An extract from TRADA’s Wood Information Sheet (WIS) Timber fencing, 2019. It includes advice on applications, design considerations, specification, durability and preservation, erection and workmanship, inspection and maintenance. To access the full WIS, please visit trada.co.uk
Timber has proved to be a particularly suitable material for a wide range of domestic and commercial fencing applications throughout the UK. Easily worked and readily available in a variety of types, shapes and sizes, it can last longer and perform better than many alternative materials – either in its natural form or with wood preservative treatment.
Timber fencing is diverse in its use and style, and performance requirements can vary considerably.
Fencing accounts for a significant proportion of the UK’s annual softwood consumption – approximately 14% in 2016. British softwoods are frequently specified, mainly lower strength species such as pine and spruce. Often these are faster grown than imported species from northern Europe. Hardwood species are also used – namely oak and sweet chestnut, with 30,000 green tonnes of UK material being used in 2016.
Timber is a natural product that does not benefit from exact dimensional or compositional consistency. It expands and contracts due to changing climactic conditions and is prone to splits (shakes), cracks (checks), knots, twisting, bowing, bending etc. When machine sawn, it can also exhibit saw marks, rough edges (with some discrepancies.
Specifying a fence
There are several considerations worth taking when constructing a new or replacing an existing fence, including resistance to the elements, desired service life and ease of maintenance.
Take into account the use of the fence along with the desired appearance to determine what type of fencing to choose
It is important to know the overall height, length and spacings of the fence, so that the supplier can provide the correct individual components of the structure. Guidance to the dimensions of certain components can be found in BS 1722.
BS 1722 refers to four distinct timber quality selection methods depending on the type of fence. For commercial use, it is advisable for a structural engineer to assess the structure and the possible loads that it may experience.
Where a certain colour, style or character is required, thought should be given to the appearance of the timber. This will have some impact on the timber species that is selected.