Why slip resistance matters
Slips are one of the more common causes of injury on pedestrian surfaces, and one of the more preventable. A wet ramp, a polished tile entry, a timber deck in the rain — the surface itself is often the difference between a normal day and a fall. Anti-slip systems are the treatments and coatings that lift the grip of a surface to a measured, verifiable level, so it stays walkable when it gets wet. This is a plain-language guide to how those systems work, how slip resistance is measured, and what to weigh up when choosing one. No brands, no jargon for its own sake — just what you need to make a sound call.
Under the New Zealand Building Code, access routes have to be safe to walk on, and slip resistance is part of that. For building owners, body corporates and businesses, that translates into a duty of care: floors, stairs, ramps and outdoor paths need enough grip to be safe in the conditions they'll actually see, including when wet. The point isn't just compliance. A surface that meets a recognised slip rating is easier to defend if something goes wrong, and it removes a hazard that would otherwise sit there quietly until someone finds it the hard way.
The main types of anti-slip system
Anti-slip coatings
A liquid coating is applied over the surface and cured. Transparent coatings hold the look of the substrate underneath, which suits timber, tile and stone where appearance matters. The slip rating is set by the coating system and, in many cases, by a fine aggregate carried in it.
Aggregate or broadcast systems
A grit or particle is broadcast into a resin or coating to create a textured, higher-grip finish. These reach the upper slip ratings and suit ramps, loading areas and industrial floors where grip outranks finish
Etch and chemical treatments
Used mainly on tile and stone, these micro-profile the surface to raise wet grip without changing how it looks. They work on hard, dense surfaces rather than porous or timber ones.
Tapes, inserts and mechanical fixings
Adhesive strips, stair nosings and inlays add grip to specific spots (stair edges, single steps, thresholds) rather than a whole area. Useful as a targeted fix, less so as a system across a large surface.
How slip resistance is measured
The number that matters is the slip rating, and it comes from testing rather than a manufacturer's word for it. In New Zealand and Australia, new pedestrian surfaces are classified under AS/NZS 4586, which sets out the test methods and the resulting classifications. The most relevant of these for wet areas is the wet pendulum test. It measures how much a surface resists a sliding foot when wet, and returns a P rating from P0 (lowest grip) up to P5 (highest). You'll also see R ratings, a European scale from an oil-ramp test that's often quoted alongside the P rating. The two aren't directly interchangeable, but both describe the same thing: how hard it is to slip.
As a rough guide to how the P ratings map to real settings
- P3 suits interior areas not often exposed to water — lobbies, offices, living spaces, internal stairs.
- P4 suits wetter and outdoor settings — external walkways, entries, balconies, verandas, pool surrounds and covered outdoor areas.
- P5 suits the steepest and most demanding areas — sloping ramps, loading docks and commercial kitchens.
The right rating depends on the exposure of the specific area, not the building as a whole. A covered walkway and an open ramp on the same site can need different ratings.
Tiles, ceramics and stone
Tiles, ceramics and stone are both dense and stable surfaces. They take on coatings or etch treatments effectively.
Concrete
Concrete is porous and absorbent, so it usually needs a primer and a bit more product to seal and grip evenly.
Timber
Timber, including softwoods like pine, is absorbent and moves with moisture. It can be coated, but it takes more primer so the finished grip is worth confirming on the actual timber used.
Metal and glass
Metal and glass need a compatible system and thorough prep to bond, as there's nothing porous for a coating to key into.
Why on-site testing is worth it
Published figures are a starting point, not a guarantee. Real grip depends on the substrate, the prep, the application and the conditions on the day. For anything where the rating has to hold up — a public building, a school, a commercial site — the reliable move is to apply the system to a sample of the actual surface and run a wet pendulum test on it before committing to the full job. That gives a documented result tied to the real material, which is exactly what a specifier, council or building owner wants on file. It also removes the guesswork of assuming a lab figure will carry across to a different substrate.
Maintenance and longevity
An anti-slip finish is not set-and-forget. Grip can drop over time as dirt, grease and residue fill the surface texture, so regular cleaning with the right method keeps the rating where it should be. How long a system lasts depends on traffic, exposure and how well it's looked after. High-traffic and outdoor areas will want checking more often than a quiet interior floor.
Best approach
Best approach is to match the slip rating to the exposure of each area, match the system to the substrate, and confirm the result by testing before the full job goes ahead. For anything that has to meet a code or satisfy a specifier, testing on the real surface is what turns a claim into evidence. If you're not sure which rating an area needs, or whether a particular surface can be treated, it's worth getting advice before work is scoped. Getting the rating and the substrate right at the start is far cheaper than reworking a floor that doesn't grip once it's down.
