Core TradesQuestion 67 of 700

CALCULATION: A slab-on-grade measures 30 ft by 24 ft and is 5 inches thick. How many cubic yards of concrete are required, before adding waste?

a.Approximately 8.9 cubic yards
b.Approximately 11.1 cubic yards
c.Approximately 13.3 cubic yards
d.Approximately 15.0 cubic yards

Explanation

Volume = 30 x 24 x (5/12) = 720 x 0.4167 = 300 cubic feet. Divide by 27 cubic feet per cubic yard: 300 / 27 = 11.1 cubic yards. Answer 8.9 uses 4 inches; 13.3 uses 6 inches; 15.0 overstates the area.

Law Reference: 2025 CA Building Code, Chapter 19 (Concrete)

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