InterNACHI Structural Systems Evaluation 2 — Questions and Answers
Question 1: When inspecting a wood-frame house, an inspector notices the floor joists are notched at mid-span to accommodate plumbing. What is the primary concern?
- The notch reduces shear capacity at the most critical bending zone (Correct answer)
- The notch may allow moisture intrusion from the pipes
- Notches at mid-span are acceptable if less than one-third of joist depth
- The plumbing pipes may corrode the wood over time
Correct answer: The notch reduces shear capacity at the most critical bending zone
Notching floor joists at mid-span significantly reduces their bending and shear capacity because mid-span is where bending stress is highest.
Question 2: An inspector observes stair-step cracking in a brick veneer wall near a window corner. This pattern most likely indicates:
- Thermal expansion of the brick
- Differential foundation settlement (Correct answer)
- Improper mortar mix during construction
- Normal curing shrinkage of new brick
Correct answer: Differential foundation settlement
Stair-step cracks following mortar joints near openings are a classic sign of differential foundation settlement causing racking forces in the masonry.
Question 3: Which condition would MOST concern an InterNACHI inspector when evaluating wood posts in a crawl space?
- Posts are pressure-treated lumber
- Posts are sitting directly on the soil without footings (Correct answer)
- Posts have a slight taper from top to bottom
- Posts are spaced 8 feet apart
Correct answer: Posts are sitting directly on the soil without footings
Wood posts in direct contact with soil will wick moisture and are highly susceptible to decay and insect damage, compromising structural support.
Question 4: During a home inspection, an inspector finds that the ridge board in the attic has a significant sag. The MOST likely structural cause is:
- Inadequate collar ties or rafter ties allowing the rafters to spread (Correct answer)
- The ridge board is too wide for the span
- Snow load has permanently compressed the ridge board
- The attic ventilation is insufficient
Correct answer: Inadequate collar ties or rafter ties allowing the rafters to spread
A sagging ridge board typically results from rafter spread caused by missing or inadequate collar ties, allowing the roof structure to push outward and down.
Question 5: An inspector identifies that a load-bearing wall has been removed in a residence without a header installed. What is the most immediate structural risk?
- Increased energy loss through the opening
- Transfer of loads directly to floor joists not designed for point loads (Correct answer)
- Cosmetic cracking of drywall above the opening
- Reduced fire resistance rating of the wall assembly
Correct answer: Transfer of loads directly to floor joists not designed for point loads
Without a header, concentrated point loads from above transfer directly to the floor system at locations not engineered to handle them, risking structural failure.
Question 6: When evaluating a concrete block (CMU) foundation wall, an inspector notices horizontal cracking near mid-height. This type of crack most often results from:
- Vertical settlement of the foundation footing
- Lateral soil or hydrostatic pressure bowing the wall inward (Correct answer)
- Shrinkage of the concrete blocks during curing
- Freeze-thaw cycling affecting the mortar joints
Correct answer: Lateral soil or hydrostatic pressure bowing the wall inward
Horizontal cracks at mid-height of CMU foundation walls are a serious sign of lateral earth or hydrostatic pressure causing the wall to bow inward.
Question 7: What does the term 'bearing capacity' refer to in the context of a home inspection structural evaluation?
- The maximum load a structural member can carry before deflection
- The ability of the soil or structural member to support imposed loads without failure (Correct answer)
- The weight of the building's structural frame itself
- The resistance of a foundation to frost heave
Correct answer: The ability of the soil or structural member to support imposed loads without failure
Bearing capacity is the maximum load per unit area that soil or a structural element can support without experiencing shear failure or excessive settlement.
InterNACHI Structural Systems Evaluation 2
When inspecting a wood-frame house, an inspector notices the floor joists are notched at mid-span to accommodate plumbing.
What is the primary concern?