So, last week I was doing some repair work on a home to take care of issues found during a structural pest inspection. All in all for it’s age this home was in good condition. However the inspector did find a problem during the crawl space inspection that otherwise was going unseen from within the bathroom itself. What was discovered is that water had been leaking past the toilet wax seal, leading to rot in the subfloor. This was noted in the pest report along with a picture showing evidence of some rot in the subfloor from underneath where it is cut to go around the toilet drain.
The bathroom floor was constructed with 1 1/8″ plywood subfloor. The finished floor was constructed with tile backerboard underlayment and porcelain tile. From above the floor it all still appeared to be solid, the toilet appeared to be mounted solid and did not move around. Now, one reason for this toilet to appear from above not to have a problem was the fact that the toilet base had been caulked to the tile floor.
After removal of the toilet it was immediately evident that water had been leaking past the wax seal for quite some time. Since the toilet base was sealed on to the tile floor all the water had been held inside that area keeping the subfloor quite wet and eventually leading to rot. After necessarily removing the tile flooring down to the subfloor it was, first evident that someone really did a good job of installing the tile itself and would have continued to last for years to come. Second evident, was that since the leak was coming from above the rot was even worse than was evident from below. A section of approximately 9 sq ft needed to be replaced including some of the floor framing as well.
In the first picture is the floor I just mentioned, the cast iron closet flange is intact, but the wax seal had leaked for a long time. The result is fairly extensive dry rot damage to the subfloor. In the second picture, from a different toilet repair, the steel closet flange is rusted and needed replaced. You can somewhat see in the picture that the flange wasn’t even attached to the subfloor as it should have been. This allowed the toilet to move around and leak past the wax seal. As a result you can see there’s very little left of the wax seal.
While admittedly there seems to be differed opinions on whether the toilet should be caulked and sealed to the finish floor as part of regular installation methods, I prefer not to caulk the base of the toilet, in effect gluing it down to the finished floor. As long as the finished floor is level, as it should be, the toilet should sit relatively tight all along it’s base. It should also not move around from being pushed.
While I will continue to advise to my clients that the toilet not be caulked/sealed to the floor during installation, if you MUST have it sealed as a personal preference you should plan to have a regular inspection done. A regular inspection would involve flushing the toilet and inspecting from underneath if accessible, to insure that no water is appearing after making it’s way past the wax seal. This obviously isn’t even really possible for slab floors or toilets located above finished living areas below such as an upstairs toilet. If the toilet is not sealed to the finish floor, a bad wax seal will be more evident as water will tend to leak from under the toilet around the base. You can also periodically check that it’s still tightly sealed by checking the toilet doesn’t move around. A properly tightened toilet with an intact wax seal should not move around on the floor by grabbing the base and pushing side to side.
Of course I’ve replaced MANY toilets over the years and have seen this and other problems many times as well. Rotted subfloor, water damaged finish floors, and mounting flanges that rusted out and had to be replaced due to continual water leaks that went unnoticed. If you do insist that the base be sealed to the floor, you definitely should leave a gap around the back edge of the base. This will sometimes still allow a leaky seal to be evident due to water still has a place to possibly escape from under the toilet base. To note though, the particular toilet that brought me to post about this did have a gap in the rear but did not show that water was indeed leaking past the wax seal. The water was being held more toward the front instead.
Do keep in mind, wax seals should also be considered a maintenance item. I recommend replacing the wax seal of course anytime the toilet is removed, but also when the toilet is noticed to be loose and needs to be tightened. I also recommend replacing the wax seal somewhere within 5-10 years even when no other problems have been noticed depending on several factors . It’s cheap insurance for something that could potentially cost a whole lot more to repair the water damage caused by a leak.