Redoing toilet flange over tile with a 4" + drop to the drain pipe

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Hi all,
I am making a toilet repair. Here is where I am and what I am thinking. I have a 4 inch ABS DWV pipe that now sits open about 4 inches below the surface of the tiled floor which I think generally speaking is pretty far away.

The pipe elbows 90 degrees about 1.25 inch below its open top. So... I want to somehow connect a flange that will sit on top of tile once i put it all back together. I am a dyi enthusiast and am trying to do it "right" instead of fast. My time is not an issue.

You will note i removed the tile around the drain and cut away part of the sub-floor to allow part of the joists to be available to support a new piece of sub-floor i will cut and insert over the area. i will of course cut a hole in the new sub-floor piece to expose the pipe. And then i will cut a hole in a new piece of tile and put down cement board and the tile so i basically have a solid top over the drain pipe with a diameter maybe just a little bigger than the pipe. I think that's the right way to do it?? My biggest concern is what flange to use and how to connect it.

I have included a picture showing:
- the 90 degree elbow about 1.25 inches below the drain top opening.
- a 4" measurement line attempting to indicate there is 4" from the
drain opening to the surface of the tile. Of course that's hard to
see exactly when looking birds-eye as the picture is.
- a blue pen outline showing the exposed joist that will be used to
support my sub-floor insert. I have exposed joists on 3 sides for that support.



flange situation.jpg



Right now here is what i think are my choices:

1- use a 4" collar coupler. this coupler fits on the outside of 4 inch pipe. I believe I can push it 1 to 1-1/4 inch down over the current pipe before it hits the elbow. Then use a 3 x 4 flange with a 4 inch extension that i can buy locally. I will probably have to cut about 3/4" off the extension down to ~ 3.25" and it will go down the collar about 1.75 inches then.

2- Use 3 inch pipe inside of the 4 inch pipes to join them instead of a 4" outside coupler. Basically couple the 4 inch DWV pipe and a 4 inch flange from the inside instead of the outside.

3- I knew i needed something longer than 4" to connect to my pipe and no local places had anything. I didn't think they existed. But i found a 3 x 4 with a 6" extension on line! I could cut abut .75 inches off it and it would fit right into the 1.25 inches i have just before the elbow with just 1 gluing connection instead of 2 for the inside or outside coupler method.


My thoughts:
#1: It keeps the largest inside diameter available down to the elbow at 4 inches. That sounds like a good thing but i don't know if that is a particular advantage over having only 3.5 inches. Toilet openings are only ~ 2.25" so I don't know if its a big advantage having anything bigger than 3 inches anyway.

#2: I can't really see any advantage here. But i listed it just in case I am missing something.

#3: Advantage is just one gluing and it keeps everything inside going down. ie if there was a breach on the outside collar waste could potentially leak to the outside of the pipe. Disadvantage is that i am now reducing my pathway to the elbow to 3.5 inches from 4 inches. Question: is it somehow wrong to use a 6" extension flange?? I couldn't find any locally and wonder if they are just not popular or maybe just not needed enough to stock.

My conclusion: I think #3 is probably the best, but it that is mostly based on the idea that cutting my inside dimension to 3.5 inches does no harm over #1 where it is 4" all the way.

Additional question: I have shown a picture of the potential 6" extension flange that i can buy online. It has a painted top and is from Plumbfit. I don't see any other options for this type of flange. Does this brand and a painted top seem ok?

6 inch extension flange.jpg



Bonus questions: I was planning to sub-floor and tile pretty much up to the pipe diameter thinking this gives me the best protection in case of a leak and the most strength. This means i have to connect the flange through the tile, backer-board, mortar and sub-floor. Should i drill out a hole through the tile until the sub-floor so my screws don't have to go through the tile and mortar, or should i try to use tapcon screws long enough to enter the sub-floor. Or something else. I guess i am wondering if i should try to use a specific strong screw that just attaches to the wood and not be limited to a tapcon that is needed if going through the other stuff. (or something else)?

Thanks very much for any thoughts or advice you have to give.
 

Reach4

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I am not clear what the upper inch or so of "drain top" consists of. Is it a pipe glued into the elbow? Is it the elbow?

http://www.terrylove.com/forums/index.php?threads/push-in-toilet-flange.69469/#post-515556 including the link in #7 could be interesting if drain top was a pipe without enough free to glue a coupler onto. If you can glue a coupler onto that, you can do what you want pretty much.

If you choose a compression closet flange after you get a pipe to come up, you don't have to glue it. That gives you the freedom to not have to get it positioned right the first time.
 
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I am not clear what the upper inch or so of "drain top" consists of. Is it a pipe glued into the elbow? Is it the elbow?

http://www.terrylove.com/forums/index.php?threads/push-in-toilet-flange.69469/#post-515556 including the link in #7 could be interesting if drain top was a pipe without enough free to glue a coupler onto. If you can glue a coupler onto that, you can do what you want pretty much.

If you choose a compression closet flange after you get a pipe to come up, you don't have to glue it. That gives you the freedom to not have to get it positioned right the first time.

Thanks for your reply. The elbow is just one piece. ie the elbow starts someplace under the joist that you can't see and proceeds to the bend that you do see and upwards about 1.25 inches vertically. That is, I think i could put an outside coupler down around it about 1 to 1.25 inches before it would hit the bend. and i suppose if i put it on the inside i shouldn't go down more than that or i start cutting off the inside run of the pipe at the inside bend. I think i feel more secure with a gluing situation than a press-fit. 1 to 1.25 inches doesn't seem enough room to do a press fit plus you lose diameter don't you? I saw the link you mentioned and i'm like that fellow also in that once i tile i want this last at least up to my personal expiration or the jackhammer has to come out again. Do you see any problem just using the 6" extension flange i show? and inserting/gluing it about an inch below? I'm just trying to be extra careful so i don't have to visit this guy again. Trying to make sure i'm not missing anything or any tricks etc.
 

Reach4

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I am not a plumber.

I think you want to figure out what you have down there. You can measure, or you could get a 4 inch coupler and see if that is a 4 inch spigot end down there. Or is that a hub end down there that glues up to a piece of 4 inch ABS pipe?
 
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