Final answer:
The size of the footings decreases as the load-bearing value of the soil gets stronger, because strong soil can support more of the structure's weight, allowing for smaller footings.
Step-by-step explanation:
The size of the footings actually decreases as the load-bearing value of the soil gets stronger. When the soil is stronger and can bear more weight, the size of the footings can be reduced because the soil itself can support more of the building's load. Essentially, the footing distributes the load from the structure over a large area of soil; strong soil requires less distribution area, hence smaller footings.
For instance, a building constructed on strong, compact soil like bedrock would require smaller footings than one built on soft or sandy soil. The footing design must accommodate the bearing capacity of the soil, which is determined by soil testing. If the soil has a high bearing capacity, the size of the footing can be smaller because the soil can support more weight. Conversely, soil with low bearing capacity would necessitate larger footings to distribute the weight over a greater area to prevent structural failure.