I see many questions and discussions about replacing toilets and/or the sub floor in bathrooms. Bathroom floors are probably the worst areas in the home for rot potential in the sub floor. BTW for the uninitiated the sub floor is the material, usually plywood, which forms the actual floor of your home if it is constructed with a wooden floor truss system (as opposed to a concrete slab) or the floor that spans the trusses for multiple story homes of wooden construction. The sub floor, in better homes, is usually 3/4” plywood or OSB(oriented strand board) but some homes of cheaper construction may use a smaller thickness plywood or OSB or even some form of “masonite” type board. As I said the bathroom is the usual place where this sub floor fails due to simple rot caused by an abundance of moisture, usually under a long leaking toilet, the vinyl flooring has begun to come unglued or if you have ceramic bath tile the grout is allowing water from the tub or shower area to seep through. The homeowner usually isn’t aware of the problem until either a leak appears in an are below the bathroom or maybe you sit down on the toilet and feel that is unstable (rocking) or you feel a soft or bouncing feeling to the floor. Now comes the solution. The floor must be torn out and replaced from the sub floor up. Not an easy or inexpensive fix but it does have to be done and look at as an opportunity to make Momma happy with a new floor surface and to make yourself happy with that new “comfort height” Toto toilet that your neighbor has that you have been coveting. Don’t panic, the commandment says not to covet your neighbors ass not his Toto toilet. The following is a brief discussion group thread that briefly discusses the replacement of the subfloor and the common problems which arise and the answers:
Q: "Looks like I'm ripping the sub floor from the Bathroom up. The toilet Drain is on top of 1/4 Plywood (remember I said the sub floor should have been 3/4” at best). Do I remove the toilet drain and then place it back on top of the ¾” floor +concrete board (that’s the board used when you are installing ceramic tile, it provides a more stable surface) + tile or do I remove all the old 1/4 and install my 3/4 and use a few wax wings to set the toilet back now? This would keep me from having to remove the drain. I was looking and they want $20 for a new Toilet Drain comes in 3" or 4". What does a average toilet use. "
A: "The toilet flange should sit flush on top of the finished floor level with only the thickness of the flange above the finished floor level. It should be bolted securely to the floor.Then the toilet will seal properly with one wax ring as intended. Do not stack wax rings (or more than two anyway), because you run the risk of squeezing the wax into the pipe and clogging it when you anchor the toilet back down. You need to look at the size of YOUR drain (aka closet bend drain pipe) to determine what size flange that you need...usually 3" but could be 4".
In addition, it is important to rebuild the floor under the toilet because a leaking closet flange probably rotted the original floor. The 1/4" flooring is entirely too thin to be supportive. Ideally, you should peel the existing flooring back to the floor joists, raise the closet flange to the finish floor height by cutting into the vertical sewer drain below the floor and extending it the proper amount, replace the subfloor with 3/4" plywood, install the new finish flooring, and reset the toilet. Don't use more than one wax ring. If you find that you have to, something isn't right."
There was great info for the solution, kudos to the guys that provided the answer. The things to take away are 1/4” plywood or anything else is WAY TOO THIN for sub floor. Don’t take short cuts in repairing and replacing the toilet, drain and flange. Lastly avoid the temptation to use more than 2 wax seating rings to deal the toilet to the flange. You cannot imagine how many discussion group questions Ive seen where someone has installed a new toilet and had it immediately overflow everywhere because the excess wax rings had fallen down into the drain and completely occluded the drain line. By the way they immediately try to fault the manufacturer of the toilet….”the damn thing must be defective”!