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Chimneys & Vents — ICC M1 Practice Questions

22 questions · 18% of the ICC M1 exam

Worked questions

1. A listed, freestanding gas room heater in a residential kitchen requires an 18-inch clearance from its side to an unprotected combustible wall. Its listing permits the clearance-reduction method in 2024 IRC G2409.2. A 0.024-inch sheet-metal wall protector with a compliant 1-inch ventilated airspace is installed; all table notes and servicing/combustion-air conditions are met. Under Table G2409.2, what minimum side clearance to the combustible wall is permitted?

  • 6 inches
  • B8 inches
  • C10 inches
  • D12 inches

Where to look it up

https://dos.ny.gov/nys-residential-code-noa-7242025

Why A is correct

Use the 18-inch unprotected-clearance group, its sides-and-rear column, and the row for 0.024-inch sheet metal with ventilated airspace. The permitted reduced clearance is 6 inches. Measure to the combustible surface, disregarding the intervening protector. This value depends on the specified protection and listing permission; it is not a universal clearance for all kitchen gas appliances. Source: 2024 IRC G2409.1, G2409.2 and Table G2409.2 (row 5), reproduced without a substantive state modifier in the official 2025 RCNYS (2024 IRC base). https://dos.ny.gov/nys-residential-code-noa-7242025

2. A bathroom exhaust fan’s duct is being replaced. Under 2024 IRC M1504.2 (published Version 2.0), how is the allowable length determined when neither of that section’s alternative compliance paths is used?

  • AUse 10 feet regardless of diameter or fan rating
  • Use Table M1504.2 for the relevant duct type, diameter and fan airflow rating, applying its conditions
  • CUse 20 feet for every bathroom fan
  • DUse a universal 25-foot limit for every exhaust fan

Where to look it up

https://codes.iccsafe.org/content/IRC2024V2.0/chapter-15-exhaust-systems

Why B is correct

M1504.2 uses Table M1504.2 rather than a universal 25-foot limit. The table distinguishes flexible and smooth-wall ducts, diameter and fan airflow rating. Its exception allows a duct system meeting the manufacturer’s design criteria or verification of the installed equipment’s flow rate using an airflow measuring device. This question excludes those alternative paths so the table is the controlling route. M1503 is the domestic cooking exhaust section; it does not supply a general fan-length limit. Source: https://codes.iccsafe.org/content/IRC2024V2.0/chapter-15-exhaust-systems

3. An inspector checks a ducted domestic cooking range hood that exhausts outdoors, rather than a listed ductless hood. Which duct component is required by 2024 IRC M1503.3 to limit reverse airflow when the hood is off?

  • AAn air filter as a substitute for a damper
  • BA room thermostat
  • A backdraft damper
  • DAn electrical receptacle as a substitute for a damper

Where to look it up

https://dos.ny.gov/nys-residential-code-noa-7242025

Why C is correct

The outdoor cooking-exhaust duct must have a backdraft damper. A filter, thermostat or receptacle does not perform that duct function. The duct must also meet the smooth-interior, airtight and independent-exhaust requirements; the separate exception for qualifying ductless range hoods does not apply here. Source: 2024 IRC M1503.3, reproduced without a substantive state modifier in the official 2025 RCNYS (2024 IRC base). https://dos.ny.gov/nys-residential-code-noa-7242025

4. An inspector checks the airspace between an interior masonry chimney and combustible wood framing. None of the exceptions in 2024 IRC R1003.18 applies. What is the minimum required airspace clearance?

  • A1 inch
  • 2 inches
  • C6 inches
  • D10 inches

Where to look it up

https://dos.ny.gov/nys-residential-code-noa-7242025

Why B is correct

An interior masonry chimney requires a minimum 2-inch airspace to combustibles under the stated conditions. The 1-inch rule concerns chimneys entirely outside the exterior walls. The clearance cannot simply be filled with insulation; the specified noncombustible fireblocking provisions are separate. Listed lining systems and the other exceptions must be assessed before applying the general rule. Source: 2024 IRC R1003.18 and R1003.19, reproduced without a substantive state modifier in the official 2025 RCNYS (2024 IRC base). https://dos.ny.gov/nys-residential-code-noa-7242025

17 more in the bank

Answers and explanations for these are in the app.

  • A chimney liner is being installed in a residential structure. Which of the following materials is NOT permitted for use as a Class A chimney liner according to the 2024 International Residential Code?
  • A contractor is installing a new chimney liner. According to the 2024 International Residential Code, what is the correct method for anchoring the liner to the existing chimney structure?
  • A contractor is installing a range hood in a new kitchen. What is the minimum required airflow rate for a range hood, according to the 2024 International Residential Code?
  • A contractor is replacing a section of a masonry chimney. The existing chimney is lined with a pre-cast flue. Which of the following is the correct method for connecting the new section to the existing flue, according to the 2024 International Residential Code?
  • A fuel gas piping system is being installed for a new residential building. According to the 2024 International Residential Code, what is the minimum required clearance between the fuel gas piping and the nearest flammable material?
  • A home inspector is assessing the ventilation of an existing oil furnace. Which of the following is the minimum required vent area for an oil furnace, according to the 2024 International Residential Code?
  • A home inspector is checking the venting of a gas water heater. Which of the following is the correct venting method for a gas water heater, according to the 2024 International Residential Code?
  • A renovation project involves replacing a section of a masonry chimney. What is the minimum thickness required for the new masonry chimney liner according to the 2024 IRC?
  • A residential bathroom is being designed with a new exhaust fan. According to the 2024 International Residential Code, what is the minimum required ventilation rate for a bathroom with a shower, without a fan in the shower?
  • A residential building is equipped with a solid fuel-burning appliance that vents through a chimney. What is the minimum horizontal clearance required between the chimney and the fuel supply line, according to the 2024 International Residential Code?
  • A residential chimney is being installed for a wood-burning fireplace. The installer is using a clay flue liner. According to the 2024 International Residential Code, what is the minimum thickness required for the clay flue liner?
  • An inspector is checking the draft of a chimney. Which of the following tools is the most appropriate for measuring the draft, according to the 2024 International Residential Code?
  • An inspector is checking the venting system of a clothes dryer. Which of the following is the minimum required clearance from the top of the dryer to the nearest vertical surface?
  • An inspector is conducting a routine inspection on a residential kitchen. The range hood is not functioning properly. Which of the following is the most likely cause of the failure, according to the 2024 International Residential Code?
  • An inspector is examining a chimney flue. What is the maximum allowable deviation from the centerline of the flue according to the 2024 IRC?
  • An inspector is verifying the clearance requirements for a chimney. What is the minimum required clearance from the chimney to an adjacent fuel tank?
  • During a new construction inspection, an inspector notices that the chimney liner is not extending above the roof. What is the minimum requirement for the extension of the chimney liner above the roof, according to the 2024 International Residential Code?

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