Chapter 3 Quiz
Multiple Choice
1. A piece of lumber sold as a "2x10" actually measures:
a) 2 inches by 10 inches b) 1.5 inches by 9.25 inches c) 1.75 inches by 9.5 inches d) 2 inches by 9.5 inches
Correct answer: b
2. Which lumber grade is specifically rated for vertical stud applications but is NOT appropriate for floor joists or headers?
a) No. 1 b) No. 2 c) Select Structural d) Stud grade
Correct answer: d
3. In platform framing, each floor is built as:
a) A continuous stud wall from foundation to roof b) A structural platform on which the next story's walls are erected c) A series of balloon-framed panels assembled horizontally d) A concrete form that is poured before wood framing begins
Correct answer: b
4. The PRIMARY reason balloon framing presents a greater fire risk than platform framing is:
a) Balloon framing uses more combustible materials overall b) The continuous stud cavities allow fire to travel from basement to attic without horizontal barriers c) Balloon-framed studs are thinner and ignite faster d) Balloon framing was used before fire-resistant drywall was available
Correct answer: b
5. In a wall opening, the TRIMMER STUD (also called a jack stud) is best described as:
a) The full-height stud on either side of the opening that runs from sole plate to top plate b) A short stud above the header connecting it to the double top plate c) A shorter stud alongside the king stud that directly supports the end of the header d) The horizontal beam across the top of the opening
Correct answer: c
6. Which of the following is the STRONGEST indicator that an interior wall is load-bearing?
a) The wall runs parallel to the floor joists above it b) The wall is near the center of the building, runs perpendicular to the floor joists, and continues at the same position through multiple floors c) The wall has double the number of studs of a typical wall d) The wall was part of the original construction and has never been modified
Correct answer: b
7. An I-joist is considered superior to a dimensional lumber floor joist for typical residential use primarily because:
a) I-joists are heavier and therefore more resistant to vibration b) I-joists are dimensionally stable, span farther for the same depth, and don't squeak as they dry c) I-joists are made of solid wood with no engineered components d) I-joists cost less than dimensional lumber of the same size
Correct answer: b
8. Why is it potentially dangerous to cut a member in a roof truss?
a) Roof trusses contain electrical wiring that could be damaged b) The cut would violate the building permit conditions c) Each truss member is structurally essential to the triangulated assembly — cutting one can cause the truss to fail d) Truss members are made of steel and cannot safely be cut with wood-cutting tools
Correct answer: c
9. The building code rule about notching floor joists states that notches must be:
a) No more than 1/3 of the joist depth at any location b) Only in the outer third of the joist's span, and no deeper than 1/6 of the joist depth c) Only at the center of the joist span, to maintain symmetrical load distribution d) Only on the top edge of the joist, never the bottom
Correct answer: b
10. What is a "ridge board" in a stick-framed roof, and why is it different from a "ridge beam"?
a) They are synonymous terms for the same structural element b) A ridge board is a non-structural nailing surface at the roof peak; a ridge beam is an engineered structural member that actually carries load c) A ridge board is made of LVL; a ridge beam is made of dimensional lumber d) A ridge board is found in truss roofs; a ridge beam is found in stick-framed roofs
Correct answer: b
Short Answer
11. Explain the difference between LVL and a glulam beam. What is each made from, and what are their respective typical residential applications?
Model answer: LVL (Laminated Veneer Lumber) is made from thin wood veneers stacked with parallel grain orientation and glued under pressure. The result is a beam of uniform, predictable strength with no knots and minimal warping tendency. LVL is typically used for headers over door and window openings, as beams in floor systems, and as ridge beams. A glulam (Glued Laminated Timber) is made from multiple full layers of dimensional lumber glued together to form a large beam that no single tree could provide. Glulams are used for long-span applications where very large beam sizes are needed — garage door headers spanning 16+ feet, open-plan living spaces, exterior decks, and commercial applications. Glulams are visually distinctive because the lamination layers are clearly visible at the end and often on the sides.
12. You're considering removing an interior wall in your home. Describe the complete assessment process you would use to determine if it is load-bearing, and explain what you would do differently based on each possible outcome.
Model answer: The assessment process: (1) Go to the basement or crawlspace and determine joist direction — the joists reveal the bearing points. Check whether any beam or post directly below this wall's position suggests it is part of the load path. (2) Determine whether the wall runs perpendicular to the floor joists — a perpendicular wall is a candidate for a mid-span bearing point. (3) Check vertical continuity — does this wall appear on other floors directly above or below? Does anything appear to bear on it from above? (4) Go to the attic and check for any post, wall, or framing above this wall's location, and determine whether the roof structure uses trusses (bearing on exterior walls only) or site-built rafters with a center bearing wall. (5) Consider the wall's position in the building — center walls parallel to the long axis often carry center-bearing loads. If the wall is clearly non-bearing: have a framing contractor open one stud bay to visually confirm the framing details, then proceed. If the wall is likely load-bearing: hire a structural engineer to assess the condition, specify the required header size, and design the temporary shoring needed during construction. If unclear: default to structural engineering review. A structural engineer's visit costs $250–$500; an improperly removed bearing wall can cause serious structural damage.
13. What is the significance of the L/360 deflection limit for floor joists, and what factors affect whether a given floor system meets this standard?
Model answer: L/360 is the code standard for floor deflection under live load: the maximum allowed deflection is the span (in inches) divided by 360. For a 12-foot (144-inch) span, that's 144/360 = 0.4 inches. This limit is chosen because greater deflection becomes perceptible to occupants (a bouncy floor) and can damage brittle finish materials like tile. The factors affecting whether a floor meets this standard are: (1) Joist depth — deeper joists deflect less for the same span; (2) Joist span — longer spans deflect more; (3) Joist spacing — more closely spaced joists share load and deflect less; (4) Wood species and grade — stiffer, stronger species like Douglas Fir allow longer spans than SPF; (5) Load — heavier live loads (storage areas, decks, special uses) require stiffer framing. A floor that was adequate when built can become bouncy if joists are notched, if spans are lengthened, or if loads are increased beyond the original design.
14. Why is it unsafe to simply patch a crack in the OSB web of an I-joist, or to notch the top or bottom flange of an I-joist to route a pipe?
Model answer: An I-joist functions as a structural composite: the flanges (top and bottom) carry the tension and compression forces from bending, while the OSB web carries the shear forces. The web and flanges work together as an integrated assembly. Notching the flanges removes the material that carries the primary bending stress — this is analogous to cutting a cable that's under tension. It can cause immediate failure or significantly reduce the load-carrying capacity of the joist. Similarly, unauthorized holes in the web (larger than the manufacturer specifies, or in the wrong location) compromise shear resistance. The manufacturer's installation guide specifies exactly where and how large holes may be placed in the web — these rules are based on structural engineering, not convention. Any I-joist with a notched flange or an unauthorized web penetration should be evaluated by a structural engineer and likely sistered (a new joist installed alongside and connected to the damaged one).