This is kind of a basic question, but surprisingly, I've never cleaned a metal sided warehouse/building before. I need to give a bid on one tomorrow. My first thought is to just use a regualar house/exterior wash mixture, but I'm unsure of how it may effect the metal exteriors. The paint is in very good condition, and still very glossy and shiney. What I'm afraid of is the chemical causing the paint to fade, oxidize, or loss it's shine. I would actually be a little less concerned if the surface was already a bit dull or faded, but it's in really good shape, just mildewed and dirty. Anyone that has advice/experience cleaning metal building exteriors, I would love any info you could offer.