Toilet Flange Help...Please

[John Yogus]

I am not a plumber and my plumbing skills are just about none. So, would someone please provide insight to me on these couple of questions. FWIW, I'm updating my bathroom and will be laying down a new floor.

1) How high should my flange sit about my floor?
2) I currently have cast iron pipe. The current flange is correded very badly and I see corrosion further down the drain pipe at the first connection. Is this something to call a plumber about or just expected from cast iron and condensation?
3)During demo, I noticed that my subfloor was damp and started to get pretty gnarly. I never saw water on the linoleum, but it's apparent that it was there. Is it safe to assume my wax ring wasn't seated/sealed properly, or could this be a result of the corrosion issue from number 2 above?

Many, many THANKS to anyone who can offer insight.

[Prashun Patel]

If the pipe were so badly corroded that it was leaking, the water would likely run DOWN and wouldn't rot the subfloor. In my experience (and I've only changed out about 5-6 toilets in my time) that kind of damage is due to a leaky ring.

I can't speak to the corrosion in the cast pipe.

The flange bottom should seat solidly on the *finished* floor. It should be screwed through the finished floor into the subfloor. If you plan to tile, then this might mean adding rings under the flange to make up the different height btn the tile and the previous linoleum.

[Mike D Reynolds]

I've been plumbing for almost 31 years, so I'll take a stab at this. Depending on how much of your floor was damaged around the flange, it is possible there was a small leak from the bowl wax. Wood will wick water to a certain extent. Most of it likely ran down the outside of the pipe once the wood became saturated. There is also the possibility of condensate with pier and beam houses forming underneath the toilet and bath tub. Cast iron pipe corodes over time and the natural affects of urine help to speed the process. Even with the amount of water that is used to flush a toilet, there is not 100% dilution. These natural chemicals will adhere to the walls of the pipe and aid in the process. There is also the chance that a small amount of water stands in the pipe where you are seeing the rust down inside. tihs will also cause what you are seeing. The only sure way to check for leaks in the pipe is to plug it past where you are seeing rust and fill it with water. You can wacth the water level to see if it drops. Another way is to crawl under the house and check for wet ground. You can have someone pour water into the pipe while you are under there to see if it leaks. this is not as sure fire as the first suggestion but will sometimes work. Now what could cause a leak at the bowl wax is (1) just everyday usage. If the toilet moves the least little bit the wax can separate from the bowl. Since you have a wooden subfloor, this is very common because the wood will give with added weight. (2) Many small leaks are caused by the presure of a clog. If the wax is already weak, it is very common for it to separate form the bowl. (3) Plunging cauase far more leaks than you would believe. When you plunge you are forcing air and water through the toilet to free the clog. If that blockage is below the wax seal, which in many cases it is, than you are puting that pressure on the wax seal causing it to separate from the bowl. Form the second question, The bottom of the ring on the flange needs to sit on the finished floor and be fastened to the subfloor with screws. If you are using tile, you can purchase a bit that will drill through ceramic tile easily, but not so easily through porcilan tile. Depending on the thickness of the tile you can set the flange on the subfloor and stack your waxs, but it is not recomended. I wouldn't use more than 2. The type of flange you can find for cast iron will most likely fit on the inside of the pipe and either twist into place, or have set screws to draw the gasket up tight. Here in Texas, it is almost imposible to find lead ingots to put a regular type cast iron flange back on. What I usually do is cut the pipe below the floor and use at stainless steel band with a rubber gasket to adapt to PVC or ABS pipe, allowing you to use a PVC flange. The insert type flamges can catch the solids and toilet paper sometimes causing blockages. If you have access to a sawzall you can buy a carbide grit blade that will cut the cast iron pipe allowing you to switch to PVC. Hope this helps some with your project. If you have any other questions don't hesitate to send me a PM and I'll try to help.

[John Yogus]

Thanks again for the info. Floor is getting put in probably Mon and hopefully a full functioning bathroom in the near future.