Non-Slip Tiles: Slip Resistance Classes R9–R13 Explained

Why Slip Resistance Matters for Tiles

Wet floors are one of the most common causes of falls in the home — especially in the bathroom, in the shower and on the patio. The slip resistance of a tile largely determines how safe a floor covering is in everyday use once water, soap or rain come into play. In Switzerland, specialist installers and planners rely on the well-established R-values (slip resistance according to the so-called inclined-plane method) as well as on the barefoot rating groups A, B and C. Both systems originally come from the German accident insurers' regulations, but have also become established here as a practical benchmark for builders, architects and tile layers.

Anyone planning a bathroom, installing a curbless shower or re-tiling a patio should not leave the slip resistance class to chance. The standard values are not bureaucratic window dressing, but a direct indication of how a tile behaves under realistic conditions — wet, with soap residue, barefoot or in shoes. Below we explain what classes R9 to R13 actually mean, where rating groups A to C apply, and which tile is suitable for which room.

There is no separate Swiss standard for slip resistance classes in the same form as in Germany; in practice, Swiss planners and tile manufacturers nevertheless rely on the established German test methods DIN 51130 (slip resistance R9–R13, tested with footwear and oil) and DIN 51097 (rating groups A, B and C for barefoot areas). These values are found in the technical data sheets of quality tiles and are a reliable point of reference for purchasing decisions.

Slip Resistance Classes R9 to R13 Explained Simply

The R classification measures the angle of inclination at which a test person still has secure footing on an inclined, oil-coated tile surface. The higher the class, the greater the measured frictional resistance and the more slip-resistant the surface. The scale ranges from R9 (low slip resistance) to R13 (very high slip resistance) and is generally applied to areas where footwear is worn.

For private living areas, R10 to R11 is sufficient in most cases. Anyone looking for a tile for the outdoor area should also pay attention to frost resistance: frost-resistant porcelain stoneware tiles with R11 or higher are the standard choice for Swiss patios, which must withstand rain, snow and freeze-thaw cycles.

Important to know: the R class is not a statement about the general quality of a tile, but exclusively about its slip behaviour under standardised test conditions. A high-quality tile can certainly be classified as R9 if it is designed for a dry living space. What matters is always that the class matches the intended location.

Barefoot Areas: Rating Groups A, B and C

For areas that are typically walked on barefoot — such as showers, pool surrounds or wellness areas — a second classification system applies: rating groups A, B and C. Here, testing is not done with oil but with water on a ramp walked by barefoot test persons.

• Group A: suitable for barefoot areas with lower loads, such as changing areas next to the swimming pool.
• Group B: higher requirement, typical for shower areas and pool surrounds with direct water contact.
• Group C: the highest level, intended for heavily wetted surfaces with a gradient, such as starting block areas or steep pool surrounds.

For a private shower floor tile, at least Group B combined with R10 or R11 is recommended — this way the tile is safe to walk on both barefoot and with wet feet. Shower wall surfaces have lower requirements, since they are not walked on directly; here, a solid shower wall tile with a robust, easy-to-clean surface is what counts most.

Which Tile for Which Room?

The right slip resistance class depends not only on the room, but also on how it is used: a family bathroom with children has different requirements than a rarely used guest toilet. The following overview shows practical guideline values for the most important rooms in and around the house.

Bathroom

In a classic bathroom with a separate shower or bathtub, R10 is usually sufficient for the floor area. Anyone who wants extra safety, or has children or older people in the household, should opt for R11. When choosing a bathroom tile, it's worth taking a look at the surface texture: slightly textured, matte surfaces generally offer more grip than high-gloss variants.

Curbless Shower

Curbless showers are level with the floor, barrier-free and on trend — but they place higher demands on slip resistance, since there is no shower tray edge. A shower floor tile of rating group B, combined with R10 or R11 and a properly executed gradient towards the drain, is recommended here.

Kitchen

In the kitchen, moisture, grease and the occasional dropped dish all come together. R10 is the standard minimum requirement here, with R11 to R12 in heavily used or commercial kitchens.

Outdoor Area and Patio

Outdoors, rain, leaves, frost and algae growth add further factors that can make a surface even more slippery. For patio tiles, the rule is therefore: frost-resistant porcelain stoneware, R11 upwards and, where possible, a textured surface. A smooth tile that is completely unproblematic indoors can turn into a slide on a wet patio.

Why Mosaic Tiles Score Twice in the Shower

Mosaic tiles are a classic choice for shower floors for good reason: their small format creates significantly more grout lines per square metre than large-format tiles. Each grout line acts like a small groove that provides extra grip and drains water more quickly. This makes mosaic tiles not only visually versatile, but also functionally sensible for wet areas.

Another advantage: mosaics can be laid precisely into a gradient, which is particularly important for curbless showers with a drain in the middle or at the side. Large-format tiles would need to be laboriously ground down for this, whereas mosaic tiles, thanks to their grout structure, can flexibly follow the slope. Combined with a slip-resistant surface texture (R10 or R11, group B), mosaic tiles are therefore one of the safest and, at the same time, most visually appealing solutions for the shower floor.

Caring for Slip-Resistant Tiles

Slip-resistant surfaces are usually somewhat more textured than smooth, high-gloss tiles — which also means that limescale, soap residue or dirt can settle more easily in the fine recesses. The laying pattern also plays a role: narrow grout lines between tiles additionally increase grip, which is why safety-relevant surfaces such as shower floors are often deliberately fitted with small-format tiles or mosaics. To preserve slip resistance over the years, the following applies:

• Clean regularly with a pH-neutral cleaner; avoid aggressive acids and abrasive cleaners.
• Remove limescale edges promptly, so that no smooth layer forms on the surface.
• For heavily textured surfaces, use a soft brush instead of a microfibre cloth to loosen dirt from the recesses.
• Outdoors, remove leaves, moss and algae regularly, as these further increase the risk of slipping.
• Avoid highly waxy or film-forming care products, as they can permanently impair slip resistance.

Anyone who follows these basic rules will barely lose slip resistance even after years of use — the tile stays as safe as on day one.

Frequently Asked Questions

What slip resistance class does a shower need?

For the shower floor, at least R10 is recommended, ideally R11, combined with rating group B for barefoot areas. This combination provides secure footing even with soap and running water.

Are mosaic tiles slip-resistant?

Thanks to their small format and high proportion of grout lines, mosaic tiles are generally grippier than large-format tiles. However, what ultimately determines actual slip resistance is the R class or rating group of the specific tile, not the format alone.

What does R10 mean for tiles?

R10 stands for normal slip resistance according to the inclined-plane test with oil. This class is suitable for bathrooms, kitchens and many entrance areas and is considered a solid standard for private wet rooms.

Which tiles are suitable for frost-resistant outdoor areas?

Frost-resistant porcelain stoneware with R11 or higher is the standard choice for Swiss patios and balconies, as it withstands both freeze-thaw cycles and wet weather. A textured surface additionally improves grip in rain and snow.

Can I also lay a tile with a high slip resistance class in a living area?

Yes, that's possible, although heavily textured surfaces with a very high slip resistance class (R12 or R13) often look more technical and are more laborious to clean. For living spaces without direct water contact, R9 or R10 is usually completely sufficient.

How can I tell a tile's slip resistance class?

Reputable manufacturers and specialist retailers state the R class, and where applicable the rating group, in the technical data sheet for each tile. It's worth taking a close look at this information when buying, especially for bathrooms, showers and outdoor areas, where slip resistance is safety-relevant.