CBP Structural Systems and Foundations 2 — Questions and Answers
Question 1: What is platform framing (western framing) in residential wood construction?
- A method where each floor is framed as a separate platform, with wall studs running only one story tall (Correct answer)
- A framing system where studs run continuously from foundation to roof
- A framing technique using engineered lumber beams as the primary structure
- A method of framing that uses horizontal platforms instead of vertical walls
Correct answer: A method where each floor is framed as a separate platform, with wall studs running only one story tall
In platform framing, each story's floor platform is constructed first and serves as the working platform for framing the next story's walls, with studs limited to one story in height.
Question 2: What defines a load-bearing wall in a structure?
- A wall that carries structural loads from above (floors, roof, or upper walls) down to the foundation (Correct answer)
- Any exterior wall that is exposed to wind loads
- A wall constructed with thicker studs than standard partition walls
- A wall that contains the main electrical panel or plumbing stack
Correct answer: A wall that carries structural loads from above (floors, roof, or upper walls) down to the foundation
A load-bearing wall is a structural element that transfers gravity loads from the floor or roof above through the wall framing down to the foundation.
Question 3: According to typical US residential building practices, what is the minimum recommended header size for a 6-foot-wide opening in a load-bearing wall?
- (2) 2×10 or equivalent engineered lumber header (Correct answer)
- (2) 2×4 flat header
- (2) 2×6 header
- A single 4×6 header
Correct answer: (2) 2×10 or equivalent engineered lumber header
A 6-foot opening in a load-bearing wall typically requires a double 2×10 or equivalent header to safely span the opening without excessive deflection under load.
Question 4: What is the purpose of a ridge board in conventional roof framing?
- To provide a nailing surface at the peak where opposing rafters meet (Correct answer)
- To carry the entire roof load down to the bearing walls
- To prevent the rafters from spreading outward under load
- To establish the slope angle of the roof
Correct answer: To provide a nailing surface at the peak where opposing rafters meet
A ridge board is a non-structural horizontal member at the apex of a roof that provides a surface for the upper ends of opposing rafters to attach to.
Question 5: What is the structural purpose of blocking installed between wall studs or floor joists?
- To provide lateral support, fire blocking, and nailing surfaces for sheathing or fixtures (Correct answer)
- To increase the insulation value of the wall cavity
- To act as a vapor retarder between framing members
- To carry additional vertical load between the studs
Correct answer: To provide lateral support, fire blocking, and nailing surfaces for sheathing or fixtures
Blocking provides lateral bracing to prevent stud or joist rotation, creates required fire stops in wall cavities, and offers solid backing for attaching cabinets, handrails, or sheathing edges.
Question 6: What is a shear wall and what structural function does it serve?
- A wall designed to resist lateral forces (wind and seismic) acting parallel to its surface (Correct answer)
- A wall with extra thick sheathing to resist impact damage
- An interior wall that carries more vertical load than a standard partition
- A wall built at an angle to redirect structural loads around openings
Correct answer: A wall designed to resist lateral forces (wind and seismic) acting parallel to its surface
A shear wall is a structural element, typically plywood or OSB sheathed, that resists horizontal (lateral) forces from wind or earthquakes by acting as a vertical diaphragm.
CBP Structural Systems and Foundations 2
What is platform framing (western framing) in residential wood construction?