Slip ratings are an important way of assessing how safe a surface will be underfoot - especially in outdoor areas where rain, frost, or organic matter can make surfaces slippery. The most common system used in the UK and Europe is the R-rating, based on the DIN 51130 test. In this test, a person walks on an inclined ramp coated with oil while wearing safety footwear. The angle at which they begin to slip determines the tile’s rating.
The scale runs from R9 to R13:
• R9 – low slip resistance, for dry indoor areas only
• R10 – suitable for light domestic use and bathrooms
• R11 – good slip resistance for most outdoor patios and paths
• R12 – high slip resistance, suitable for driveways, pool surrounds, or steep areas
• R13 – maximum resistance, typically for industrial or commercial zones
For comparison, the Pendulum Test Value (PTV) used in the UK correlates roughly as follows: R11≈ PTV 36–55 (moderate to low risk) and R12 ≈ PTV 55+ (very low risk). It’s worth remembering that no surface is completely slip-proof. Even an R12 tile can become slippery if it’s covered with something like wet leaves, moss, or a banana skin. Slip ratings are measured on clean surfaces — contaminants reduce performance dramatically.
Water also plays a key role. As surfaces become wetter, the microscopic film of water can act as a lubricant, especially on smoother tiles. That’s why outdoor porcelain and stone tiles often have raised textures or structured finishes to break surface tension and provide extra grip. In recent years, high-end porcelain manufacturers have developed advanced anti-slip micro-textures that feel smooth to the touch yet maintain or even improve slip resistance.
These surfaces are created using laser-etched or digitally pressed textures that interact with water to create friction at a microscopic level. The result is a tile that is comfortable underfoot but exceptionally safe when wet, ideal for areas that connect indoor and outdoor spaces.
Choosing the right slip rating for your space — and keeping it clean — ensures the surface remains both safe and attractive year-round
