A guide to choosing the right timber for your job.

 As of June 2004, CCA  (copper, chrome, arsenic) treated timber was banned by the European Commission (directive 76/769/EEC). This had a detrimental impact on the fencing industry, as it was unknown at the time what the results of the new treatment would be. It is now known that the use of mixed species timber for ground contact is not viable due to the uptake of the tanalising fluid by the cell structure of the timber. (An exception to this would be incised timber.) After 15 years of research and development, there is now a classification table to guide and assist in purchasing of treated timber.

Which Use Class to use

UC 1 Internal Dry e.g. upper floor joists
UC 2 Internal Risk of wetting e.g. tiling battens
UC 3.1 Outdoors Coated above ground e.g. decorated cladding
UC 3.2 Outdoors Uncoated above ground e.g. fencing rails
UC 4 Outdoors direct contact Direct contact with soil or freshwater e.g. fence posts 

As a result of this, we offer ground contact timbers in 3 differing formats to try to cover different budgets and applications.


Tanalised UC 3.2 - These posts are normally mixed species or spruce. We recommend these posts for temporary fencing only. Life expectancy 5 - 6 years

Tanalised UC 4 - These ground contact timbers are produced by carefully selecting Pine softwood (Redwood – species Pinus Sylvestris) which has been either air dried/seasoned or kiln dried to a moisture content of 28% or below. The timber is slow grown Northern European Pine is the ideal species for this pressure treatment process, allowing the treatment to penetrate deep into cells of the wood and achieve the criteria set within the BS8417 (British Standard) treatment guidelines for the 15-year warranty. Through a combination of selecting 100% Redwood for our ground contact timbers, careful kiln-drying to ensure an appropriate moisture content and the latest generation of preservative treatment Hartlington Fencing can offer a range of high performance treated timbers. Life expectancy 15 years

Creosoted UC4 - This is the same process to the above class 4 treatment. The only thing different is that the posts are treated with Creosote rather than tanalising fluid. These posts have a 20-25 year life expectancy.