No. Our three slate types in natural surfaces are 100% non-slip (with the highest classification) and are therefore very suitable for external areas such as terraces, staircases and the like. We also supply slate in finished surfaces that are non-slip. All our slate surfaces have been tested and the slip resistance has been documented with an R number, which is a standard for testing slip resistance and is used for ceramic tiles, among other things. See our product datasheets for test results.