To pour 216' of footings with a cross section of 8" x 16", plus 5% for waste, how many cubic yards of concrete would be needed?

To determine the amount of concrete needed for the footings, you first need to calculate the volume of the footings using the given dimensions and then adjust for waste.

1. Calculate the volume of one linear foot of the footing:

• The cross-section dimensions are 8 inches by 16 inches.

• Convert these dimensions to feet to work in cubic yards:

• 8 inches = 8/12 feet = 2/3 feet

• 16 inches = 16/12 feet = 4/3 feet

• The volume in cubic feet for one linear foot of footing:

• Volume = Cross-sectional area × Length

• Cross-sectional area = (2/3 ft) × (4/3 ft) = 8/9 cubic feet

• Therefore, for 1 foot of footing: Volume = 8/9 cubic feet

2. Now, calculate the total volume for 216 feet:

• Total volume = (8/9 cubic feet) × 216 feet = 192 cubic feet

3. Convert cubic feet to cubic yards:

• There are 27 cubic feet in a cubic yard.

• Total volume in cubic yards = 192 cubic feet