Structural Systems Flashcards

A home inspector identifies that a load-bearing wall has been removed and replaced with a header beam that appears undersized. What is the most likely consequence?

Answer: Excessive deflection or failure of the beam under load

An undersized header beam will deflect excessively or fail when supporting roof or floor loads that the original wall carried, potentially causing structural collapse.

Which foundation type is most susceptible to damage from expansive (clay) soils?

Answer: Poured concrete slab-on-grade

Slab-on-grade foundations are directly supported by the soil surface and are highly susceptible to heaving and cracking when expansive clay soils swell with moisture.

When inspecting a wood-framed floor system, what does excessive deflection under a live load most likely indicate?

Answer: Undersized joists, excessive span, or loss of section due to damage or notching

Excessive floor deflection (bounciness) typically means the joists are undersized for the span, have been weakened by notching or drilling, or are decayed.

What is the purpose of cross-bridging or blocking installed between floor joists?

Answer: To distribute loads and prevent joists from rotating or deflecting laterally

Bridging and blocking transfer loads between adjacent joists, prevent lateral rotation (tipping), and improve the overall rigidity of the floor system.

Diagonal cracking emanating from the corners of window or door openings in a masonry wall most commonly indicates:

Answer: Foundation settlement causing differential movement

Diagonal cracks at opening corners are a classic sign of differential foundation settlement, which causes the structure to rack and concentrate stress at the weakest points.

In platform (western) framing, each floor level is constructed as a separate:

Answer: Platform upon which the next wall section is built

Platform framing builds each floor as a horizontal platform before erecting the walls for the next story, distinguishing it from balloon framing where studs run continuously.

A home inspector observes that a wood beam in a basement has a significant vertical crack running along its length. This condition is typically:

Answer: A normal seasoning check caused by drying shrinkage, usually not structurally significant

Longitudinal checks (vertical splits) in solid-sawn lumber are typically seasoning cracks from moisture loss during drying and are generally not structurally significant unless deep or combined with other defects.