Does anyone have any advice or words of wisdom for the following project? Specifically, my questions are as follows:

  1. Is this most likely just a matter of replacing the entire upstairs commode / toilet assembly?

  2. Is that something that is easily done DIY? Or is it more complicated than it first appears? (It seems I can just purchase a commode assembly from Home Depot and remove the bolts in the old assembly and replace? (There might also be some sealing involved too to keep everything watertight I'm assuming.)

  3. Should I call a plumber to be on the safe side? If so, how much might they charge?

  4. Or, do I need a contractor because there is water damage in the floor boards? Do I need to replace the floorboards or can I just patch the ceiling drywall?


When the upstairs toilet is flushed, water apparently leaks thru the floorboard onto the ceiling in the room downstairs. The water damage in the floorboard suggests there is a plumbing leak above the floor.

The upstairs toilet shows evidence of leaking.

Fig. 1. Close up view of hole in downstairs ceiling caused by leak in upstairs toilet. Notice water damage to upstairs floor suggests leak begins above the visible piping.

Fig. 2. Medium angle view of Fig. 1

Fig. 3. Wide angle view of Fig. 1 showing room context for perspective.

Fig. 4. Toilet in upstairs bathroom. Blue stain on floor comes from toilet bowl water coloring tablets suggesting leak at base of the toilet.

2 Answers 2


It sounds and looks like the wax seal has failed. The good news is this repair is not hard. The bad news it is a "dirty job" .

Step 1 get a new wax seal at a plumbing or big box store just a couple of bucks. I like the ones with a urathane center they are a bit more expensive but 5 bucks is not a big deal. Also pick up some disposable gloves and a narrow putty knife (makes removing the old wax easier)

Step 2 turn the water to the toilet off and flush you want to empty the tank. If you have a wet vacuum suck the small amount left in the tank out and also drain the bowl, if no wet vacuum a small towel can be used to soak up the water and squeeze out down another drain.

Step 3 remove the supply line to the toilet. Step 4 remove the 2 bolts at the floor, 1 on each side.

Step 5 lift the entire unit by the base not the tankand lay on its side.
Step 6 clean the old wax seal off the bottom of The stool and the top of the toilet flange (the plumbing at floor level). Make sure to remove the rubber cone.

Step 7 take new seal and mold it to the bottom of the stool.

Step 8 this is the toughest part, pick up the stool by the base and position it over the bolts and lower it then press down, once the bolts are through I usually sit on it to help squash the seal a bit.
Step 9 install the washers and nuts tighten both sides a few turns each until snug, sit on the stool and see if it is loose if it is tighten a little more and check again (a stool that wobbles will shorten the seal life).
Step 10 replace the water line and turn on. Once the tank fills flush and verify everything is working with no leaks. Now just to clean up and dispose of the old wax ring & gloves and realize you just saved a bunch of $.

  • 2
    Good advice. The only extra thing I do is put the new wax seal in the fridge for a while to harden it up. Before doing all this, check the flooring around the toilet - if that needs replacing, do it now.
    – PeteCon
    Commented Jan 14, 2017 at 3:44
  • I like them warm so the wax can be molded in place but I have never tried doing it cold.
    – Ed Beal
    Commented Jan 14, 2017 at 3:53
  • 1
    @PeteCon Interesting idea. Sounds like it would slow down the molding process, which is good, as long as it isn't so cold that it cracks. Commented Jan 14, 2017 at 4:12
  • I'd also say that, if you have room, lowering the toilet onto the flange is easier with two people. Commented Jan 14, 2017 at 4:13
  • 3
    @PeteCon: Could you please explain and clarify why a colder, harder wax seal is desirable for this job as compared to a warmer, softer one? What advantages does the cold, hard seal offer? Ease of installation? Superior performance? What?
    – Mowzer
    Commented Jan 14, 2017 at 5:12

Remove toilet make sure flange isn’t broken clean flange replace toilet with a quality wax ring. Tighten toilet well but watch not to crack the porcelain use a mildew resistant caulk to seal around bottom of the toilet where it meets the floor.

  • 2
    I think it's a mistake to caulk around the bowl/floor joint. If the wax seal fails, I want to know about it quickly, so the wax ring can be replaced. If there's caulk in that joint, the leaking water will be contained, and sit there for awhile, and do further damage. Commented Jan 7, 2022 at 2:05
  • This doesn't add anything to the answer that's already been here for 4 years.
    – FreeMan
    Commented Jan 7, 2022 at 12:12
  • @FreeMan Are you referring to my comment or Andrew's answer? I think my comment does add useful information. Ed Beal's answer does not mention caulking the toilet/floor joint. Given Andrew's suggestion that the joint be caulked, this seems an appropriate observation. Commented Jan 8, 2022 at 17:27

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