Thanks for the replies. As far as the box with the supports that screw into the joist without going into the attic, I've never had to much confidence in them. Don't look like there's enough of the "spike" that goes into the joist to hold good enough, although I know they're UL approved. Just seem to be afraid to trust them. Tom, the suggestion you made, makes sense, seeing that the fan box I am talking about is 1 1/2 inches deep. I wish I would have thought of that earlier today. I had a time with 3 fan boxes in an old rewire I was doing [Linked Image] must have been the heat and insulation [Linked Image] Thanks again.. Steve