Canadian Lumber Standard

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]}

History

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]

Usage

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]

Details

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]