Why stairs and ramps are treated differently
On a level floor, a slip usually means a stumble. On a stair or ramp, it means a fall with height and momentum behind it, so the consequences are consistently worse. Australian building rules reflect that: while slip resistance for general floor areas is largely a matter of managing WHS risk against guidance, stairs and ramps in new building work carry explicit minimum classifications under the National Construction Code.
What the NCC requires for new work
For new construction and building work requiring approval, the NCC calls up minimum classifications from AS 4586:2013, the laboratory standard for new surface materials. The requirements distinguish between dry and wet conditions, with wet applying to surfaces that are external or otherwise subject to wetting:
- Stair treads and landings. P3 or R10 when dry, stepping up to P4 or R11 when wet.
- Nosings and landing edge strips. P3 when dry and P4 when wet. The nosing is the edge your foot actually loads as you descend, which is why it gets its own line.
- Ramps steeper than 1 in 20 but not steeper than 1 in 14. P3 or R10 dry, P4 or R11 wet.
- Ramps steeper than 1 in 14. P4 or R11 dry, P5 or R12 wet, the highest classifications the code asks for anywhere.
Always confirm the exact requirements with your certifier against the NCC edition applying to your project, but the pattern is stable: the steeper the surface and the wetter the conditions, the higher the classification. If the P and R codes are new to you, our guide to P ratings versus R ratings explains both systems.
What about existing stairs and ramps?
The NCC applies at the time of construction. Once the building is occupied, responsibility shifts to the ongoing WHS duty to keep the premises safe, and the benchmark becomes HB 198:2014, whose recommendations for stairs and ramps mirror the construction-time requirements. The practical difference is the test method: an installed stair cannot go to a laboratory, so it is tested in place with the wet pendulum to AS 4663:2013, giving a current P classification for each surface. Our guide to the wet pendulum and dry floor friction tests explains how the on-site methods work.
This matters because stairs lose slip resistance faster than almost any other surface. Every descending foot strikes the same strip of nosing, so wear concentrates precisely where grip is most needed.
The failure points we see most often
- Worn nosings. Anti-slip inserts and treads polish smooth or delaminate, leaving a hard, glossy edge at the most critical point of the stair.
- Painted or coated steel stairs. Common in industrial and back-of-house settings. Standard paint over checker plate or steel can be treacherous once dusty or damp.
- Sealed concrete ramps. A carpark or loading ramp that was acceptable as broomed concrete can fail after a sealer is applied for appearance or dustproofing.
- External ramps and stairs. Weathering, algae and moss steadily change external surfaces, and these areas must perform in the wet by definition.
- Feature stairs in polished materials. Stone, terrazzo and timber stairs chosen for looks are frequent shortfall candidates, especially near entries where wet shoes arrive.
If a stair or ramp falls short
Failures on stairs and ramps deserve the top of the rectification queue because the consequence of a fall is highest. The fixes are usually well defined: replacing or retrofitting nosings, applying anti-slip treatments or coatings suited to the substrate, or reworking the surface. Our guide on what to do when a floor fails a slip test covers the options, and every Slip Audit report ranks findings by risk so stairs that fail are flagged accordingly.
Test the stairs before they test you
If your building has stairs or ramps that have never been tested in service, they are the first place we would look. We test stairs, ramps and every other pedestrian surface across Melbourne, Sydney and Brisbane.