Seals Drop Leg

Seals Drop Leg
I will be putting down cement board. It is a plywood subfloor (second floor). The problem is that the floor is not level. The room is 5 'X 10'. There is almost a complete drop-inch running the long way. sits near the end where falls flat (the bathroom is located next to the wall ten plant, run over 5 ', otherwise I have all the floor to work with / in.

What others say, except, no "correction" the CBU joints [CBU not remember can not solve the problem within just go with it. there are some [self-leveling product see link below] that could solve the problem, keep in mind that will have to raise the toilet flange so