Carpentry, Wood Framing, and Finish
Framing questions test structural logic and code basics. Understand the load path: roof loads travel through rafters/trusses to walls to beams/columns to foundation. Know platform framing versus balloon framing and why platform framing dominates modern construction. Understand stud spacing (16 in or 24 in on center), headers over openings, and king/jack/cripple studs.
Master floor and roof framing terms: joists, girders, subfloor, sheathing, rafters, ridge, collar ties, and hurricane/rafter ties. Know the purpose of blocking, bridging, and shear walls (resist lateral loads). Understand wood shrinkage and moisture content - lumber is graded at 19% MC or less for framing; green lumber shrinks and can cause finish problems.
Know finish carpentry basics: trim, door/window installation, cabinet layout, and tolerances. Understand fasteners and how to avoid corrosion (galvanized or stainless near treated wood). Know that pressure-treated wood is required near concrete/masonry and where exposed to moisture, and that connectors must be rated for treated lumber.
Worked rule of thumb: For joists spaced 16 in o.c., each joist supports a 16-in-wide strip. To count joists for a 24-ft span at 16 in o.c.: 24 ft = 288 in; 288 ÷ 16 = 18 spaces, so 19 joists. Always add one for the end.
Traps: forgetting the extra joist/stud; using untreated wood against concrete; undersized headers; ignoring lateral bracing; confusing collar ties with rafter ties.