Structural Systems Evaluation Flashcards

During a crawlspace inspection, you observe a floor joist that has a 3-inch diameter hole drilled through its center. The joist is a standard 2x8 dimensional lumber piece (actual dimension is 7.25 inches). According to building standards, what should be your primary concern?

Answer: The hole's diameter exceeds the maximum allowable size.

According to building standards, the maximum diameter of a hole bored in a dimensional lumber joist should not exceed one-third of the joist's actual depth. For a 2x8 joist (7.25 inches deep), the maximum allowable hole size is approximately 2.42 inches (7.25 / 3). A 3-inch hole exceeds this limit and can compromise the structural integrity of the joist.

A home inspector identifies a horizontal framing member in the upper third of the attic space, connecting opposing rafters near the ridge. What is the primary function of this component?

Answer: To prevent rafter separation from wind uplift forces at the ridge.

This component is a collar tie (or ridge strap). Its primary function is to connect opposing rafters in the upper third of the attic space to resist wind uplift forces that could pull the rafters apart at the ridge. Rafter ties, located in the lower third, are responsible for resisting the outward thrust of the rafters at the wall's top plate.

Which of the following observations would be the clearest indicator of foundation 'heave' rather than 'settlement'?

Answer: An upward bulge in the center of a concrete slab floor.

Foundation heave is the upward movement of a foundation due to expanding soil, often from excessive moisture. An upward bulge or dome shape in a concrete slab floor is a classic sign of heave, as the expansive soil pushes the center of the slab upwards. While the other options can be signs of foundation movement, they can be caused by either settlement (sinking) or heave, whereas a distinct upward bulge is specifically characteristic of heave.

According to the InterNACHI Standards of Practice for a residential inspection, which action is an inspector required to perform when evaluating the foundation and structural components?

Answer: Report on observed indications of possible foundation movement.

The InterNACHI Standards of Practice require an inspector to report on observed indications of possible foundation movement. This includes signs like sheetrock cracks, brick cracks, out-of-square door frames, and unlevel floors. The standards explicitly state that inspectors are not required to provide engineering services, move stored items, or determine the adequacy of foundation bolting or other structural systems.

During an inspection of a 1960s home, you notice that the exterior walls appear to be bowing outwards slightly, and there is a corresponding sag in the roof ridge line. In the attic, you see that the ceiling joists run perpendicular to the rafters and there are no other horizontal members connecting the base of opposing rafters. What is the most likely structural deficiency?

Answer: The absence of rafter ties is allowing the walls to spread apart.

Rafter ties are required to resist the outward thrust that roof loads place on the exterior walls. When ceiling joists are not parallel to the rafters, separate rafter ties (typically 2x4s) must be installed in the lower third of the attic to tie the base of the rafters together. The described symptoms—bowing walls and a sagging ridge—are classic indicators that this outward thrust is not being restrained due to the lack of rafter ties.

When inspecting visible framing members, an inspector notes a notch at the end of a 2x10 floor joist (actual depth 9.25 inches) where it rests on a support beam. The notch is 3 inches deep. What is the appropriate action for the inspector?

Answer: Recommend reinforcement, as the notch depth exceeds the allowable limit.

Building standards specify that a notch at the end of a dimensional lumber joist cannot exceed one-quarter of the joist's depth. For a 2x10 joist (9.25 inches deep), the maximum allowable notch depth is 2.31 inches (9.25 / 4). A 3-inch notch exceeds this limit, weakening the joist at a critical bearing point. Notches are prohibited in the middle third of the span.