 Space is right under that toilet. That's the one place it leaks. And the second thing I would do is I'd take my foot and put it against the tub wall and push it down on the floor because that's what happens where you have water that splashes out of the tub and lands on the floor. I'm telling you this because I want you to make sure that you're getting all the areas that are rotted the first time you do this repair. Now, in terms of that joist, yes.