I have an old house with the original plumbing (lead pipe from the toilet to the cast iron soil pipe. The toilet itself was replaced 20 years ago with a standard model. It has a metal toilet flange that appears to have been soldered to the lead pipe. Half of the solder is gone. The solder that remains seems to be the only thing holding the flange to the old and perfect ceramic tile floor. There are no bolts holding it to the floor. I can slip a putty knife under and around the whole flange. When the toilet backs up, water runs under the flange and is leaking into the kitchen below.
1. Can I fill the gap from the missing solder with bathroom silicon caulking?
2. Is there a better way than using the silicon caulking to repair this?
3. Should we or can we replace the metal flange with pvc?

It's not the flange I'd replace but the lead closet bend. However that's not what you asked.
First attach the flange to the floor using Tap-Con Cons.
1. Can I fill the gap from the missing solder with bathroom silicon caulking?
Not necessary if you secure the flange to the floor.

2. Is there a better way than using the silicon caulking to repair this?
After you secure the flange use a wax ring to seal the flange to the yoilet.

3. Should we or can we replace the metal flange with pvc?

If it were me I would replace both the closet bend and the flange.

Regards, tom

Old lead pipes are fun. There are a few ways to repair this. Different plumbers use different methods. The way I prefer is to remove the brass flange and use a compression flange. It has 3 allen screws in the top and has a rubber ring that expands to seal the lead pipe. While the better way is to replace the lead with pvc, that is not always an option. And when replacing the flange, you must secure it to the floor. You can do this with plastic anchors, tapcons, or if the wood is OK, just a long wood screww. Typically, on an old floor the wood is rotted around the flange.

"old lead pipes are fun.": Here's where we disagree Doug. Old lead pipes are a pain in the a$$.
1) There are few old time plumbers out there that can float a patch or wipe a joint on lead.
2) Since lead pipes are old they are more fragile then oher pipes due to wear and tear.
3) "i prefer is to remove the brass flange and use a compression flange."
A compression flange expands inside the pipe. Lead pipes aren't ridged enough to support a compression flange. I advise against using them on lead closet bends.
4) Lead pipes like galvanized pipes belong to a earlier generation of plumbing. They are outdated and should be replaced. Regards, Tom

It has been my experience that using a compression flange only has to expand enough to make the neoprene O-ring fit against the lead pipe and that does not take enough pressure to harm the lead pipe. And with the flange secured to the flooring all of the upward pressure is one the screws and not against the lead pipe.

And Tom you might be surprised how many of those "old time plumbers" that are still left out there. That was a time when plumbing was an art and a man had to know how to work with many different materials and equipment. Now a guy with a ruler and a hacksaw and a can of glue can do plumbing-like work but that does not make him a plumber.

Tom, I have had much success with the compression flange. I would love to replace the lead in those homes but typically, the people that own those homes are inclined to not spend the money to do that, plus floor repairs and/or ceiling repairs. Lest we forget, we have a person asking how to "repair" his toilet drain flange. And he said the solder has come off part of the flange and you were going to fill this gap with wax? I personally don't think you would do that. I think it slipped by you and you simply did not address it.

"lest we forget, we have a person asking how to "repair" his toilet drain flange. and he said the solder has come off part of the flange and you were going to fill this gap with wax? i personally don't think you would do that. i think it slipped by ya and you simply did not address it"

Oh I addressed it OK. "1. Can I fill the gap from the missing solder with bathroom silicon caulking?
Not necessary if you secure the flange to the floor.
Doug are you under the impression that the flange is there to make a water tight connection between the bowl and the closet bent?: It's not. The wax ring performs this function. All the flange does is secure the bowl to the floor. By using TapCons to secure the flange to the floor you have performed the samje as soldering the flange to the lead closet bend.. So I don't think that , " it slipped by you and you simply did not address it."
Let me take you back to a earlier time in plumbing when closet flanges didn't exist. Back then we set a toilet directly on the floor over a lead closet bend that's flared using a rope of plumbers putty for a seal. We then secured the bowl to the floor using wood screws. So before ya get all salty and bust my chops think about it. I dunno if you're a licensed plumber or not, ( I suppect not from your comments about rough in measures) I doubt if you've ever "established walls" on a virgin rough in. But if you are licensed I bet you haven't held it for very long. I'm not perfect, nor do I know awll there is to know about plumbing, (especially the new stuff since I retired) but what I bring to this page is over 50 years out in the field doing every aspect of plumbing, from residential to commercial, from single houses to high raise condos, from repair and service to troubleshooting warrenty complaints.
I stand on my record, where do you stand?

And Letmetellu,

"It has been my experience that using a compression flange only has to expand enough to make the neoprene O-ring fit against the lead pipe and that does not take enough pressure to harm the lead pipe. And with the flange secured to the flooring all of the upward pressure is one the screws and not against the lead pipe."

Perhaps you wouldn't expand the compression flange enough to break through the lead walls of a lead closet flange but are you saying it can't be done on a soft metal closet bend by a overzealous do-it-yourselfer? And if the lead bend is flanged, (as it ought to be) a compression flange isn't necessary. Cheers, Tom

Tom, I appreciate your answers about the flange. It must have slipped past me that there would not be a problem with a flange that had separated from the pipe.
And the expansion flange does not compress enough to split the lead pipe even if you wanted to.
You asked where I stand. Obviously far below you. I started in 1973 at 18 years old working in my father's business for 12 years doing plumbing and heating, then working strictly commercial for a time, then moving to the orlando area from pensacola to work there for about 15 years. Then moving to the atlanta metro area and been here for 6 years. In 1978 I got my journeyman license in Florida and 5 years ago I got my Georgia state unrestricted master license and the Alabama state master plumber license. I currently continue to hold all three. I have owned and operated a business in the atlanta metro area since August 4.5 years ago. Being a Florida plumber you may know my dad. He has been the Florida legislative director for the plumbing heating cooling contracters association for about the last 15 years. His friends call him louie. And his business is still in operation in pensacola.
Tom, I don't mean to be a pain. I am just posting my opinion about plumbing issues on this site.

Doug I don't feel you have to verify your credentials to answer questions on here, I think that if you know what you are talking about it will be obvious to others. The answers you have given to questions on here have been very satisfactory to me.
One more thing, if anyone wants to know I started plumbing and doing heating and airconditioning work in 1949. Up until last year I held Texas Master Plumbing License Number 27. I worked all that time, except for the time in the Military service. And I owned my own business for over forty years.
Keep up the good work Doug I enjoy reading your replies to others.

letmetellu, thank you.
From what I have seen in here tom is the resident pro. I agree with many of his answers and the ones I don't I try to be helpful to the one needing help. More than likely I have stepped on his toes. Actually it is his opinion and my opinion and in some cases we differ. I am not offended at him asking my qaulifications. It may be a valid question. In some other posts I feel like I answered him fully. I have the ducks.

And I thank you both for your participation. You both bring a lot to the plumbing page. I ran a solo act for too long and it's time I slowed down.
While I'm a practical plumber and find fault with a lot of the newer codes you guys are up on them much more then me and I recognize that. Keep up the good work. I consider you both valued members. This page needs you both, regards, Tom

Thank you tom.

Tom let me thank you, and also let me say that I think we all can have some input on the questions posed here. As you both know sometimes it would take an expert just to understand what the person posting was wanting to know. So if we come up with different ideas at least they will have a choice.

And then there's me, who would direct the poster to remove the lead closet bend and brass caulking ferrule from the cast iron hub, insert a Fernco 'donut', lever a piece of 'no-hub' cast iron pipe into the donut, 'no-hub' band a 4x3 cast iron closet bend onto the cast stub out, install a cast iron compression closet flange onto the 4" bell sticking above the floor and then cut the top of the 4" bell flush with the top of the cast iron flange with an angle grinder and cut-off wheel.

That's a lot of work, but it's what has worked for me in the past -- OTOH, I don't see anything wrong with the solutions offered up by the other experts.

[grinz] I bet you would

iamgrowler... you and I both have good ideas the only difference is that I was thinking of something that could be done without tearing up the floor or the ceiling below is there is one, I don't remember if this is an upstairs commode or not. If the floor was going to be torn up I would have done exactly how you said.

I would hate to go back the days of the neoprene, no lead joints, I had a jack type lever for things like you suggested above but for running long lines I had a five foot piece of 1 inch galvanized pipe with twenty-five pounds of lead at the bottom to drive them together.

[grinz] i bet you would


>chuckles<

I got to be able to sleep at night.

Y'know, the biggest issue I have a hard time with here is recognizing and fully appreciating the limitations of the person actually doing the work.

I can look at a 'Fernco' hub to pipe transition and instinctivaly know where to best place the blocking needed to lever the horizontal section of pipe into the 'donut' -- But I am at a loss to explain how to do this to the person who is actually doing the work.

iamgrowler....you and I both have good ideas the only difference is that I was thinking of something that could be done without tearing up the floor or the ceiling below is there is one, I don't remember if this is an upstairs commode or not. If the floor was going to be torn up I would have done exactly how you said.

I would hate to go back the the days of the neoprene, no lead joints, I had a jack type lever for things like you suggested above but for running long lines I had a five foot piece of 1 inch galvanized pipe with twenty-five pounds of lead at the bottom to drive them together.

I think the biggest difference between the advice I give versus the advice given by the other experts is that I am limited by my limited service experience -- When I'm facing the situation described, it's a remodel scenario where the floors are being thickened for tile or woodwork and the cast iron hub being tied into is already exposed from the underside.

Being UPC trained, rather than IPC or SPC trained also makes a huge difference in how I approach each question.

You did good... just keep it up... and I agree about the people you are responding to, you never know what they are capable of doing or what they might understand, or if they are a danger to themselves.

iamgrowler....you and I both have good ideas the only difference is that I was thinking of something that could be done without tearing up the floor or the ceiling below is there is one, I don't remember if this is an upstairs commode or not. If the floor was going to be torn up I would have done exactly how you said.

I would hate to go back the the days of the neoprene, no lead joints, I had a jack type lever for things like you suggested above but for running long lines I had a five foot piece of 1 inch galvanized pipe with twenty-five pounds of lead at the bottom to drive them together.

From lead and oakum joints at the beginning we went to neoprene gaskets. I used a 6 foot Johnson Bar to lever in lengths of 4" cast iron into a hub with a Duel-Tite gasket, and then we went with N0-Hub bands on our cast iron and from there to ABS and finally to PVC. Regards, Tom

If the flange was sepperated from the bend how would a wax ring 2 inches away from there stop water from leaking out if there was a back flow?