Shop precision-cut, kiln-dried CLS timber at NWTT - the go-to choice for stud walls, partitions and timber frame construction.
What is CLS Timber?
CLS stands for "Canadian Lumber Standard" — a specification for softwood timber that's been kiln-dried, machined with rounded edges, and cut to consistent, precise dimensions. Unlike rough sawn timber, CLS arrives ready to use straight from the pack, with no need for further planing or preparation. It's become a construction industry standard for internal timber framing thanks to its reliability, straightness and consistent moisture content.
Why Choose CLS Timber?
- Kiln-dried — reduces moisture content, minimising warping, twisting and shrinkage after installation
- Eased (rounded) edges — safer to handle and reduces the risk of splintering
- Consistent sizing — precision-machined dimensions make for faster, more accurate builds
- Lightweight yet strong — easy to work with while still providing reliable structural support for non-load-bearing applications
Common Uses for CLS Timber
- Stud walls & partitions — the standard choice for internal timber-framed walls
- Timber frame construction — used in wall panels, floor joists and roof structures
- Loft conversions — ideal for forming new partition walls and framework
- Soundproofing & insulation frameworks — provides a stable frame for insulation and acoustic boards
- General carpentry & joinery — used wherever straight, reliable timber sections are needed
CLS Timber Sizes
CLS is typically sold by "actual" size with the "ex" (sawn) size in brackets, since the finished, planed dimensions are always slightly smaller than the timber it's cut from. Common sizes include 75 x 50mm (ex 63 x 38mm) and 100 x 50mm (ex 88 x 38mm), covering the majority of stud wall and partition applications.
Frequently Asked Questions
What does CLS stand for?
CLS stands for Canadian Lumber Standard, referring to the machining and grading specification the timber is cut to.
Is CLS timber structural?
CLS is primarily used for non-load-bearing internal partitions and stud walls. For load-bearing structural work, graded timber such as C16 or C24 is generally required.
What's the difference between CLS and regular sawn timber?
CLS is kiln-dried and precision-machined with eased edges, giving consistent, ready-to-use dimensions — whereas rough sawn timber is unplaned and can vary slightly in size and moisture content.
What size CLS do I need for a stud wall?
75 x 50mm CLS is the most common choice for standard internal stud walls, while 100 x 50mm is often used where additional depth is needed for insulation or services.