Wood, Cold-Formed Steel, and Rough Carpentry
Wood framing
Understand lumber grading, species groups, moisture content, and nominal versus actual dimensions (2x4 is 1.5 x 3.5 in). Know platform versus balloon framing, stud spacing, headers, and load paths. Traps: assuming nominal dimensions in calculations, and confusing dimensional lumber with engineered products.
Engineered wood
Study LVL, glulam, I-joists, and OSB sheathing. Know span ratings, web stiffeners, and bearing requirements. I-joists cannot be notched in the flange and require proper bearing at ends.
Fasteners and connections
Distinguish nails, screws, bolts, and structural connectors (joist hangers, straps, hold-downs). Understand withdrawal versus shear values, edge distance, and the role of hurricane ties in uplift resistance.
Cold-formed steel
Know stud gauges (e.g., 33 mil, 43 mil), track versus stud, bridging, and screw spacing. CFS is noncombustible and dimensionally stable but buckles, so bracing matters.
Rough carpentry
Understand sheathing installation, blocking, and subflooring. Traps: missing blocking at concentrated loads, and using the wrong sheathing thickness for the span rating.
Worked example
A wall 20 ft long with studs at 16 in on center: number of spaces = 240/16 = 15, so studs = 15 + 1 = 16, plus corners and openings. Trap: forgetting the extra stud at each end and each opening.
Rule of thumb
Always use actual dimensions for area and volume, and add one stud per wall end and per opening side.