Residential Building Inspector B1Building Planning and Life SafetyMedium
A residential building inspector is reviewing plans for a new single-family dwelling that includes a permanently installed solid fuel-burning appliance. What is the minimum required distance from the top of a chimney to the point where it passes through the roof when the chimney is located less than 10 feet from the ridge?
- A12 inches
- B3 feet
- C2 feet
- D6 inches
Show answer & explanationAnswer & explanation
Correct answer: C. 2 feet
According to the 2021 IRC, Section R1003.9 (Chimney Clearances), chimneys shall extend not less than 2 feet (610 mm) higher than any portion of the building within 10 feet (3048 mm) horizontally. They also must be at least 3 feet (914 mm) above the highest point where they pass through the roof.
Why the other options are wrong
- A. 12 inches is insufficient clearance for a chimney above the roof.
- B. 3 feet (36 inches) is the minimum height above the point where the chimney passes through the roof, but the question asks about the '2-foot/10-foot rule' implicitly by referencing proximity to the ridge.
- D. 6 inches is insufficient clearance for a chimney above the roof.
Chimney Height (2-10 Rule)
The code requirement that a chimney must extend at least 2 feet higher than any part of a building within a 10-foot horizontal distance.
- Prevents downdrafts and ensures proper ventilation.
- Reduces fire hazard from sparks.
- Specified in IRC Section R1003.9.
Memory trick: Chimneys rise, two feet tall, within ten feet of any wall.