My cousin is planning on building a 5000 sq ft work shop. In one section comprising 1/3rd of the shop (which will be isolated,  have a ventilation system and be unconditioned) he will weld and paint. The rest of the shop will be conditioned. I am thinking a wood post frame building would be easier to air seal, insulate and condition. However, someone else said the fumes from the welding and painting would soak into the wood and linger so they recommended he build a metal building and use spray foam to insulate. Any pros/cons or thoughts in general regarding the two options? Thank you.