ASHI Structural Systems 3 — Questions and Answers
Question 1: Which type of lumber defect MOST reduces the structural strength of a floor joist?
- A small knot near the edge in the neutral axis
- A large knot on the tension face near mid-span (Correct answer)
- Slight warping along the length
- Surface checking on the wide face
Correct answer: A large knot on the tension face near mid-span
A large knot on the tension face (bottom) at mid-span is the most critical location because that is where bending tension stresses are highest.
Question 2: What is the primary function of cripple studs in a window or door rough opening?
- To transfer header loads down to the foundation
- To support the header above the opening
- To carry loads from above the header to the trimmer studs (Correct answer)
- To provide nailing surface for the window frame only
Correct answer: To carry loads from above the header to the trimmer studs
Cripple studs above a header carry loads from the structure above down to the header, which then transfers them to the trimmer (jack) studs.
Question 3: During a home inspection, stair treads deflect noticeably underfoot. What is the MOST likely structural cause?
- Treads are made of softwood instead of hardwood
- Stringers are undersized or poorly attached (Correct answer)
- Risers are missing or open
- Handrail is loose at the wall bracket
Correct answer: Stringers are undersized or poorly attached
Stair stringers are the primary load-carrying members; if undersized or poorly fastened, the entire stair assembly will flex and deflect.
Question 4: A home inspector sees horizontal cracks in a poured concrete foundation wall. What do they typically indicate?
- Shrinkage during initial curing of the concrete
- Lateral soil or hydrostatic pressure exceeding wall capacity (Correct answer)
- Frost heave pushing up from below
- Settlement from inadequate footing depth
Correct answer: Lateral soil or hydrostatic pressure exceeding wall capacity
Horizontal cracks in poured concrete foundation walls are a serious sign of excessive lateral pressure from soil or water pushing against the wall.
Question 5: What is the role of hurricane ties (rafter ties) in a roof framing system?
- To connect ridge board sections together
- To mechanically fasten rafters to wall top plates resisting uplift (Correct answer)
- To brace the gable end wall against racking
- To hold roof sheathing to the rafters
Correct answer: To mechanically fasten rafters to wall top plates resisting uplift
Hurricane ties are metal connectors that anchor rafters to the wall plate, preventing uplift forces from wind from separating the roof structure from the walls.
Question 6: An inspector observes that a steel I-beam supporting the first floor has visible rust and section loss. Why is this a structural concern?
- Rust will contaminate the wood framing above it
- Section loss reduces the beam's moment of inertia and load capacity (Correct answer)
- The rust will accelerate corrosion in nearby plumbing
- Rust changes the thermal conductivity of the beam
Correct answer: Section loss reduces the beam's moment of inertia and load capacity
Section loss from corrosion reduces a steel beam's cross-sectional area and moment of inertia, directly lowering its bending and shear capacity.
Question 7: Which of the following best describes 'platform framing' as used in modern residential construction?
- A method where full-length studs run from foundation to roof
- A system where each floor level is framed independently on a platform (Correct answer)
- A technique using heavy timber posts and beams with infill panels
- A framing method with diagonal let-in bracing at corners
Correct answer: A system where each floor level is framed independently on a platform
Platform framing constructs each floor level as a complete platform before the next story's walls are erected, which is standard in modern residential construction.
ASHI Structural Systems 3
Which type of lumber defect MOST reduces the structural strength of a floor joist?