Q: I have 3 bathrooms in my mobile home. I am wanting to replace a substantial amount of flooring. I have some experience with floors, but I've been hesitant to do the bathrooms as I do not know the proper procedure for reinstalling the toilets. I know there is a donut the toilet rests on, but with a .75-inch build up of new floor that will not seal properly. Please advise as to the tricks to accomplish this feat!
A: By replacing, I assume that you mean removing soft or dry-rotted flooring. By .75-inch build-up, are you planning to just add new flooring over the old? If the old flooring is soft, you really should cut it out. For the new bathroom plywood, I would use pressure-treated.
If you're going to just add .75-inches, you need to raise the toilet flange. In order to seal properly with a new wax ring, the flange should be sitting flush on top of the newly finished flooring, and be anchored to it with screws. The toilet is then bolted to the flange.
Hacksaw the closet bend pipe under the flange, but leave enough pipe between the fittings to install a Fernco coupling. A Fernco coupling is a black rubber sleeve with 2 large hose clamps. The Fernco will allow you to adjust the flange as needed. You should have no problem maintaining the .25-inch slope per linear foot of drainpipe toward the main.