in my upstairs bathroom the flooring under my toilet is depressed. in the past year and a half it has leaked a few times. each time i have replaced the wax ring. today i noticed that there is water leaking in to the kitchen cupboard (the toilet is right above this cupboard). the bolts holding the toilet to the floor are always loose, leading me to believe that the sublooring under my toilet is probably rotten. what should i do to repair this?

 

If you are lucky you may just need to replace the toilet bolts or upgrade the flange (the metal ring around the drain pipe that the bolts connect to) and then put a new wax seal down. If you pull up the toilet and the floor itself is mushy then you are going to have to replace the rotten floorboard. Take up any flooring materials and inspect the wood. Cut out the rotten section to the next closest floor joists and put new plywood of the same thickness back down. You may need to remove/redo the toilet flange, expecially if you have an old soft lead closet bend and wood screws.

The alternative is extensive rot, the toilet ending up in the kitchen when it falls through the floor and possible mold problems. Bite the bullet and get that thing fixed if it needs it.

 

Pull the toilet, inspect the damage, and remove ALL the subfloor where water damage occurred. Remove 1 foot past the damage and secure to the joists. If the joists are softened from water damage, sister new joists next to them to provide stability for the new closet flange.


Cut a 4 3/4" hole for the flange, use stainless steel screws for anchoring the new flange down.

 

To add a bit, the new flange should be centered 12" from the finished wall, and the flange bolted to the top of the floor with only the thickness of the flange above finished floor level.
Level the toilet when re-installing it (with beveled plastic shims made for the purpose, if necessary).
I highly recommend going with all pressure-treated plywood and lumber for any bathrooom flooring repairs. It will get wet again (not if, when), but the p-t won't rot.
Good Luck!
Mike

 

I, too, have buckled flooring under the toilet and a small place near the bathtub. Although I had the toilet replaced yesterday (and it's leaking, so the contractor has to come back again today), the floor problem remains. Even though this is a "do it yourself" forum, this is more than I can possibly do. What could I reasonably expect to pay to have a contractor come and replace the subflooring in those two spots? I can probably redo the tile on the entire bathroom floor myself, but this needs to be repaired first! If it helps, I live in Northern Virginia. Thanks!