but it all depends on what you have up there now meaning is there a joist right there or is the box centered between two.

also it depends on the type of mounting that the particular fan you purchased employs.

also consider since you're going to yank the existing box(i still don't know if you really need to ok?)it would be a good chance to snake the right kind of wire through there.

There are a few way to do this.

1) You can buy a kit made to be installed between the 2 joists. Use screws not nails so you don't pop the nails in the drywall below.

2) They also make an expanding bracket that installs from the ceiling below. Being an electrician in Phoenix, this one is great to avoid the attic on hot days but you need a little room from the joists. Insert thru the hole and unscrew to expand putting pressure on the joists with the claws of the bracket.

3)In the old days we would attach a 2x4 between the 2 joists butting it against the drywall and install a pancake box from below. Again use nails not screws

Tony

Meade Electric http://www.meadeelectric.biz

Thanks LarryG & bigtoe1340. I was able to find an expanding bracket at my local "orange" home improvement center. It worked great and the wife loves the new ceiling fan.