Using Ungraded Lumber in Farm Buildings
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In Ontario, the use of ungraded lumber in some farm building projects is an acceptable practice. A woodlot can be a source of potentially inexpensive lumber for smaller farm buildings and may help reduce building capital costs.
This factsheet summarizes the difference between graded and ungraded lumber, the specific requirements to permit the use of ungraded lumber and key considerations owners and builders should address prior to starting a building project with ungraded lumber.
Structural lumber is graded according to the National Lumber Grades Authority (NLGA) and bears the stamp of the agency accredited by the Canadian Lumber Standards Accreditation Board (CLSAB) under contract with the manufacturing facility. The stamp will bear the agency's mark, the facility number, the grade rule used and the grade of the lumber, the species, moisture content and phytosanitary treatment. The Ontario Forest Industries Association (OFIA) oversees NLGA grading and inspection in Ontario. An example of a grade stamp is shown in Figure 1.
Throughout Canada, commercial lumber is graded by the manufacturer that produces it. Facilities producing commercial lumber are audited by an accredited agency of the CLSAB. More information regarding commercial lumber manufacturers can be found on the Ontario Lumber Manufacturers Agency (OLMA) website.
Graded lumber meets the minimum requirements for strength, stiffness, moisture content and other qualities for a particular grade and species of lumber. Published design values can be used to carry out the structural design of wood structures using graded lumber.
Figure 1. An example of a grade stamp. This lumber has been graded in accordance with NLGA grading rules by the Canadian Lumbermen's Association and was produced by Mill number 869. The lumber is a Spruce-Pine-Fir species, kiln dried (KD), heat treated (HT) and assigned a Number 2 grade.
In accordance with the 2012 Ontario Building Code, ungraded lumber means lumber that has not been grade-stamped to indicate its grade, as determined by the NLGA "Standard Grading Rules for Canadian Lumber", but that meets the following visual traits:
Design of wood structures using ungraded lumber can be carried out by a qualified designer using the tables provided in Supplementary Standard SB-11 of the Ontario Building Code.
The 2012 Ontario Building Code allows the use of ungraded lumber in farm buildings under a specific set of requirements:
Where one or more of the requirements cannot be met on a particular project, owners and builders can consider having the lumber graded. The Ontario Forest Industries Association and the Ontario Lumber Manufacturers Agency are capable of applying NLGA grading rules. These organizations have graders who travel to rural properties with portable sawmills and provide on-site inspection for grading and grade stamping the lumber to NLGA Standard Grading Rules. Both dressed and rough-sawn lumber can be graded. The fee for a licensed grader is on a per day basis plus expenses (e.g., mileage, meals, accommodations). For more information, contact the OFIA or OLMA.
To construct a smaller farm building using ungraded lumber from a woodlot, consider the following early in the planning process:
It is permitted to use ungraded lumber to construct smaller, single storey farm buildings in Ontario, provided certain requirements are met. Where the requirements cannot be met, an owner can have the lumber graded by a licenced grader for use in building construction. In either case, a woodlot is a source of potentially inexpensive lumber which can help reduce building capital costs. Careful planning and good communication with the local municipality, builder, designer and sawmill is essential to ensuring a successful building project.
This factsheet was revised by Steve Beadle, P. Eng., Engineering Specialist, Livestock Structures & Equipment - Swine and Sheep, OMAFRA, Ridgetown and reviewed by Vicki Hilborn, P. Eng., Engineering Specialist, Civil Systems, OMAFRA, London and Matt Farrell, CET, CBCO, Chief Building Official, Township of Huron-Kinloss.
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