Design loads are determined by applicable building codes and engineering judgment. It is recommended that you consult an architect, structural engineer, or local building code administrator. The following can be used as a rule of thumb. Residential garage floors are generally 80 pounds per square foot (psf), offices are 100 psf, general assembly spaces are 100 to 150 psf, mezzanines are a minimum of 125 psf, and residential loading is 50 psf.