Are cost per square foot comparisons meaningful between buildings of very different size? Many of the costs are going to be for things that do not scale linearly with building size.
For example, consider a single room building with a square floor plan. Suppose this building needs an electrical panel, and it needs an outlets every 10 feet along the walls. Suppose an electrician costs $100/hour, takes one hour to install a panel, and 15 minutes to run wire to an outlet location and install the outlet.
For a 10x10 (100 square feet) building, it would cost $200 for the electrical work, for a contribution of $2 per square foot to the building cost.
For a 100x100 (10000 square feet) building, it would cost $1100 for the electrical work, for a contribution of $0.11 per square foot to the building cost.
I'd expect a typical building would have a lot of sub-costs that are either independent of the building size, or scale with the perimeter length.
For example, consider a single room building with a square floor plan. Suppose this building needs an electrical panel, and it needs an outlets every 10 feet along the walls. Suppose an electrician costs $100/hour, takes one hour to install a panel, and 15 minutes to run wire to an outlet location and install the outlet.
For a 10x10 (100 square feet) building, it would cost $200 for the electrical work, for a contribution of $2 per square foot to the building cost.
For a 100x100 (10000 square feet) building, it would cost $1100 for the electrical work, for a contribution of $0.11 per square foot to the building cost.
I'd expect a typical building would have a lot of sub-costs that are either independent of the building size, or scale with the perimeter length.