View Full Version : Cast Iron Flange Rusted Broken

04-13-2008, 02:55 PM
Howdy all - and thanks for being here and providing such great help!

In replacing our upstairs toilet we found that the cast iron flange was rusted and wrecked. From reading some of the threads in this forum, I think I have the proper solution, but I would love to hear whether I'm right or just completely out of my mind (my wife has her own opinions on that).

I'm thinking that I need to have a real plumber come out and remove the old cast iron flange. It seems to me that it might be best if I just had them put a new one on. I guess I'd prefer to go with cast iron again if possible.

Now, the only other problem is that some time ago some previous DIYer decided to raise the bathroom floor. So, the floor is actually (from the bottom up) joists, subfloor, tile, some sort of masonry or concrete filler, more tile. I'm thinking the best thing to do would be to pull up the floor all the way down to the joists, or the original subfloor if that's still in good condition, and fill back up using plywood or OSB, then lay my tile on top (making sure that the bottom of the closet flange is resting on the tile).

But, it seems that someone in the past thought that it wasn't necessary to have a subfloor available to fasten the closet flange to. They just packed it with masonry and/or some sort of hard putty like substance. Is that something that could work so that I don't have to tear up the floor? It doesn't seem right, but someone did it at least once before.

So, anyway, if you can see the attached photo, I have chiseled out around the closet bend and flange. Does any of what I'm thinking and doing make sense?

Gary Swart
04-13-2008, 04:19 PM
Your pictures didn't attach, but I think you're on the right track to replace the entire floor to the joists. It will be more work than just patching what is there, but if you do it right now, it will never have to be done again. You got away with the flange not being anchored down to the sub floor probably because cast iron has no give to it and held the flange OK. Done right, I see no problem with any kind of flange.

04-13-2008, 04:39 PM
Thanks Gary,

I think that must be the way to go. We're going to remodel in about 5 years when the kids are bigger, so we don't want to go too far, but it's not that big a bathroom anyway, so I think you're right.

The only thing I can't handle myself is removing the old flange, but that's what plumbers are for.

Don't know what happened to the photo. Maybe I should have just pasted into the body of the post.

Thanks again,


04-13-2008, 06:09 PM
It's not all that hard to remove a leaded joint if you have good access. If you don't want to whack the edge with a sledge and chisel (it will crack), then drill the lead out - make it swiss cheese, then pry the lead out and the flange will come off.

There are internally sealed clamping cast iron flanges (twist and set is one brand) that clamp and seal to the interior of the pipe (scrape the inside as clean and smooth as you can first).

You do want something there to screw the flange into - you don't want to rely entirely on the gasket seal to hold it in place. If you have access from below, you could possibly put a donut of ply and some 2x pieces all screwed together to hold it and give someplace to screw the flange rim into.

Then, in the 5-years or so, tear it out and put in a new subfloor, done properly. that would easily work until you are ready for that.

04-13-2008, 06:58 PM
Thanks Jim. I was thinking of replacing the flange with an internal at one point, but someones else elsewhere on this forum seemed to think that PVC and Cast Iron should never meet.

I've been whacking the masonry that someone put in around the closet bend, but I have been reluctant to take a smack at the flange itself. It seems so rusted on to the closet bend that I've been afraid of doing more damage. Maybe I'll give that a try.



Can't seem to get an image in this post, but here's a link to the image of the flange. Thanks much!


04-14-2008, 05:45 AM
It only takes a few minutes for a plumber to remove the old flange and install a new cast iron one. Cast iron flanges do not really require securing to the subfloor. Their connections are so secure and the pipe heavy, that it is almost impossible to flex them.

04-14-2008, 07:02 AM
Wow. Since I'm going to re-model in a few years it would be nice not to have to put in a new sub-floor now, but I'm starting to get a little confused here.

I'm worried that the pipe won't be enough. I'm replacing a toilet that was installed in 1994. The toilet developed cracks and by the time we took it up the flange was all rusty, the bolts were gone, and the wax ring was a joke. So, I'm worried about doing it the same way the previous homeowner did it (no subfloor). But, I have to admit, not having to put in a subfloor at this time is an attractive alternative.



04-14-2008, 08:35 AM
If a new flange is leaded onto the pipe, anchoring it as HJ indicates isn't a big deal. This is not something the average DIY'er can do easily or cheaply since it would be a rare person that had the tools or experience. Most pros can do this (or should be able to!). If you choose the homeowner choice of an internal sealing one, then yes, you should anchor it and only rely on the internal seal to seal, rather than hold the toilet in place, too. Either can work for a long time if done properly.

04-14-2008, 09:25 AM
The only thing I cannot tell from your photo is elevation.
I think this might be a nice spot for an oatey
twist and set. It sets inside of 4" pipe and does a real nice job.
The cast iron is solid as a rock in cast iron pipe!
The cast iron version and plastic versions are at the local homedumpster.

04-14-2008, 09:29 AM

04-14-2008, 09:30 AM
Hope everyone can see this!

04-14-2008, 10:19 AM
So, I assume that if I use an insert like this Oatey, I’ll have to do some cleaning up of the inside of the closet bend. Is there any problem with using a wire brush on a drill to smooth out the inside of the pipe?



04-14-2008, 11:32 AM
Yes, you want the inside fairly clean to ensure a good seal...a wire brush is fine.

04-14-2008, 01:35 PM
Hope everyone can see this!

Oh I can see it allright! About !/3 of it at a time!
Why don't you edit it as a url link!

The only problem with that type of flange is screwing it to the floor keeps it in position. As I recall the floor isn't going to hold a thing in position.

04-14-2008, 02:13 PM
Thanks Redwood.

I think if I can get the plumber who I have coming out to take off the old flange to put on a new cast iron flange then I will go with that. But, if I have to use an insert it seems like this one of Bombjay's is the way to go. But, in that case, I will definitely redo the subfloor. I may do the subfloor in any case despite maybe not needing to with a leaded on cast iron flange and this being only for the next 5 years or so, but I have an unreasonable need to make what I build really secure (you should see my kid's playhouse).