Canadian Lumber Standard, typically abbrievated as CLS, is a type and standard/grade of processed and sawn lumber (timber) used in many countries.[1] [2] [3] [4] [5] [6]
CLS was originally a product of Canada used in the construction of sturdy timber-framed houses as rated by the Canadian Lumber Standards Accreditation Board (CLSAB).[1] [2] Following the end of the Cold War it was increasingly used by manufacturers in Baltic countries as a reference grade for export to the UK and other Western European countries.[1] For these reasons, Latvian CLS, Swedish CLS and other European graded timber are now available, despite not originating from Canada.[1] Most CLS now originates from Europe, including Scandinavia.[6]
CLS is primarily used in internal construction because of is strength and durability.[6] As such, CLS is widely utilised as a general standard for timber suitable for wall studs, DIY and other construction projects, including housebuilding.[1] [4] [7] It is very commonly employed in conventional timber frames for roofs, lofts and attics.[8] It is typically used in the UK for timber wall studs.[9]
For use outside, CLS timber should be treated for external use.[4]
CLS timber is kiln-dried and is white wood.[9] Tree sources include Fir, Pine and Spruce.[10] [6]
CLS is planed and fished with eased or rounded edges.[9] [11] CLS timber is commonly graded at two strengths, C16 or C24.[9] C24 is the stronger and is typically more expensive.[10]
It is often pressure treated and may also be treated with pesticides to stop insect and fungal growth.[5]