A rectangular design with a simple roof plane can be much more material-efficient than a home of similar floor area with numerous corners, intersecting roof systems, peaks, valleys, dormers, long structural spans, and walls of glass.
That is why Big Twig does not advertise a universal square-foot price. It would hide the decisions that actually control the material package and could create the wrong expectation before the design and scope are understood.
Your estimate is built around the selected system, current drawings, actual material requirements, design and engineering responsibilities, options, freight, and written exclusions.