SOLAS Carpentry cheat sheet

Nominal vs. actual lumber: a 2x4 is 1-1/2 in x 3-1/2 in; a 2x10 is 1-1/2 in x 9-1/4 in. Nominal size is used for span tables, actual size for layout arithmetic.

Board-foot formula: BF = (thickness in x width in x length ft) / 12. Example: a 2x8x12 = (2 x 8 x 12)/12 = 16 BF.

Plywood/OSB thickness shrinks by 1/32 in per sanding pass: 23/32 in sheathing substitutes for 3/4 in; 15/32 in for 1/2 in.

Nail sizing rule: nail length should be about 3x the thickness of the material being fastened; 16d (3-1/2 in) common nails for 2x framing, 8d (2-3/8 in) for 1x trim and 1/2 in sheathing.

Screws vs. nails: screws have greater withdrawal resistance but lower shear strength; nails (and lag screws) carry shear in structural connections, screws resist pull-out in trim, subfloor, and decking.

Joist hangers and connectors must be filled completely: every specified hole gets a fastener of the specified type and diameter; unused holes reduce capacity.

3-4-5 method for square layout: measure 3 ft on one leg, 4 ft on the other, and adjust until the diagonal reads 5 ft; scale proportionally (6-8-10, 9-12-15) for larger areas.

Stair layout: number of risers = total rise / target riser height, rounded up; unit run x (risers - 1) gives total run. Riser height must be uniform within 3/8 in across the flight.

Wall framing layout: studs at 16 in or 24 in on center, measured from the same reference edge; openings require king studs, trimmer (jack) studs, and a header sized by span and load.

Header sizing depends on span, load, and species/grade; doubling a header does not double capacity when the plies are not nailed together per the schedule.

Sheathing panel orientation: strength axis (long dimension) perpendicular to supports for floors and roofs; block all unsupported panel edges unless the panel rating permits otherwise.

Roof framing: common rafter length = run / cos(pitch angle); or use the framing square with unit rise per 12 in of run. Hip/valley rafters use the diagonal of the unit run.

Notching and boring limits: notches in the tension edge limited to 1/4 depth; holes limited to 1/3 of member depth and kept away from the tension edge per code.

Collar ties vs. rafter ties: collar ties resist uplift and sit in the upper third of the attic; rafter ties resist outward thrust and sit in the lower third, as low as possible.

Blocking and bridging between joists reduces deflection and transfers lateral load; solid blocking is required at bearing points and under concentrated loads.

Fire blocking is required in concealed spaces at floor/ceiling levels, at soffits, and at the top and bottom of stairwells to limit vertical flame spread.

Door swing and handing: a right-hand door hinges on the right when viewed from the pull side; specify handing, swing, and bore/strike locations before ordering prehung units.

Rough opening for a prehung door: unit width plus 2 in, unit height plus 2-1/2 in (verify manufacturer's spec; framed openings vary by jamb thickness).

Window rough opening: unit width plus 1/2 in to 1 in, height plus 1/2 in to 1 in, with shims at sill and jambs; flashing sequence is weather-resistive barrier, sill pan, then window.

Miter vs. butt joints: miters for outside corners and casing returns; butt joints for inside corners where seasonal movement is expected; cope inside corners on crown molding for tight fits.

Baseboard and casing reveal: keep a consistent reveal (typically 1/4 in to 3/8 in) between door/window frame and casing; measure reveals at multiple points before cutting.

Trim nailing: 4d or 6d finish nails for casing and base; set nails and fill; use 8d for thicker built-up trim. Pre-drill near ends to prevent splitting.

Stair baluster spacing: a 4 in sphere must not pass through any opening in a guard; handrail height is typically 34 in to 38 in above the nosing.

Door undercut and clearance: interior doors typically undercut 3/4 in to 1 in above finished floor for return-air and floor clearance; verify against flooring thickness.

Circular saw blade direction: teeth point forward and up at the front of the blade; the off-cut side is the waste side of the line.

Table saw kickback control: use the riving knife and blade guard, stand out of the kickback path, and use push sticks for stock narrower than 6 in.

Ladder angle rule: base set out 1 ft for every 4 ft of working height (75 degrees); extend 3 ft above the landing for access to a roof.

Fall protection trigger: in general construction, fall protection is required at 6 ft or more above a lower level; guardrails, safety nets, or personal fall arrest systems are acceptable.

Hearing and respiratory protection: power tools exceed 85 dBA at the operator position; use hearing protection and dust collection or a respirator rated for the dust (N95 minimum for wood dust).

Lockout/tagout: de-energize and lock out before servicing tools or equipment; verify zero energy state with a tester before work.

Material handling: stack lumber on dunnage, keep stacks stable and below 4 ft for manual handling, and never walk under a suspended load.

Jobsite housekeeping: clear walkways, secure cords overhead or in cable ramps, and keep a fire extinguisher rated for the hazard within reach of hot work.

Stud count estimate: (wall length in ft x 12 / spacing in in) + 1 for the end, plus 2 studs per opening (king and trimmer) and corner/intersection extras.

Plate material: top and bottom plates add 3x wall length for single top plate, 4x for double top plate; add 5-10% waste for cuts and defects.

Sheathing estimate: divide wall/roof area by 32 sq ft per 4x8 panel, then add 5-10% for waste and openings; deduct openings larger than 32 sq ft.

Concrete volume: volume = length x width x depth, all in feet; divide cubic feet by 27 for cubic yards; add 5-10% for over-excavation and spillage.

Inspection sequence: footing, foundation, framing (including shear and hold-downs), rough-in (electrical, plumbing, mechanical), insulation, then final. Do not cover work before inspection sign-off.

Egress window: clear opening of at least 5.7 sq ft, minimum 20 in width and 24 in height, sill no more than 44 in above the floor; check local amendments.

Guard and handrail code: guards required at 30 in or more above grade; guard height 36 in minimum for residential, 42 in for commercial; handrail 34-38 in.

Load path continuity: verify that gravity and lateral loads transfer continuously from roof to foundation through connectors, blocking, and shear panels; any break in the path is a structural deficiency.