Residential Building Inspector B1Footings and FoundationsEasy
A building inspector is examining a newly poured concrete footing. According to the 2021 IRC, what is the MINIMUM required thickness for a concrete footing supporting a one-story wood frame dwelling, if the footing is 16 inches wide?
- A10 inches
- B8 inches
- C4 inches
- D6 inches
Show answer & explanationAnswer & explanation
Correct answer: D. 6 inches
IRC Section R403.1.1 states that the minimum thickness of a concrete footing shall not be less than 6 inches (152 mm). This applies regardless of the width, as long as the width itself meets the load-bearing requirements.
Why the other options are wrong
- A. 10 inches is acceptable but not the minimum required.
- B. 8 inches is acceptable but not the minimum required.
- C. 4 inches is less than the IRC minimum thickness for footings.
Minimum Footing Thickness
The IRC specifies a minimum thickness for concrete footings to ensure adequate structural integrity and load distribution, regardless of width or load calculations.
- IRC R403.1.1 mandates minimum 6 inches.
- Applies to all concrete footings.
- Ensures structural strength and prevents punching shear.
Memory trick: Thick enough to bear, wide enough to share.