Structural, Framing, and Foundation Principles
Domain 7 - Structural, Framing, and Foundation Principles
This domain tests load path, foundation and framing details, and the IRC/IBC prescriptive limits that keep a structure standing. You should be able to trace gravity and lateral loads from roof to footing and recognize when a field modification is not allowed.
Loads and load path
Dead loads are permanent (structure, finishes); live loads are transient (people, furniture, snow); environmental loads include wind, seismic, and snow. The load path must be continuous: roof sheathing and trusses → wall framing and headers → floor framing → foundation walls and footings → soil. Interruptions require engineered connectors, beams, or posts. Braced wall lines and shear walls resist lateral loads; hold-downs and anchor bolts tie the frame down.
Foundations and framing limits
Footings must bear on undisturbed soil below the frost line - about 42 inches in Connecticut - and be sized for the load. Foundation walls need reinforcement, anchor bolts, and drainage. For a 2x10 joist (actual 9.25 inches), a hole may not exceed one-third of the depth (about 3 inches) and must be at least 2 inches from the top and bottom edges; notches may not exceed one-sixth of the depth (about 1.5 inches) and are not permitted in the middle third of the span, though end notches may be up to one-quarter depth. Engineered lumber must follow the manufacturer's span and hole charts - never cut an I-joist flange. Decks need a flashed, bolted ledger, lateral ties, proper footing size, and guards at 36 inches with balusters spaced under 4 inches.
Worked example
A plumber wants a 4-inch drain through a 2x10 floor joist at midspan. The hole exceeds the one-third limit and is too close to the edge, and midspan is the highest-stress zone. The correct response is to reroute the drain, use a soffit below the joists, or obtain an engineered detail - not to cut and hope.
Traps
Using nominal instead of actual dimensions; assuming any hole is acceptable; ignoring the middle-third notch rule; omitting ledger flashing; using wrong fasteners with treated lumber; and modifying engineered joists in the field.