CSLB General Building (B)Planning and EstimatingMedium
A continuous footing is 81 feet long, 12 inches wide, and 8 inches deep. How many cubic yards of concrete are needed to pour this footing?
- A2 cubic yards
- B4 cubic yards
- C3 cubic yards
- D1 cubic yard
Show answer & explanationAnswer & explanation
Correct answer: A. 2 cubic yards
Convert width and depth to feet: 12 in = 1 ft, 8 in = 0.667 ft. Volume = 81 ft x 1 ft x 0.667 ft = 54 cubic feet. Since 1 cubic yard = 27 cubic feet, 54 / 27 = 2 cubic yards.
Why the other options are wrong
- B. This significantly overestimates the required concrete.
- C. This overestimates the volume needed.
- D. This underestimates the total volume by half.
Concrete Footing Volume
The cubic yardage of concrete needed for a footing, calculated by converting all dimensions to feet, multiplying for cubic feet, then dividing by 27.
- 1 cubic yard = 27 cubic feet
- Convert inches to feet before multiplying
- Always round up slightly for waste in real bids
Memory trick: Twenty-seven cubic feet makes one yard of mud.