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Joists
Sawn Lumber Sizes
Sawn lumber used as joists ranges in common thicknesses from 38 to 88 mm (2"-4" nominal) and in depths from 89 to 286 mm (4" to 12" nominal). They are the most economical and easily installed secondary framing members for floor and roof construction in spans up to approximately 23 ft. (7m)
Species and Grades
In the 38 mm (2 in. nominal) thickness, the most readily obtainable material is the No.1 or No.2 grade. S-P-F, Hem-Fir, and D.Fir-L species are most likely to be stocked by lumber yards, but Northern Species may also be on hand.
MSR Grades
Some Machine Stress-Rated grades are also readily available in widths up to 184 mm (8" nominal) ; wider material may not be available and suppliers tend to carry a limited range of grades. Joists in 38 mm (2" nominal) thickness can usually be obtained kiln-dried (specify S-Dry) to a moisture content of 19% or less. In the 3 and 4 in.nominal thicknesses, choices of species and grade is more limited. These thicknesses are generally surfaced in the green condition (S-Grn) and are not obtainable as MSR lumber.
Multi-ply Joists
The program includes a database of 2" (nominal) thick joists to be used in multi-ply applications, limiting the number of plies to 2. This allows you to double up the joist members to deal with heavy loading requirements.
Stud Walls
Sizes
Lumber used in stud wall systems has a common thickness of 38 mm (2" nominal)) and ranges in depth from 89 to 184 mm (4" to 8" nominal). Stud grade lumber, however, ranges in depths from 38 to 140 mm (2" to 6" nominal) The smaller sizes are used mainly in interior partitions. For depths greater than 140mm (6 in.nominal), a grade other than "stud" must be specified.
Sheathing Requirements
In stud walls the members are spaced no farther apart than 600 mm (24") to take advantage of load sharing. Usually the spacing is 400mm (16".) or less. Stud wall systems are typically sheathed by plywood, waferboard, oriented strand board (OSB) or drywall (GWB). The sheathing is nailed to the narrow faces of the studs (on at least one side) along the entire length of the stud, thereby preventing buckling about the weak axis.
Note: Studs are susceptible to buckling if heavy loads are applied prior to installation of the sheathing.
Multi-ply Wall Studs
The program includes a database of 2" nominal wall studs to be used in multi-ply applications. This allows you to for example double up the stud members to deal with heavy loading requirements.