The UK’s independent authority on slip resistance

Timber decking: How to prevent slip accidents

Just a few simple measures will ensure your timber deck remains safe for everyone to use all year round. Preventing slip accidents starts at the planning stage by following good design and material selection principles.

Guidance is at hand from the Timber Decking and Cladding Association (TDCA) – an independent, not-for-profit advisory organisation, established to influence and promote good industry practice.

The TDCA recommends that a deck should be:

  1. A free draining and well-ventilated structure
    The organisms responsible for slipperiness – moulds, algae and mosses – like damp conditions. Ensure your deck sheds water and dries out quickly to keep them at bay.
  2. Constructed using fit for purpose products that are correctly specified
    Choose timber types suitable for use outdoors and capable of giving at least 15 years’ service life. This applies to both the deck surface and supporting substructure.

Once the deck is built, keep it clean to prevent the build-up of dirt and debris. This too can harbour and encourage the growth of organisms responsible for slipperiness.


Deck Cleaning Guidance

On new and well-maintained decks, a simple sweep with a broom or clean with a stiff brush and mild soap solution is enough. Annual maintenance in spring or autumn will certainly go a long way to keeping your deck in tip top condition.

If a deck needs a deep clean to restore its appearance, take care when using a pressure washer so as not to damage the deck surface. Keep the lance a safe distance from the deck surface and set the pressure to the minimum level. Keep the head moving to avoid causing damage. Alternatively, use an attachment especially designed for cleaning decks. Once clean and dry, the topical application of a surface treatment can help with weather resistance or enhance the natural properties of the wood.

Detailed guidance on how to keep your deck in good condition is available to download from the TDCA website deck_cleaning_infosheet_5.pdf ( .  If you have any specific questions on this subject, please contact the Timber Decking and Cladding Association at Contact Us (


Assuring slip resistance on your deck

On commercial and public access decks where extra safety is required, it is essential to get the specification right from the outset.  The risk of a personal injury claim from a slip accident can be costly, time consuming and damaging to reputation. A ‘slippery when wet’ sign will not cover it!

The TDCA recommends selecting slip resistant timber deck boards such as the range manufactured by Marley Ltd, who are both a member of the TDCA and the United Kingdom Slip Resistance Group (UKSRG).

Marley’s CitiDeck® and AntiSlip Plus® products have been independently ex-factory tested against the standards set out by the UKSRG – using the HSE’s preferred method which is a pendulum test.  This testing generates a pendulum test value (PTV).  A minimum PTV value of 36 is required for the surface to be classed as a low slip potential.  CitiDeck® and AntiSlip Plus® comfortably exceed this minimum, scoring a PTV ranging between 60 to 80, depending if the surface is wet or dry.  A certificate from an accredited independent laboratory should always be available to support any product claims.

Third party accreditation

The TDCA operates DeckMark – quality schemes covering products, suppliers and installers. The DeckMark Product accreditation verifies the performance and longevity of materials that have been audited.

CitiDeck® and AntiSlip Plus® go one better and meet the requirements of the DeckMark Plus accreditation. DeckMark Plus is a complementary part of the DeckMark Product scheme. It identifies products that have undergone additional specific technical or safety evaluations by a national or international standard using recognised quantitative procedures.  In this case an enhancement of standard decking with antislip technology and slip resistance testing.

This article was written by the Timber Decking and Cladding Association (TDCA) in collaboration with Marley for the UKSRG website.

For guidance on the specification of antislip products please contact [email protected] or why not download Marley’s new Decking Specification Guide for free.


(Published 07/2022)





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