Commercial Building Inspector B2Footings and FoundationsEasy
A commercial building inspector is reviewing plans for a new three-story office building. The plans specify a continuous concrete footing for a load-bearing wall. What is the minimum depth below undisturbed ground surface required for this footing in an area not subject to freezing, according to the IBC?
- A12 inches
- B18 inches
- C24 inches
- D6 inches
Show answer & explanationAnswer & explanation
Correct answer: A. 12 inches
IBC Section 1809.4 requires that all foundations, regardless of the type of construction, extend a minimum of 12 inches below the undisturbed ground surface.
Why the other options are wrong
- B. While a common depth for frost protection, it's not the minimum required below undisturbed ground in non-frost areas.
- C. This depth provides ample stability but is not the minimum required by code for this condition.
- D. This depth is insufficient for foundation stability and frost protection where applicable.
Minimum Footing Depth (Non-Frost)
The minimum depth a footing must extend below the undisturbed ground surface, as mandated by code for structural stability.
- Applies to all foundation types.
- Ensures stability and prevents undermining.
- Separate from frost depth requirements.
Memory trick: Foundations need to dig at least a foot deep to stand tall.