With dense buildings and a humid rainy season, floor slip resistance is the specification most often overlooked in Hong Kong, and the one with the highest cost when it goes wrong. Stone slip resistance is generally measured three ways: the German DIN 51130 R rating (R9 to R13), the European EN 14231 pendulum test value (PTV) and the American ASTM C1028 static coefficient of friction.
DIN 51130 tests slip on an inclined ramp and grades from R9 to R13; the higher the number, the better the grip. R9 is normally enough for dry interiors; R10 to R11 for wet areas, entrance lobbies and kitchens; R11 to R12 or above for outdoor slopes, pool surrounds and public stairs.
EN 14231 swings a pendulum to simulate a shoe sole on the surface; higher readings mean better grip. A PTV above 36 is generally treated as low risk, below 36 as moderate to high risk. Many Hong Kong public works and estate deeds specify this metric.
Polished has the highest gloss but is the most slippery when wet. Honed is softer looking with moderate grip. Flamed and bush-hammered are rough and give the best grip, standard outdoors and on steps. Sand-blasted and antique finishes sit in between. Balance grip against cleaning difficulty.
Rougher means safer but traps dirt and is harder to clean. Use polished or honed in dry interiors; honed or fine-sand in semi-outdoor areas, bathrooms and kitchens; flamed or bush-hammered outdoors, on steps and slopes, with periodic pressure washing.
Specify R11 or above for wet areas, with honed, fine-sand or bush-hammered finishes, plus proper falls to drainage and well-placed floor drains to avoid standing water.
It is usually acceptable when dry, but grip drops markedly when wet. It works in living rooms; for bathrooms, kitchens and entrances use honed or textured finishes, or add anti-slip strips.
Yes. Flamed and bush-hammered finishes make the surface matt and rough and slightly lighten the colour. Check the effect on a sample first - we can supply physical samples in different finishes.