Wooden decking boards, WPC and plastic can become slippery outdoors due to fungal and algae infestation. The slip resistance of floor coverings is measured according to the DIN 51130 standard and classified into slip resistance classes.
The scale ranges from R9 to R13. A terrace with the anti-slip class R9 is non-slip up to an angle of inclination of 6°-10°. Decking boards in anti-slip class R13 are non-slip up to an angle of inclination of 35°. Decking boards with a slip resistance class of R11 to 13 should be used for commercial and public areas. The test procedure for the anti-slip classes is not yet very widespread.
Therefore, no reliable test results can be found for most woods. Basically, however, decking boards made of tropical wood are less slippery than decking boards made of larch or spruce, as these are much more susceptible to fungi and rot. In addition, smooth decking boards are less slippery than corrugated ones, since the corrugated wood dries less well and is therefore also more susceptible to fungi and algae.