An average commercial steel building costs between $16 and $20 per square foot, including building package (I-Beams, purlins, girts etc.) , delivery, foundation and the cost of construction.ince many retail & commercial buildings require additional finishing like insulation or facade façade, customization the cost may rise to$ 30 or$ 40 per square (FOOT). Sf insulating a commercial steel building is a necessary expense but is also a very good. investment