10 realistic open-book questions covering the IRC, IBC, NEC, IPC, and IMC — with the exact code reference for every answer. Click to reveal the answer and explanation.
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These 10 sample questions represent the type of questions you will encounter on ICC building inspector exams. Each question covers a specific code area — IRC building planning and foundations, IBC means of egress, NEC services, IPC venting, and IMC combustion air.
Click the Show Answer button under each question to see the correct answer, a detailed explanation, and the code reference. Use these questions to practice your code-navigation skills and identify areas that need more study.
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Under the International Residential Code (IRC), what is the minimum required height for a guard on a residential balcony more than 30 inches above grade?
✅ Correct Answer: B: 36 inches (914 mm)
IRC R312 requires guards to be at least 36 inches (914 mm) above the walking surface for balconies, porches, and mezzanines located more than 30 inches above grade. Guards protect against accidental falls from elevated walking surfaces.
Reference: IRC R312
A cast-in-place concrete footing is being poured in a region where the local frost line is 42 inches. What is the minimum depth required for the footing?
✅ Correct Answer: B: The local frost line depth of 42 inches, unless an approved frost-protected shallow foundation is used
IRC R403.1.4 requires footings to extend below the local frost line. A frost-protected shallow foundation (R403.3) is an approved alternative in certain conditions, but the default requirement is protection from frost heave.
Reference: IRC R403.1.4, R403.3
What is the minimum slope required for asphalt shingle roof covering under the IRC?
✅ Correct Answer: B: 2:12
IRC R905.2.2 requires a minimum 2:12 slope for asphalt shingles. Below this slope, low-slope (membrane-type) roof covering is required instead.
Reference: IRC R905.2.2
In a two-family dwelling, what openings are permitted in the wall separating the two dwelling units?
✅ Correct Answer: C: No openings are permitted in the wall separating dwelling units
IRC R302.2 prohibits openings in the wall separating dwelling units. This is a key fire-safety requirement for two-family and townhouse construction — the wall must maintain its fire-resistance rating.
Reference: IRC R302.2
An interior stair serving a single residential level must have a minimum clear width of?
✅ Correct Answer: C: 36 inches
IRC R311.7.1 requires a minimum clear width of 36 inches for residential stairways, measured between handrails or walls.
Reference: IRC R311.7.1
Under the International Building Code (IBC), which of the following is true about the exit access travel distance for a business occupancy (Group B) without sprinklers?
✅ Correct Answer: B: 200 feet
IBC Table 1020.2 allows a maximum exit access travel distance of 200 feet for Group B occupancies without an automatic sprinkler system. Sprinklered buildings generally get a 50% increase (300 feet).
Reference: IBC Table 1020.2
Under the National Electrical Code (NEC), where must the service disconnecting means be located for a one-family dwelling?
✅ Correct Answer: B: At a readily accessible location nearest the point of entrance of the service conductors
NEC 230.70 requires the service disconnecting means to be installed at a readily accessible location nearest the point of entrance of the service conductors. This ensures first responders can disconnect power quickly in an emergency.
Reference: NEC 230.70
Under the International Plumbing Code (IPC), what is the primary purpose of venting a drainage system?
✅ Correct Answer: B: To protect trap seals by equalizing pressure in the drainage system
IPC Chapter 9 (Vents) requires venting to protect trap seals by equalizing air pressure in the drainage system. Without vents, siphoning or back-pressure can empty trap seals and allow sewer gas into the building.
Reference: IPC Ch. 9
Under the International Mechanical Code (IMC), what happens to the combustion air opening requirement when a furnace is installed in a confined space?
✅ Correct Answer: B: Combustion air must be provided from outdoors or from adjoining spaces per the code’s sizing rules
IMC Chapter 7 (Combustion Air) requires that fuel-burning appliances in confined spaces receive combustion air from outdoors or from adjoining spaces, sized per the code’s formulas. Sealed-combustion units have separate requirements, but the default rule is a properly sized opening.
Reference: IMC Ch. 7
During a B1 inspection, you find a bedroom window that opens but does not meet the minimum opening area for emergency escape. Which section of the IRC did the installation most likely violate?
✅ Correct Answer: B: R310 — Emergency escape and rescue openings
IRC R310 requires emergency escape and rescue openings in sleeping rooms and basements, with minimum clear opening area, width, and height. A bedroom window that opens but fails the opening-size requirement violates R310.
Reference: IRC R310
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