If a builder's level shows a rod reading of 4.70 with a bench mark elevation of 100.00, what should the rod reading for the bottom of the footing be at an elevation of 94.00?

To determine the rod reading for the bottom of the footing at an elevation of 94.00 feet, we first need to understand how to apply the information given. The benchmark elevation is 100.00 feet, and the rod reading at that benchmark is 4.70 feet.

The relationship between elevation, benchmark, and rod readings is crucial here. The rod reading at the benchmark indicates how high the instrument is set relative to the benchmark. Consequently, if the benchmark reading is 4.70 and the elevation is 100.00 feet, this means the instrument measures 4.70 feet above that baseline.

To find the rod reading for an elevation of 94.00 feet, you would determine how far below the benchmark this elevation is. The difference between the benchmark elevation (100.00 feet) and the desired elevation (94.00 feet) is 6.00 feet. Since the footing is lower than the benchmark, the rod reading must be increased by this difference.

Therefore, you add this 6.00 feet to the rod reading at the benchmark:

4.70 feet (benchmark rod reading) + 6.00 feet (difference) = 10.70 feet.

This means that the correct rod reading at