Creosote is a robust, long-lasting, efficacious wood preservative that has been used for over 150 years for the preservation of timber used in heavy duty applications, successfully protecting against the threat of decay and insect attack. However, its safety and environmental credentials have been under review for quite some time across Europe.

For a number of years the continued use of Creosote under the EU Biocidal Products Regulation (BPR) has been restricted to specific professional and industrial applications. The BPR authorisation is an extremely thorough risk assessment of the active ingredients, the formulated product and the treated article. The BPR requires years of rigorous testing, analysis, and assessment.


At the end of September 2022, EU Member States voted on the renewal of the authorised applications for timber treated with Creosote. The majority of Member States voted in favour of restricting authorisation even further. Moving forward, the only authorised continued use for Creosote treated timber across EU Member States is for railway sleepers and utility poles for electricity and telecommunications.

This means that Creosote-treated timber used for heavy duty landscaping, such as agricultural fencing, will be banned from being sold in spring 2023. The positive vote to ban the use of Creosote to treat fence posts across EU Member States was made on the grounds that suitable and sufficient alternatives are available.

Following Brexit, the UK is exempt from the further restrictions on Creosote-treated timber and it can still be sold for heavy duty landscaping applications after spring 2023, as well as for railway sleepers and utility poles.


For many in-ground applications, there are a number of industrially applied high-pressure, water-based treatments readily available on the market. The level of protection they will provide will depend on a number of factors, including timber species treated, how the timber is prepared prior to the high-pressure treatment process and the actual treatment used. In addition, there are some oil-based products available.

Of course, there are also other substitute products, including concrete, steel and composite. There is a place for all materials, but it is the job of the timber industry to educate the market on why timber as a renewable, low carbon material should be the first choice. To help with this, many trade associations and businesses are investing in Life Cycle Analysis (LCA) and Environmental Product Declarations (EPDs).


At Arxada we are able to offer both a water-based, high-pressure treatment and an oil-based treatment through Tanalith E and Tanasote. With two alternatives to traditional Creosote treatments being available, we are often asked what the differences are. Essentially the difference is in the desired service life of the end-use applications.

As a high performance, oil-based copper wood preservative, Tanasote is better suited to protect industrial timbers, such as railway sleepers and utility poles, and hard landscaping timbers where an extended service life beyond 30 years is required. For domestic purposes, timber treated with Tanalith E is more appropriate taking into account cost and longevity. Tanalised timbers for exterior use provide a desired service life of 15 to 30 years, depending on end-use application.


Currently Tanasote is the only oil-based wood preservative approved under the BPR. All of the active ingredients used in Tanasote S40 are approved for wood preservative use in Europe, with no exclusion criteria met, and no candidates for substitution. The product itself has passed all necessary risk assessments of the BPR for the treatment of timbers to be used in above ground (Use Class 3) and in ground (Use Class 4) industrial heavy duty applications, and is currently authorised for use in 20 Member States, until at least 2031.

Substantial investment in the performance testing of Tanasote beyond the required industry standards has been made. Both EN 252 and EN 599-1:2009 + A1:2013 are typically used to predict a service life of between 15 to 30 years. For heavy duty timbers it’s imperative that a longer service life is provided, leading Arxada to engage in additional testing in high humidity and aggressive field test sites, as well as laboratory fungal studies. One such test is the accelerated field stake test using the Fahlstrom stake test method.

The Fahlstrom stake test method is an accepted fast approach to determine decay in a real-world environment through the use of thin stakes. The combination of a very small size and harsh conditions at the aggressive, high humidity field site in Florida, has enabled us to evaluate the long-term performance of Tanasote-treated timber compared with CCA as the reference preservative. In this testing we went beyond the standard CCA retention to demonstrate performance against preservative retention known to deliver a service life of 40 years. In addition, we also compared Tanasote with a water-based copper wood preservative treatment.

To provide confidence in our test performance data, Tanasote efficacy data has been reviewed by BM TRADA. Plus, we have also engaged in full scale trials of Tanasote with commercial partners across Europe, covering railway sleepers, utility poles, equestrian fencing and agricultural fencing.

Effective wood preservation, with a long-service life against wood destroying fungi and insect attack, means that treated timber can store carbon for decades longer than untreated decay-susceptible wood. Whilst Creosote has such a long history of doing this, its use will be further restricted, if not withdrawn at some point in the future. Creosote is classified as toxic, persistent, bio-accumulative and carcinogenic and meets the exclusion criteria for biocidal active substances.

If wood is to be kept as a primary material of choice in important agricultural and industrial applications, the industry needs to be bold and adopt modern and innovative BPR-authorised alternatives. For the market to switch to alternative wood protection technologies, performance data and investment in life cycle analysis is crucial. Future wood protection technologies should confidently deliver both high performance and a lower environmental impact than other materials, such as steel and concrete.

At Arxada we have invested in assessing the environmental impact of Tanasote-treated timber, encompassing LCAs and EPDs. The LCA results are available on our website – visit – and we are progressing with the EPD project.

Tanasote® S40 is a BPR authorised product. Use wood preservatives safely. Always read the label and product information before use.