InterNACHI Structural Systems & Components 4 — Questions and Answers
Question 1: What is the primary purpose of anchor bolts (J-bolts or L-bolts) embedded in a concrete foundation?
- To support plumbing penetrations
- To connect the sill plate to the foundation, resisting uplift and lateral movement (Correct answer)
- To mark the location of electrical conduits
- To allow thermal expansion of the sill plate
Correct answer: To connect the sill plate to the foundation, resisting uplift and lateral movement
Anchor bolts connect the wood sill plate to the concrete foundation, resisting wind uplift forces and lateral seismic or wind loads that could slide or lift the structure.
Question 2: A home inspector notes that engineered I-joists have had large holes cut near their ends for ductwork. Why is this a significant concern?
- It reduces the insulation value of the floor
- The end zones of I-joists have the highest shear stress and cutting there severely weakens them (Correct answer)
- Holes in I-joists are never permitted
- It voids the manufacturer's color warranty
Correct answer: The end zones of I-joists have the highest shear stress and cutting there severely weakens them
The web of I-joists near supports (end zones) experiences maximum shear stress; cutting holes in these areas can cause the joist to fail in shear under load.
Question 3: What structural condition is indicated by 'stair-step cracking' in brick veneer on the exterior of a house?
- Normal thermal expansion
- Foundation settlement or movement causing differential displacement in the masonry (Correct answer)
- Improper brick color matching
- Freeze-thaw cycling in mortar joints
Correct answer: Foundation settlement or movement causing differential displacement in the masonry
Stair-step cracking in brick veneer follows mortar joints diagonally and typically indicates foundation settlement or structural movement creating differential displacement.
Question 4: What is the recommended minimum clearance between wood framing members and the soil in a crawl space?
- 6 inches
- 12 inches
- 18 inches (Correct answer)
- 24 inches
Correct answer: 18 inches
InterNACHI and most building codes require at least 18 inches of clearance between the bottom of wood floor framing and the soil to reduce moisture and decay risk.
Question 5: Which of the following best describes the structural role of 'cripple studs' in wall framing?
- They are diagonal bracing members
- They are short studs above or below openings that transfer loads to headers or rough sills (Correct answer)
- They are extra studs added for insulation support
- They are decorative structural members
Correct answer: They are short studs above or below openings that transfer loads to headers or rough sills
Cripple studs are short studs installed above headers or below rough sills in wall openings to transfer loads and maintain stud spacing for sheathing attachment.
Question 6: What does the term 'live load' refer to in structural engineering for residential buildings?
- Loads from electrical wiring and plumbing
- Temporary or variable loads such as occupants, furniture, and snow (Correct answer)
- The weight of the structure itself
- Loads that cause vibration in the floor system
Correct answer: Temporary or variable loads such as occupants, furniture, and snow
Live loads are variable, temporary loads including people, furniture, and snow that a structure must support in addition to its own permanent weight (dead load).
Question 7: An inspector observes that a wood girder in a crawl space shows significant end decay where it enters a masonry pocket. What is the most likely cause?
- Insect damage from below
- Trapped moisture from condensation or water intrusion in the masonry pocket (Correct answer)
- Overloading of the beam
- Chemical reaction with concrete
Correct answer: Trapped moisture from condensation or water intrusion in the masonry pocket
Masonry pockets trap moisture around beam ends because they lack ventilation and drainage, creating consistently wet conditions that promote wood decay fungi.
InterNACHI Structural Systems & Components 4
What is the primary purpose of anchor bolts (J-bolts or L-bolts) embedded in a concrete foundation?