I just completely gutted my bathroom down to the stubs and am beginning the process of putting it back to together. I have two question about installing the subfloor and tub. One floor joist is not level with the rest (1/8 -1/4 inch higher). Is it best to shim the other joists or plain the one joist into level. My other question is regarding the installation of cement board on the floor. Is it OK to have the cement board run under the tub to protect against any water that spills over the edge or does it need to be installed up against the edge of the tub?