CLC Structural Carpentry & Framing Flashcards

When framing a staircase rough opening, the trimmer joists on each side serve to:

Answer: Carry the header and transfer loads around the opening

Trimmer joists run parallel to the regular joists and support the double header that frames around the stair opening, redirecting floor loads around the hole.

What is the maximum allowable stair riser height per IRC residential code?

Answer: 7-3/4 inches

IRC R311.7.5.1 limits maximum riser height to 7-3/4 inches for residential stairs, with a maximum variance of 3/8 inch between any two risers.

In engineered lumber design, LVL stands for:

Answer: Laminated Veneer Lumber

LVL (Laminated Veneer Lumber) is manufactured by bonding wood veneers together under heat and pressure, producing a high-strength, dimensionally stable structural member.

Which factor most affects the allowable span of a floor joist?

Answer: Species and grade of lumber, joist depth, and spacing

Allowable span tables consider lumber species, grade, size (depth), and on-center spacing together — changing any one of these variables changes the allowable span.

What is the primary reason for installing solid blocking at the ends of floor joists where they bear on a beam?

Answer: To prevent joist rotation and maintain spacing

Solid blocking (or rim joists) at bearing points prevents joists from rotating under load and keeps them plumb, maintaining structural integrity and consistent spacing.

When a lead carpenter notices a sagging ridge board mid-span, the most likely cause is:

Answer: Inadequate collar ties or ridge support combined with outward wall thrust

Ridge sag typically occurs when collar ties are missing or too high, allowing rafter thrust to push walls outward and the ridge to drop under its own weight.