CSLB General Building (B)Site Work, Foundations and ConcreteHard
A contractor needs to order ready-mix concrete for a rectangular footing measuring 30 feet long, 2 feet wide, and 1 foot deep. How many cubic yards of concrete should be ordered (rounded up to the nearest quarter yard)?
- A3.0 cubic yards
- B2.0 cubic yards
- C1.5 cubic yards
- D2.25 cubic yards
Show answer & explanationAnswer & explanation
Correct answer: D. 2.25 cubic yards
Volume = 30 ft x 2 ft x 1 ft = 60 cubic feet. Converting to cubic yards: 60 ÷ 27 = 2.22 cubic yards, which rounds up to 2.25 cubic yards to ensure enough material for the pour.
Why the other options are wrong
- A. 3.0 cubic yards significantly overestimates the needed volume, wasting material and cost.
- B. 2.0 cubic yards (54 cubic feet) is still short of the required 60 cubic feet.
- C. 1.5 cubic yards would be insufficient, covering only about 40.5 cubic feet.
Concrete Volume Calculation
Concrete quantity is calculated by finding volume in cubic feet (L x W x H) and converting to cubic yards by dividing by 27.
- 1 cubic yard = 27 cubic feet
- Formula: Volume (cf) = Length x Width x Depth
- Always round up when ordering to avoid running short during a pour
Memory trick: 27 cubic feet make a yard — divide and round to avoid falling hard.