Preservative treated

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Long-lasting, hard-wearing

At Marley, we pressure treat our timber decking on-site, using a water-based treatment. The timber is passed into a treatment vessel and undergoes a vacuum-pressure impregnation process, enabling the preservative treatment to be forced into the timber cells.   

It's vital that softwood species, such as European Redwood used by Marley, are pressure treated before installation. This extends the durability of the product, protecting it from rot, fungi and insect attack, giving it a longer life.

The amount of preservative required depends on the final use of the product. All our Marley timber decking is preservative treated using Naturewood® to attain Use Class 3 as standard and complies to BS 8417.

Marley Timber Decking | preservative treated
Marley timber decking
Marley timber decking

The Use Class system

We're supporting the Timber Trade Federation (TTF) and Timber Decking and Cladding Association (TDCA) in raising awareness of the Use Class system and why it's important to choose the correct one for the intended product usage.

The Use Class system governs the amount of preservative protection applied to timber. For timber decking, typically the following Use Classes apply: 

Use Class Service situation Main biological threat Decking applications


  • External uncoated: above ground
  • Exposed to frequent wetting
  •  Fungal decay
  • Landscaping and decking timbers not in contact with the ground


  • In contact with ground or freshwater
  • Permanently exposed to wetting and/or providing exterior structural support
  •  Fungal decay
  • Decking posts, joists and sub-structures; jetties and boardwalk support

Information provided courtesy of the Wood Protection Association. Find out more by visiting them at

Desired service life

In addition to the Use Class of treatment, timber is also treated to a desired service life. Within BS EN 599-1 recommendations for penetration and retention are provided to achieve a desired service life of 15, 30 and 60 years.

This desired service life does depend on a number of factors including the quality of the treater and treatment, design and installation, maintenance regime and the conditions the timber is exposed to.

Therefore, this timescale is not a guarantee of performance but an indication of the expectation against which the recommendations for treatment are drawn up, assuming good design and normal conditions of use.

If you're interested in finding out more about Use Class and desired service life. Take a look at our Use Class blog below.

Use Class blog

Read our blog explaining Use Class treatment for timber decking. 

Use Class guide

For more information on the Use Class system download the WPA guide below.

Marley timber decking
Marley timber decking
Other benefits of Marley timber decking
The Marley timber decking range