CLS Timber

CLS (Canadian Lumber Standard) timber is typically used for internal stud walls and framing. It is planed on all four sides with eased (rounded) edges, making it easy to handle and precise to work with.

The main difference is that CLS refers to the shape and finish of the wood, while C16 refers to its structural strength.

• CLS (Canadian Lumber Standard) is planed smooth with rounded edges, making it easy to handle for internal stud walls and framing.
• C16 is a strength grade. It tells you the wood has been kiln-dried and tested to ensure it can support specific loads in construction.

Yes. In fact, most high-quality CLS timber sold in the UK is also graded to C16 strength. This means the timber has the smooth, rounded finish of CLS (ideal for interior framing) while also meeting the legal strength requirements for structural building projects. If your project is structural, always check that your CLS carries the C16 or C24 stamp.

The short answer is yes, but only temporarily. CLS (Canadian Lumber Standard) is primarily designed for internal use. Because it is kiln-dried to a low moisture content, it is highly stable for indoor framing, but it reacts poorly to prolonged exposure to the elements.