InterNACHI Structural Systems & Components 5 — Questions and Answers
Question 1: What is the structural significance of 'hurricane ties' or 'rafter ties' used in roof framing?
- They improve the aesthetic appearance of roof framing
- They provide a mechanical connection between rafters and wall top plates to resist uplift forces (Correct answer)
- They reduce the spacing required between rafters
- They allow roofs to be built without ridge boards
Correct answer: They provide a mechanical connection between rafters and wall top plates to resist uplift forces
Hurricane ties are metal connectors that mechanically fasten rafters or trusses to the wall top plate, providing a continuous load path to resist wind uplift forces.
Question 2: What type of foundation is typically used on steep hillside lots to reach stable soil while minimizing excavation?
- Slab-on-grade
- Pier and grade beam foundation (Correct answer)
- Pressure-treated wood foundation
- Full perimeter basement
Correct answer: Pier and grade beam foundation
Pier and grade beam foundations use drilled piers or piles to reach stable soil on steep slopes, with grade beams spanning between piers to support the structure above.
Question 3: A home inspector observes that floor joists run parallel to one side of a bathtub but the subfloor feels soft and spongy near the tub. What is the most likely structural cause?
- The subfloor is the wrong thickness
- Water damage from tub or plumbing leaks has caused decay in joists and subfloor (Correct answer)
- The joists are spaced too far apart
- The bathtub is too heavy for the floor system
Correct answer: Water damage from tub or plumbing leaks has caused decay in joists and subfloor
Soft, spongy subfloor near a bathtub most commonly indicates chronic water intrusion from the tub or plumbing has caused wood decay in the subfloor and underlying joists.
Question 4: What is a 'moment frame' in structural engineering, and when might a home inspector encounter one?
- A frame used to support a picture or mirror
- A rigid structural frame designed to resist lateral forces through beam-column connections rather than diagonal bracing (Correct answer)
- A temporary frame used during construction
- A frame built around a fireplace opening
Correct answer: A rigid structural frame designed to resist lateral forces through beam-column connections rather than diagonal bracing
A moment frame resists lateral loads (wind/seismic) through rigid connections between beams and columns; inspectors may encounter them in garages with large openings or seismically engineered homes.
Question 5: When inspecting a wood-framed floor system, what does excessive deflection (bounciness) most commonly indicate?
- The subfloor adhesive has failed
- Undersized or over-spanned joists, or loss of joist strength due to damage (Correct answer)
- The floor finish material is too heavy
- Normal characteristic of wood-frame construction
Correct answer: Undersized or over-spanned joists, or loss of joist strength due to damage
Excessive floor deflection typically indicates joists that are undersized for their span, over-spanned, damaged by moisture, insects, or improper notching/boring.
Question 6: What does 'out of plumb' mean when describing a wall condition during a home inspection?
- The wall lacks plumbing rough-in
- The wall is not vertically straight — it leans or tilts from true vertical (Correct answer)
- The wall has no insulation
- The wall is not load-bearing
Correct answer: The wall is not vertically straight — it leans or tilts from true vertical
An out-of-plumb wall deviates from vertical, which can indicate foundation settlement, framing failures, or inadequate lateral bracing.
Question 7: Which condition should prompt a home inspector to recommend further evaluation by a structural engineer?
- Minor weathering on exterior trim
- Significant diagonal cracks at window or door corners combined with sticking doors and windows (Correct answer)
- Small nail pops in drywall
- Slightly uneven tile grout lines
Correct answer: Significant diagonal cracks at window or door corners combined with sticking doors and windows
Diagonal cracks at corners of openings combined with doors and windows that stick or don't operate properly are classic signs of structural movement requiring professional evaluation.
InterNACHI Structural Systems & Components 5
What is the structural significance of 'hurricane ties' or 'rafter ties' used in roof framing?