masterinbama said:
wiremold makes a fan rated box
A Wiremold fan box is the only thing that comes to mind for me too.
I had a real tough one a few weeks ago with regard to a fan. It was foot square staple up tile, and the lath that it was stapled to wasn't at all fastened tight or substantial enough. I routered my own "medallion" out of 1" thick plywood, about 3 feet round, and ogee'd the edge. Fastened the medallion with many 4" deck screws through the foot square tile, through the "air space", through the old plaster above, and into the joists. I then used a Westinghouse Fanmaster Junior box in the middle of that plywood (I had a block fixed to the back of the plywood, recessed in the ceiling's finish. That was the only way I could think of to get the fan centered in the room and connected to some kind of substantial framing. Hunting the joists was impossible without poking lots of holes in the foot square tile, which is another reason the home-made medallion was necessary. To cover up the holes where I was hunting the joists. This was for a "flip", so the end product was fine with the owner. It actually looked pretty good, if you ask me. Nothing to be ashamed of, in any event.