Non-slip decking

How is slip resistance measured?

With a pendulum, which gives a pendulum test value (PTV). HSE’s guidance, drawn from the UK Slip Resistance Group, sets the bands: 0 to 24 is high slip potential, 25 to 35 moderate, 36 and above low. The UKSRG’s publication on timber decking also gives 36 as the minimum for a surface to be classed as low slip potential. The wet reading matters outdoors.

What do manufacturers publish?

Few publish numbers on the product page.

• Millboard’s SATRA report for Modello Linear (EN 16165, Slider 57 for bare feet) gives dry values of 91, 92 and 71 and wet values of 51, 48 and 62 in three directions.
• Millboard’s Lasta-Grip is described as an Enhanced Grain look with a textured design for slip resistance without gritted strips, and its page gives no PTV numbers.
• The Enhanced Grain spec sheet lists two PTV values, 36 and 49, and we couldn’t confirm which is wet.

Ask any maker for the wet PTV, the test standard and the slider used. Results with different sliders and standards aren’t comparable.

Why is my decking slippery?

Usually dirt. Algae and wet leaves are the usual cause, which is why a UK DIYer who looked after his deck sweeps at least once a year. A UK gardener cleans in early spring, before the deck turns slippery, and warns that washing powder on wet boards makes them slippery while it works. New composite can be oily for 6 to 8 weeks because of a manufacturing release agent, according to Millboard. Guardian cautions about wet and icy conditions, and Eva-Last says grip is reduced when icy. See the cleaning guide for each maker’s method.

What about wooden decking?

Treated timber can be slippery when it’s green with algae. Grooved faces and anti-slip softwood grades exist, and one UK supplier gives its anti-slip pine, treated to UC3 and UC4, a 15 year service life. We haven’t sourced tests for anti-slip strips or coatings. An informal wet walk by a Canadian installer found composite and PVC grippy and planed raw timber slippery, which is anecdote, not a measurement.

How do I choose a grippy board?

Ask for the wet PTV, look for 36 or more, and choose a textured or grooved face for exposed or shady spots. Then keep it clean. The composite decking page lists the boards we have verified.