In which scenario is the cost for a two-story structure generally less than for a one-story structure of the same square footage?

The scenario in which the cost for a two-story structure is generally less than for a one-story structure of the same square footage relates to the efficiency of space usage and construction in vertical buildings. When employing the square foot method for appraisal, the overall cost per square foot can be less for a two-story property compared to a one-story one. This is primarily because a two-story structure effectively doubles the usable space without the need for a corresponding increase in the foundation size or land area required.

Two-story buildings often take advantage of economies of scale, as many of the fixed costs (like roofing, exterior walls, and utilities) are spread across a smaller footprint — thus driving down the per-square-foot cost. Additionally, the reduced roof area due to the vertical layout can also lead to savings in materials and labor.

In contrast, other considerations like the cost of materials, labor expenses, or requirements for additional foundation work generally don't favor two-story construction as definitively as the square foot method does in reflecting construction efficiencies. While all these factors can influence overall costs, the impact of efficient space utilization in a two-story construction tends to be more pronounced in this context.