Yes, lumber produced on a portable sawmill can be used in a structural application, however it needs to be grade stamped!
Chuck Dentelbeck, President and CEO
Canadian Lumber Standards Accreditation Board
First, I encourage you to use lumber/timber in your next build or renovation. However, make sure the lumber/timber is graded and complies with your local building code. The impact of using lumber in a structural application that is not graded can be far reaching. Building officials will not approve your framing and may require the lumber to be removed or under the direction of a building engineer require the lumber to be inspected by a CLSAB Accredited Agency inspector, mortgage lenders may suspend construction loans and insurance providers may suspend coverage. The following information explains how lumber/timber produced on a portable sawmill can be used in your next build or renovation.
The National Building Code of Canada (NBCC) provides the minimum acceptable requirements to maintain the safety of buildings, with specific regard to public health, fire protection, accessibility and structural sufficiency. The NBCC is the model building code that forms the basis for all of the provincial building codes.
Since 1960, virtually all of the structural lumber produced in Canada has been marked with a nationally standardized, easy-to-read lumber grade stamp placed on the lumber or by an accompanying certificate when the final appearance of the wood is of crucial importance. These grade stamps or certificates identify the species, grade, grade rule, moisture content, facility, the Canadian Lumber Standards Accreditation Board (CLSAB) Accredited Agency that has overseen its grading, and any special processing the lumber has received. The guidance for this system is prescribed by “CSA-O141 – Softwood Lumber” as it designates softwood lumber manufactured in Canada as “Canadian Standard Lumber” where it meets the prescribed requirements for quality and uniformity. CSA-O141 also outlines the structure by which CLSAB must operate to ensure that the quality and uniformity of softwood lumber manufactured in Canada satisfies the “Canadian Standard Lumber” designation. The grading rules for “Canadian Standard Lumber” are approved by the CLSAB, however the National Lumber Grades Authority (NLGA) is responsible for writing, publishing, interpreting, and maintaining Canadian lumber grading rules and special product standards for softwood lumber. The NLGA also establishes and monitors structural lumber design values of Canadian species. These lumber design values are approved by the CSA-O86 Technical Committee on Engineering Design in Wood for use in Canada. CSA-O86 provides the criteria for the structural design and appraisal of structures or structural elements made from lumber graded in accordance with the NLGA Standard Grading Rules for Canadian Lumber and identified by a CLSAB Accredited Agency grade stamp as outlined in CSA-O141.
Softwood lumber may be designated as Canadian Standard Lumber if the following conditions are met:
- The lumber complies with the minimum requirements of CSA-O141,
- The lumber is graded in accordance with grading rules approved by CLSAB, and
- The lumber is inspected and identified in accordance with the regulations of CLSAB.
How to proceed before sawing
- Call your local building code office to determine the minimum requirements for the type and size of building you want to build.
- Contact a CLSAB Accredited Agency for assistance about:
- what the lumber should look like to meet the minimum requirements (grade, size and moisture content),
- what are acceptable wood species, and
- Generally, lumber produced from a portable sawmill is not surfaced/planed and/or dried and is sold as rough green. However, if the lumber will be surfaced/planed and/or dried it is recommended that a moisture meter be used to determine the moisture content of the material. As green lumber can be used in structural applications, however it must be dry or have a moisture content of less than 19% prior to finishing the build/renovation.
- Determine the minimum size (thickness and width) to cut the lumber/timbers according to whether it will be sold as rough green lumber or timber (Table 1), as surfaced dry or green dimension lumber (Table 2) or as surfaced dry or green timber (Table 3). The larger sizes for rough green and surfaced green takes into account shrinkage as the wood dries to its’ in service moisture content.
How to proceed after sawing
- Sort and then stack your lumber on a level surface according to the species, proposed grade and size. For example, place 2×4, 2×6, 2×8, etc. in separate stacks.
- Use dry spacers (stickers) at least 3/8 inch thick, placed no further than 4 inches from each end and approximately 2 feet apart in the row for every row of lumber. This will assist in reducing splits on the end and warps along the length.
- If you decide to sell the lumber as dry, cover the lumber and let it air dry to below 19% moisture. Periodically pull samples and using a moisture meter measure the moisture content.
- Schedule the visit of the CLSAB Accredited Agency lumber inspector.
- Arrange for at least two people to be available when the lumber inspector is on site to assist in moving material during the inspection.
- Provide documentation to the lumber inspector if specific requirements have been identified in the building plans by an engineer or building code official.
- The inspector will mark the face of each piece of lumber that meets the grade with a grade stamp. If you are having timber inspected the inspector will apply the grade stamp on the end of the timber and/or issue an inspection certificate.
The Grade Stamp
The grade stamp for the rough lumber produced on your sawmill will provide the following information.
- Registered Trademark of the CLSAB Accredited Agency
- Unique identification number of the inspector
- Grade – No. 2 or Stud
- Species or species or combination –
- S-P-F – which is comprised of the following species: White Spruce, Black Spruce, Red Spruce, Engelmman Spruce, Lodgepole Pine, Jack Pine, Balsam Fir and Alpine Fir grown in Canada.
- Hem-Fir (N) – which is comprised of Western Hemlock and Amabilis Fir grown in Canada.
- Fir-L (N) – Douglas Fir and Western Larch
- North Species – Any Canadian lumber species covered by the NLGA Grading Rules.
- Seasoning – moisture content at time of grading
- Dry – equal to or less than 19% maximum moisture content
- GRN – green – greater than 19% moisture content
- Grade rule used to grade the material – NLGA
Note – Additional information will appear on the stamp if a kiln has been used to dry the material to a moisture content equal to or less than 19% moisture content and/or the material was planed prior to grading.