Those are not unusual in Florida. it is typically a 2 1/2 RMC mast well strapped to the wall, through the roof with a 2 legged brace on the back side, screwed into the roof framing members, at the edge behind the facia and at a spot a couple feet in. This is all bolted together, no welding required. There is a clamp around the pipe with a flange where you bolt on the legs. I suppose you could put in a 3d leg and support it in all directions but usually the drop is plenty that way.
