the more expensive corrections to make, because it usually means moving the stair or the service, not adjusting the steel. We cover this pattern, and six other recurring failures, in AS 1657 platform design: 7 common mistakes.

Handrails and guardrails on the stair

AS 1657 distinguishes a handrail, which is there to be gripped while moving, from a guardrail, which is there to stop a fall from an open edge. A stairway usually needs both functions, and the standard sets when handrails are required on one or both sides, their height measured above the nosing line, the clearance needed for a hand to grip them, and how they must terminate at the top and bottom of the flight.

On drawings, the details that most often go missing are the ones at the transitions:

Where the stair handrail meets the landing guardrail. The rail height changes basis — from above the nosing line on the flight to above the walking surface on the landing — and the junction needs its own detail.
Rail ends. Ends that stop short or project into the walkway are a snag hazard; show how each end returns or terminates.
Openings below the top rail. Mid-rails or infill must keep the openings within the standard’s limit along the raked flight, not only on the flat.
Post spacing and fixing. The rail system must carry the design loads in the standard; post spacing and base fixings are where that capacity is decided.

Treads, nosings and slip resistance

Industrial stairs are usually built with grating treads, checker-plate treads or folded plate, each with a defined nosing. AS 1657 requires slip-resistant treads and a nosing that is visible and does not catch a foot. In practice this means specifying the tread product by name and type on the drawing, showing the nosing profile, and noting the environment — wet, oily, outdoor or washdown — because that drives which tread is suitable. “Tread to suit” on a fabrication drawing is not a specification.

Loads and the structural check

AS 1657 sets the design loads that stairways, landings and rails must carry; the members and connections are then designed to the relevant structural standard, normally AS 4100 for steel. The stringer size, tread fixing, landing framing and base and head connections all come out of that design. The drafting job is to carry every one of those decisions onto the drawings without loss: section sizes, plate grades, bolt sizes and categories, weld types and the connection to the supporting structure. If the head connection lands on a platform beam, the beam’s capacity to take it is part of the check, not an assumption.

What the drawing set should carry

A stair package that a workshop can build without phoning anyone, and that a reviewer can check against AS 1657, normally includes:

General arrangement — plan and elevation, the two levels the stair connects, the pitch, and the clear width and headroom envelope.
Setout — the datum levels, riser count and going, with how a level variation will be absorbed.
Stringer and tread details — section sizes, tread product, nosing, and tread fixing.
Landing details — framing, flooring, and the interface with the first and last riser.
Handrail and guardrail details — heights, post spacing, mid-rail or infill, and every transition and termination.
Connection details — base and head connections, with bolts, welds and plate grades specified.
Notes — the standards the design is to, the design loads, protective coating, and any clause the reviewer should be referred to.

Most of this sits within the conventions for fabrication documentation generally; our fabrication drawing work follows the same structure, and the construction detail drawings guide covers how callouts should link each detail back to the GA.

A practical review order

When a stair design comes to us for drafting or review, we check it in the same order the decisions cascade, because a failure early in the list invalidates the work after it:

Governing standard confirmed — AS 1657 or the NCC — and recorded.
Pitch inside the stairway band, with margin for level variation.
Riser and going within the limits for that pitch, and consistent through every flight.
Flight lengths, landings and headroom resolved in the layout.
Handrails and guardrails, including every transition and end.
Treads, nosings and slip resistance specified, not left to the fabricator.
Structural design carried through to members and connections.

Each item is recorded as compliant, non-compliant or needing information, and the non-compliant items are sorted by what they cost to fix. Rail and tread changes are cheap; anything that moves the stair is not.

Where to read the requirements

The governing values — pitch bands, riser and going limits, landing sizes, headroom, rail heights and design loads — are in the current edition of AS 1657, available from Standards Australia. Fall prevention more broadly is covered by Safe Work Australia’s model code of practice on managing the risk of falls at workplaces, which your state regulator adopts. Read both against your specific stair; values carried in memory from the last project are the most common source of non-compliance we see.

ASTCAD details AS 1657 stairways, platforms and ladders as part of our structural steel detailing service, from the engineer’s design through to fabrication-ready drawings. If you have a stair or access package to document or review, send us the drawings and we will scope it.

AS 1657 Stairways: How to Design a Compliant Industrial Stair