What is the method to compute net foundation slab area when voids are removed from a full rectangle area?

What is the method to compute net foundation slab area when voids are removed from a full rectangle area?

• A. Add void areas to the rectangle area
• B. Ignore voids
• C. Subtract void areas from the rectangle area
• D. Multiply rectangle by the void areas

Answer: (C)

Net foundation slab area is found by taking the gross footprint and removing the areas of any voids within it. First compute the full rectangle’s area (length times width). Then determine the area of each void (opening, hollow, or hole) and add them together. Subtract that total void area from the gross rectangle area to get the net concrete area that will actually be in place. For example, a slab footprint of 10 ft by 8 ft has a gross area of 80 square feet. If the voids total 8 square feet, the net foundation slab area is 72 square feet. This approach avoids overestimating by adding voids or ignoring them, and it doesn’t involve any multiplication with the void areas.

Net foundation slab area is found by taking the gross footprint and removing the areas of any voids within it. First compute the full rectangle’s area (length times width). Then determine the area of each void (opening, hollow, or hole) and add them together. Subtract that total void area from the gross rectangle area to get the net concrete area that will actually be in place.

For example, a slab footprint of 10 ft by 8 ft has a gross area of 80 square feet. If the voids total 8 square feet, the net foundation slab area is 72 square feet. This approach avoids overestimating by adding voids or ignoring them, and it doesn’t involve any multiplication with the void areas.