Toilet flange question

[Noreastern]

I am renovating a bathroom in a 1940s house. The toilet waste pipe and flange are original, cast iron. The old toilet flange was too high above the floor. So I cut off the old flange and am going to have a plumber set a new flange (cast iron again) once the floor is installed.

In the meantime, I installed a 3/4" plywood subfloor with a round hole cut for the cast iron pipe. The hole is a little too large--the new cast iron flange sits on top of it, but only barely, and can't be screwed down to it. I understand that ideally the flange should be anchored to the floor.

I am going to put down a layer of 1/2" cement board on top of the subfloor, then tile. Per a plumber's advice, I plan to set the flange on top of the cement board so it is flush with the finished tile floor. (He said that with a Toto toilet it is better to have the flange sit flush with the tile than on top of it. Toto confirmed this.)

Is it a problem if I don't anchor the new flange to the plywood subfloor? Would it help to cut a more precise hole in the cement board and anchor it to that layer even if there is no plywood underneath that portion?

 

[Reach4]

(He said that with a Toto toilet it is better to have the flange sit flush with the tile than on top of it. Toto confirmed this.)

I am skeptical that Toto said "it is better to have the flange sit flush with the tile than on top of it" or other words with that meaning. Are you saying the plumber said "Toto confirmed this" or are you saying "Toto confirmed this"?

I am not saying that flush is bad. I would be very surprised if Toto said that is better.

How is the new flange to be attached to the CI pipe? Will that be a compression flange, has it been leaded in, or what? Maybe you should put a repair ring over the new flange to take the force of the closet bolts. I am not a plumber.

I suggest you post a photo of what you will deal with. Provide dimensions.

 

[Sponsor]

 

[Noreastern]

I have attached pictures below. I contacted Toto and they also said the flange should be flush with the finished floor. Apparently, the part that connects to the drain pipe is wider on many Totos than other toilets. If the flange is too high, this connector can get stuck on the lip of the flange.

EDIT - the new flange will be attached with lead.

 

[Jadnashua]

A leaded connection is pretty robust, but it also depends somewhat on how the pipe is configured below.

Do you have access from below? If you do, you could add some blocking and make things tighter around the pipe so you can then screw the flange to the subflooring as well, while ensuring that you've left enough room to install the new flange.

What can happen with a leaded on CI fitting is if the top surfaced is not parallel with the finished flooring (i.e., one edge is sticking up), and because the CI flange is at the high end of acceptable things that will fit, if it's not done just right, the toilet may not fit. This can be true for any toilet. The toilets and flanges are designed for the flange to be on top of the floor, but there are millions of installations where it is lower. What you don't want is to have it lots lower, but if it's installed properly, it will (or should) work fine.

 

[Gary Swart]

I can't really argue that Noreastern's statement that Toto said that the flange location should be flush with the finished floor, I have to take his word that Toto really said it. However, I have been lurking on this forum for several years and the subject of flange location has come up numerous times and it has always come down to the proper location of the flange is on top of the finished floor. When a new floor is laid over the old leaving the flange recessed, there are ways to deal with that without replacing the flange, but never, not even once, has it been suggested that the proper setting is flush. OK, that said, your flange will be OK flushed, but you will need a thicker wax ring. I am more concerned that you do not have a good sub floor to screw into. I would suggest you cut a square piece out of that new sub floor, cut a new piece to fill that space with a better fit around the pipe. Sister some 2x4 pieces on the floor joist to make certain the joint between the original sub floor and the new piece are well supported. If it was mine, I'd put the flange on top of the finished floor and use screws long enough to go through the finished floor and the sub floor. But, it's not mine, so do it however you want and I'm pretty sure it will work just fine.

 

[Noreastern]

Thanks all for the comments. Putting aside the height issue -- cement board and tile will add about an inch above the plywood subfloor. What if I take a piece of 3/4" plywood smaller than the base of the toilet but larger than the current hole, cut an exact hole for the flange, then screw that piece to the plywood and anchor the flange to that? then I can just install the cement board and tile around this new piece.

That to me seems better than cutting out and replacing the current plywood. Am I wrong?

 

[Reach4]

In addition to carpentry, there are metal plates that can be used to span the gap and mount a closet flange.

I think you could also consider a compression cast iron flange as an alternative to lead -- although lead is very good for such flanges.

.

 

[Noreastern]

Alright, I've narrowed it down to two options:

(a) Cut out and replace that portion of the plywood subfloor with a new piece that has a correctly sized hole. Install cement board on top of this and anchor the flange through the cement board and plywood. The appeal of this option is that it would give me a sturdy anchor through two layers of flooring.

(b) Leave that piece of plywood in place. Cut a new small piece of plywood wider than the current hole but narrower than the base of the toilet. Cut the correct size hole in this piece, and screw it in place on top of the current plywood layer. Then anchor the flange to the new piece only. Install cement board and tile around this piece, which will be hidden by the toilet base. The appeal of this option is that I leave the plywood subfloor intact. It is a small room with few joists and I'd prefer to have an unbroken span across the joists if possible.

Which do you think is preferable?

 

[Reach4]

(b) sounds good. You may be able to find a piece of scrap of good outdoor plywood. A place that makes cuts for customers may have a leftover piece for cheap or free. Screw and glue if you want this to be strongest.

 

[Ryan Banks]

Appreciating all of this great information on toilet repair. Still learning the ropes as a greenie, but these forums help!

 

[Terry]

There are some thick flanges that could cause an issue with setting the bowl. If you have the bowl on hand, it would be nice to check that. I find it easier if the flange is a bit low rather than too high.