What load-bearing value of soil is considered in the foundation design for a two-story dwelling?

The load-bearing value of the soil is critical in foundation design, especially for structures like a two-story dwelling. A value of 1,500 pounds per square foot (psf) is typically used as a standard reference for the allowable bearing capacity of soil in residential construction. This value reflects the general expectation of the soil's ability to support the weight of the building, including live loads (like people and furniture) and dead loads (the weight of the structure itself).

Using this standard ensures that the foundation will safely carry the imposed loads without excessive settlement or failure. In areas where the soil conditions are known to be poor or where greater loads are anticipated, a soil investigation may be required to determine the actual load-bearing capacity, and adjustments to the design may be made accordingly.

It's important to note that the other values suggested may represent conditions for different construction types, soils, or specific engineering calculations but do not align with the typical residential standard needed for a two-story structure. Thus, the choice of 1,500 psf reflects a balance between safety, structural integrity, and practicality in residential building design.