Understanding slip ratings: specifying porcelain for Australian wet areas and outdoor spaces

Slip resistance is one of the first things a specification has to settle, and one of the easiest to get wrong when the data isn’t in front of you. Wet areas, pool surrounds, entries and commercial floors have to perform underfoot, however good they look in photos. This guide is for the architects, designers and builders who specify our surfaces. It covers what the two common slip ratings measure, where each one matters, and how to read them on a NIDO data sheet before you commit to a single square metre.

Two ratings, two tests

Australian projects usually describe slip resistance in one of two ways, and the two measure different things.

The P classification comes from a pendulum test. A swinging rubber slider measures how much grip a wet surface gives, and the result is graded from P0 to P5. It’s the classification most often cited against Australian standards for pedestrian surfaces, and the one many building surveyors and access consultants will ask for. A higher number means more wet grip, so a level entry or a poolside may call for a higher class than a covered internal floor.

The R classification comes from a ramp test that started in German DIN practice. A person walks an oiled ramp while its angle rises, and the angle at which they lose footing sets the grade, from R9 to R13. On our data sheets it appears as “Oil Ramp”. Manufacturers quote it widely because it compares finishes cleanly: an R10 grips better than an R9, and R11 or higher is usual where water meets bare feet or heavy traffic.

The two scales don’t convert. An R11 finish isn’t automatically any particular P class, because the tests are different. If your compliance path is written against the pendulum classification, ask for pendulum data. If a comparative description of the finish is enough, the R rating will do.

Where slip rating matters

• Bathrooms and ensuites. These floors get wet every day, and a textured face usually grips better than a high polish.
• Pool surrounds and outdoor entertaining. Bare feet and standing water make this the hardest case. Start with a finish rated for outdoor use, then check its wet rating against what your certifier needs.
• Entries and thresholds. The step from a wet path onto a dry floor is a classic slip point, so specify for the wet condition.
• Commercial floors. More foot traffic and heavier cleaning raise the bar. Your access consultant or surveyor will usually set the target classification.

A polished face and a natural face can sit in the same range and behave very differently underfoot. That’s useful. You can hold one design language through a project and still choose the finish room by room, to suit how each floor is used.

How to read it on a NIDO surface

Every NIDO product page lists the surface’s technical data, and every product has a data sheet you can download without logging in. Some product pages don’t show a slip rating yet. Before you put a surface on a floor that will get wet, check the rating on its current data sheet against what your project requires. If there’s no rating, or the page and the sheet don’t match, ask us for the test data rather than inferring a rating from the finish or the collection.

Alongside slip rating, these are the details that decide whether a surface suits the job:

• Water absorption. Our porcelain is listed at below 0.5% (E < 0.5%). Low absorption matters outdoors and anywhere staining is a risk.
• Finish. Polished, lappato, natural or structured. The finish sets both the look and the grip.
• Format and edge. Our current ranges are rectified, for tight joints and large-format layouts.
• Indoor or outdoor use. Each product page states it, so you aren’t left to guess.

A NIDO trade account opens the Download Hub, where BIM and CAD files sit in one place, ready to drop into your model.

Specify with confidence

Slip rating is where a good-looking surface shows whether it belongs in the space. Read it against the real condition (wet, barefoot, heavily trafficked, or all three), match the finish to the use, and confirm the classification your compliance path needs. If the number you need isn’t on the sheet, ask us. We would rather answer the question than have you guess.

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This guide is general information for specification professionals. Confirm the slip classification your project needs against the current standards and your certifier’s advice, and check the product’s current data sheet before you specify.