CI Toilet flange - Inside or Outside??

My question is whether there's any reason to go to the trouble of making room for an outside mount toilet flange, rather than using an inside mount. Either flange will be all steel/CI.

Background
I'm refurbishing a basement half bath, on slab, including replacing floor tile and the current mounting setup for the toilet.

Current toilet mounting consists of 4" CI with a thin steel flange mounted above it (not connected to the pipe) covered by a lead sleeve "top hat" that goes down into the pipe. The rusting flange is anchored with four rusting screws going into plastic anchors set into the concrete. Concrete touches pipe all around, so would require cutting back to make room for an outside mount flange.

I do plan to use lead anchors and stainless screws.

TIA.....

If your replacing the tile and the tile height will be the same and the flange is not broken there should be no reason to change the flange unless the pipe below it is compromised which it may be and has been repaired with a lead covering.

If you do replace the flange I would bust up enough concrete so you can eliminate the lead and transition from CI to plastic with a rubber coupling.

I used an inside-mount flange too. My inspector says there's a marginally higher risk of clogs with an inside mount, but it should be fine. When you have a choice and doing an outside mount is not that much work, it's apparently a better choice, though.

Cass said:

If your replacing the tile and the tile height will be the same and the flange is not broken there should be no reason to change the flange unless the pipe below it is compromised which it may be and has been repaired with a lead covering.

If you do replace the flange I would bust up enough concrete so you can eliminate the lead and transition from CI to plastic with a rubber coupling.

Click to expand...

I believe I'm looking at the original installation of this toilet, done in 1989 as part of finishing the basement - - not a repair job. Without tearing it out, I'm only speculating as to what critical purpose the lead sleeve serves beyond bridging the gap between the flange and the pipe. I think the pipe comes up (close?) to the level of the concrete, but will investigate further.

I would like to upgrade the bent/rusting flange and attaching screws at this time while everything's convenient. Also, the concrete needs leveling which will raise the finished height, but nothing that couldn't be handled with a quarter or half inch extension flange.

Which brings me back to my original Q, with an added assumption:

Assuming the CI pipe extends to the floor level in good condition, is there any reason to do extra work to fit an outside mounted (no caulk) flange, as opposed to an inside mounted (no caulk) one?

Can't you find a way to lead a deeper or longer cast iron flange back on. It would be the best way to do it. Personally any other way is almost Micky Mouse.

As a DIYer, I don't even attempt to do lead, but will call a pro of that's the only reliable long term solution.

I hear you saying that the Oatey, Jones-Stephens, et. al. flanges that compress a neoprene seal are all Mickey Mouse cob jobs.

Is that the consensus of the pros here?

They make a PVC flange with a stationary gasket that is tight against the inside of the pipe as you slide it in.

Installing an inside the pipe flange is only slightly less desirable than outside, like prashster said. PVC should work fine if secured to the floor correctly. There are literally 100s millions in service today that work fine.

Cass said:

They make a PVC flange with a stationary gasket that is tight against the inside of the pipe as you slide it in.

Installing an inside the pipe flange is only slightly less desirable than outside, like prashster said. PVC should work fine if secured to the floor correctly. There are literally 100s millions in service today that work fine.

Click to expand...

I've seen the Oatey Twist-N-Set PVC version

http://oatey.com/apps/catalog/showskus.asp?ctg=11&subctg=3&prodgrpid=363

at the big orange box, and a comparable CI version at the big blue box. Either seemed like the easiest reliable way to go, but I see too many S-traps in those aisles to just assume that because a product exists on their shelves, it's a good idea to use it.

Upon closer inspection......

What comes up flush with the top of the slab appears to be the hub of a 3" CI quarter bend. So, I'm looking for a flange that goes into the hub.

Pasco Specialty shows a flange for 3" no-hub that they say can also go into a hub with a neoprene gasket. So I'll check with a local suppy house for that or a comparable item.

good point

Good Point about the s-traps Ted. I have learned on this forum that s-traps are unacceptable, yet If I go to my local hardware or any for that matter they pull an s-trap off the shelf and give it to me if I need to do a drain. Why is that? I just installed an s-trap for a pedestal sink. The drain came up through the floor, so I don't know how else to handle it...
Not trying to steal your post. But I had to respond when I saw your point about s-traps.

Molo

An inside flange on a 4" pipe is okay, but you're pushing the limits a little with one inside of a 3" pipe. Some toilets have a 3" trapway, and you'd be adding a significant restriction right there. The walls of the thing are likely in the order of 1/4", so your opening would be down to 2.5"...not good. I'd try to get it on the outside of the pipe.

jadnashua said:

An inside flange on a 4" pipe is okay, but you're pushing the limits a little with one inside of a 3" pipe. Some toilets have a 3" trapway, and you'd be adding a significant restriction right there. The walls of the thing are likely in the order of 1/4", so your opening would be down to 2.5"...not good. I'd try to get it on the outside of the pipe.

Click to expand...

My analysis:
I'd be going inside the hub of 3" pipe with the equivalent of 3" pipe, giving the full 3" (nominal) ID for passage of the toilet "output". I'm mounting a Toto Drake, with 2.125 inch trapway. I don't see any restriction.

Am I missing something?

Missed that it was a hub. The hub inside diameter should be around 3.5" or so (a little bigger probably). Is this what you have? If so, it should work.