What is CLS Timber? - Armstrong Cheshire
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What is CLS Timber?

What is CLS Timber?

Aaron Stretton |

In recent years, the use of CLS timber has grown in popularity in the UK, and it is often the go-to option for both timber framing and constructing 'stud' or 'studwork' internal walls. So what is CLS? The name is born from the Canadian market where it was originally created, with the abbreviation standing for ‘Canadian Lumber Standard’.

It was manufactured in Canada, primarily being used for building timber frameworks for home construction and chosen for its durable and robust properties. Here in the UK, the version of CLS in use is sourced most commonly from Scandinavian or European softwoods.

Typical trees used  for Studwork are spruce, pine and fir, all of which are kiln-dried for increased stability. The wood is treated and then planed to ensure smooth rounded edges, finishing the product and delivering reliably accurate tolerances.

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What is CLS timber used for?

In the UK, CLS timber can be found being used most often in  framing, timber framework construction, and building internal partitioning.

CLS timber is also a perfect fit for constructing internal stud walls due to the fact that it comes fully surfaced on each of its four facets and is rounded smoothly at the edges.

Available in a wide selection of sizes to suit a variety of applications, CLS timber is an exceptionally versatile product. Machine planed and finished on all sides and edges, it can also help achieve the perfect finish.


Why select CLS?

It is an option worth considering for your building work for a number of reasons. An easy-handle choice, CLS wood’s rounded edges and corners make it safe and simple to move around from one place to another.

Its strength means CLS wood is a reliable choice for construction for everything from timber framing to internal applications like partitioning off rooms.

Far more durable than many other woods, it can also prove cost efficient over time. Offered in many different widths and lengths, it  can be very convenient keeping cutting work to a minimum along with wasted wood adding to its value.

The manufacturing of CLS timber is responsibly sourced for the benefit of the environment and is regulated, which means that the prices keep competitive.

Can CLS timber be used outside?

While common woods used in this type of timber, like pine and spruce, are not ideal naturally for use externally, the attributes of CLS can be, if treated. 

The popularity of CLS comes in part from its reputation for providing surface finishes that are easy on the eye and simplify the process of applying preservatives, stains and paint.

This quality of CLS timber means that if you do decide to use it outside, it will be very easy for you to treat it with extra protection against the elements. Properly treated timber that is well maintained is capable of lasting a lifetime. Preservatives that repel water, paint that includes protection from UV rays and sealers will all adhere well to CLS and are readily available in a clear format.

While it can be used outdoors, it’s important when purchasing  to understand the different grades it’s available in.

Conforming to the British Standard for timber structures EN 14081-1:2005, CLS wood is graded by its structural strength. CLS timber comes in two grades - C24 and C16. Both of these woods typically resemble each other in appearance, but the C24 grade timber is stronger.

C16 graded CLS timber is better suited to indoor construction such as creating partitioning and internal walls. It is not the best choice for use outside as it might not be able to withstand against severe climate conditions.

To achieve your desired results, it’s important to always ensure you pick the right grade for your purpose when it comes to buying CLS timber.

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