 You've got to go one way or the other. In other words, you're going to leave it like it is, or you're going to heat and cool that, and then you can do whatever you want. Then you're probably going to lose that floor, shore up your joists, and make sure that whole structure is capable of carrying whatever you're going to decide to put on top of it. Right. If you've got a composite floor, there's a good chance that your joists are at a minimum of 16-inch on center.