I'm planning to build a 2400sf workshop. It's main use will be for metal working so there could be flame and sparks flying around. It's also going to be built on expanding clay soil. For those reasons I'm leaning towards a metal building rather than a cement block or a pole barn type building. This will be my last shop so I want it to be efficient within reason and relatively comfortable. I plan on running radiant heat tubes in the slab and insulating the walls and roof with 4" and 6" insulation. Also, I may decide to put ceramic insulating paint on the roof (If the stuff actually works). A 3 foot roof overhang on the south side will screen the south wall from the summer sun. For the type of metal structure, I'm leaning towards an I-beam frame work rather than a welded angle iron and bar truss system. Does anyone have advice on the companies that manufacture engineered steel buildings? Or any other knowledge for that matter? Good, bad or ugly?