Structural Systems
Load path first
Every structural question comes back to one idea: load path. Roof and ceiling loads travel through rafters, the ridge, ceiling joists and bearing walls, then through headers, posts, beams and footings into the soil. Ask whether each element is directly supported, and whether a later alteration removed something that was carrying load.
Foundation types and what cracks mean
Know slab-on-grade, raised/crawlspace with piers or stem walls, full basement, and pile foundations. Footings must bear below frost depth. A hairline vertical crack in a poured wall or slab is usually shrinkage during curing. Stair-step (diagonal) cracks in brick or block, wider at one end, suggest differential settlement. Horizontal cracks with a bowed wall suggest lateral soil pressure and are significant. Cracks radiating from the corners of door and window openings indicate movement at that opening.
Framing and alteration traps
Questions love modified framing: a joist notched too deep, a post removed to "open up" a room, truss chords cut for attic storage, a partition carrying a joist it was never designed for. For solid-wood joists, a useful rule of thumb is notch depth no more than one-quarter of the joist depth on bearing walls and one-third elsewhere, with holes no larger than one-third of the depth, kept at least 2 inches from the top and bottom edges and out of the cantilever.
Worked example
A crawlspace pier shimmed with wood blocks sitting on bare soil: report the soil contact, the unapproved shim and the missing footing as conditions needing evaluation by a structural professional, without declaring the house unsafe.