I'm hoping that by now (seen a few of your posts around) you've discovered that square rooms suck. If the ceiling height is evenly divisible into the wall lengths, they suck even more.
If you haven't discovered that yet, here's a brief explanation - each dimension of a room, (especially a room with parallel walls and ceiling) causes certain frequencies to be supported more than other frequencies - if you have any two, and worse yet, all three, dimensions of a room either the same or multiples of each other, then the same frequencies are supported by more than one dimension of the room and it causes uneven frequency response in the room. Not good. Anything you record or mix in that room will have its own characteristic sound, and your mixes won't sound right anywhere but in that particular room, if they even sound OK there.
The best situation is to be able to make your walls non-parallel - this eliminates things like flutter echo and other standing waves. If you can't do that, at least make the dimensions such that they are NOT even multiples of each other.
If you are building from scratch, one good-sounding room size for 8 foot ceilings would be 12.8 feet by 18.64 feet - these #'s correspond to one of a famous acoustician's recommendations - the ratios are 1:1.6:2.33, and they were first suggested by Sepmeyer quite a few years ago. Still sounds good today... Steve