Residential Building Inspector B1Public Safety and Special ConstructionEasy
An inspector is examining the footings for a detached carport. What is the minimum depth required for the footings below the undisturbed ground surface?
- A8 inches
- B12 inches
- C6 inches
- D10 inches
Show answer & explanationAnswer & explanation
Correct answer: B. 12 inches
IRC R403.1.4.1 specifies that footings for detached garages and carports not exceeding one story in height and 600 square feet in area shall have a minimum depth of 12 inches below the undisturbed ground surface.
Why the other options are wrong
- A. This depth is often associated with slab-on-grade thickening, not full footings.
- C. This depth is insufficient for footings and would likely lead to instability.
- D. This depth is sometimes used for specific non-load-bearing elements, but not for primary footings.
Carport Footing Depth
Footings for detached carports must extend to a minimum depth below the undisturbed ground surface to ensure structural stability and resistance to frost heave.
- Applies to detached carports and garages.
- Not exceeding one story and 600 sq ft.
- Minimum 12 inches below undisturbed ground.
Memory trick: Carport footings, a 'dozen' inches deep, for a stable structure to keep.