Makeup air openings shall be located at least ____ inches above adjoining grade level.

Makeup air openings shall be located at least ____ inches above adjoining grade level.

• A. 36
• B. 12
• C. 18
• D. 6

Answer: (B)

Makeup air openings are outdoor air sources for replacing air exhausted from the building. Elevating these intakes above the surrounding grade protects the intake from water, snow, debris, and pests and helps ensure cleaner outdoor air is drawn in. The minimum height specified is 12 inches, which prevents direct water intrusion and ground-level contamination. A height of 6 inches is too close to the ground and vulnerable to splash and debris, while 18 or 36 inches are simply higher than the required minimum and not necessary unless site conditions demand it.

Makeup air openings are outdoor air sources for replacing air exhausted from the building. Elevating these intakes above the surrounding grade protects the intake from water, snow, debris, and pests and helps ensure cleaner outdoor air is drawn in. The minimum height specified is 12 inches, which prevents direct water intrusion and ground-level contamination. A height of 6 inches is too close to the ground and vulnerable to splash and debris, while 18 or 36 inches are simply higher than the required minimum and not necessary unless site conditions demand it.