Slip resistance from R9 to R13, and where each belongs

Slip resistance is the property most often specified by habit. A number is copied from a previous project, the floor is laid, and either people slip or the floor cannot be cleaned. Both outcomes come from the same mistake: treating the R class as a rating of quality rather than as a description of a test under particular conditions.

What the R classification actually measures

The R classes come from DIN 51130, a ramp test. A test person walks upright, forwards and backwards, on an inclined sample wearing standard safety footwear, while the surface is wetted with a defined motor oil. The angle at which secure walking stops is recorded and averaged, and the result is placed in a class. R9 corresponds to the lowest measured angle range and R13 the highest, with R10, R11 and R12 between them.

Two implications follow. First, the test uses oil and shod feet, so it describes an industrial situation, not a wet changing room. For barefoot areas the relevant test is DIN 51097, which uses a soap solution and gives classes A, B and C. Second, the test measures an inclination, not a coefficient of friction, so R values do not convert directly into the pendulum test values used in parts of Europe and the United Kingdom. A specification that names both should name them separately.

Where standing liquid is expected, the displacement space classification V4, V6, V8 and V10 is used in addition. It describes the volume of liquid the profile of the surface can accept below the walking plane, in cubic centimetres per square decimetre. A profile that grips but holds no liquid can still be dangerous in a wash down bay.

Matching the class to the room

Higher is not better. Every step up in texture increases the effort of cleaning, and a floor that is not cleaned properly becomes slippery regardless of its class. The class should follow the contamination that the floor will actually carry.

• R9: dry internal areas with clean footwear, such as offices, retail sales areas, reception spaces and dry storage.
• R10: areas with occasional moisture or light soiling, such as staff corridors, canteens, washrooms and light assembly.
• R11: regular water or dust on the surface, such as goods handling, bakeries, laboratories, workshops and general production.
• R12: persistent grease, fat or water, such as commercial kitchens, dairies and beverage filling halls.
• R13: heavy continuous contamination with fats, blood or oils, typically meat and fish processing, usually combined with a displacement class.

Building it into the system

In a resin floor, slip resistance is produced by the aggregate and the finish, not by the resin. Broadcast quartz or aluminium oxide, sealed back with a wear layer, gives a durable and repeatable texture. Trowel texture in PU cement gives a coarser profile suited to the top classes. A rolled anti slip additive in a thin coating is the least durable option, because the additive wears through the film before the film itself is worn.

The property also degrades. Texture fills with fat and polishes under wheeled traffic. Periodic assessment is worth scheduling.

Points to settle before specifying

• The contaminant actually present, and whether footwear is worn.
• Whether shod (DIN 51130) or barefoot (DIN 51097) classification applies.
• Whether standing liquid requires a displacement class.
• The cleaning method and equipment available, and whether it can reach into the chosen texture.
• Transition zones between classes, where most slips occur.