Can I extend DWV pipe with coupler or reducer to bring it closer to finished floor?

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Dabronx02

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Hi,

First time here, but I've been reading all the great advice. Hoping I get some guidance.

I have a 4" ID toilet drain (DWV pipe) that is too low from the finished floor. Additionally, I do not have concrete anywhere near the pipe to mount a closet flange. So, my issue is two fold...

1) I need to add concrete so I can bolt closet flange, and
2) I need to bring pipe closer to finished floor because I can't find a closet flange that has a long tail pipe nor one that will go over the outside diameter of my existing drain pipe. All the inside fitting closet flange at the box stores would be installed too low from finished floor. And, outside fitting flanges (like the original one pictured) are not available.

Since I need to add concrete, my preference is to do this right and avoid closet flange spacers.

So, my questions are:

1) Can I install a coupler or reducer or glue extension pipe to add length to the DWV pipe to bring it closer to finished floor? And, if so, can I then use a 3 or 4 inch closet flange that inserts into or on top of the coupler or reducer or extension pipe? In short, I just want to know if the closet flange can ever go into a coupler or reducer and not leak.
2) When I add concrete around the pipe, do I need to wrap it with foam or can the concrete simply fill all around the DWV pipe?
3) If there's an online source for an outside fitting closet flange, please recommend.

See photos here:
https://www.dropbox.com/sh/yy2dygvlxhuo8fe/AABh4wisHG2ccNakC7sVYmYja?dl=0
AABh4wisHG2ccNakC7sVYmYja


Thanks in advance. Looking forward to your thoughts.

Ben

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Dabronx02

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Thanks for the quick reply. My concern with the 888-AM is that the diameter would be too small...It wouldn't fit snug. But, the length would be ideal. Any thoughts on whether a coupler/reducer are appropriate since I can't seem to find a suitable closet flange?
 

Reach4

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If there's an online source for an outside fitting closet flange, please recommend.
There are outside 4 inch compression closet flanges called "code blue". They come in 2, 3 and 4 inch lengths to reach down. However they may need more concrete cut away to provide clearance.

A 4 inch PushTite will probably reach far enough down, and if not, there is a way to extend those to whatever depth you would like.

Had I seen your initial picture before you started excavating, there would have been an easier answer, such as a Danco Hydroseat above the existing closet flange. Still, you might be able to mount a 887-GPM (PVC) or 887-GAM in (ABS) on a repair ring with ears. Or of course you could screw into your proposed new mortar ring.
 

wwhitney

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1) Yes, you can do that. But your pipe is just a bit too short, and adding a glue coupling may put the top of the glue coupling too high. So an extended closet flange may be a better choice, as others have suggested.

2) Yes, you should wrap the plastic pipe with some foam wrap. Concrete shrinks as it cures, and you don't want it to clamp down hard on the pipe.

Cheers, Wayne
 

Dabronx02

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I really appreciate the feedback thus far. I ordered two Sioux chef flanges to try. The first was the 887-GAM, which is slated to insert into 4" pipe; however, it's not working for me. I was expecting it to fit easily, but clearly I don't think it will work. The other is the 886 yet to arrive, which I ordered for it's long tailpipe but I have a feeling it will also not fit INSIDE my pipe.

The drain pipe in my concrete has a smooth outer edge, but the inside looks like it has a lip (pardon my jargon if wrong - feel free to educate me!). At first, I thought it was glue I could cut/sand away, but I think it's part of the pipe since it looks uniform around the pipe. In the picture attached, the red line represents the length of this lip being ~1/2 inches wide and the green line represents the lip (or whatever its called) that goes around the inside of the pipe. The screwdriver is intended to show that the pipe diameter is slightly larger below the green line. In another forum, I read that I need a flange called a "fitting floor flange" that fits INSIDE my pipe, but a google \ search doesn't yield any results. Is this a real term? Is there another name for it? More importantly, the flanges at home depot that fit "inside 4 inch" flanges are not compatible with my pipe.

So, can anyone tell me what the heck my pipe is called?

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Reach4

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I have a 4" ID toilet drain (DWV pipe)
How did you measure that?

Could the hole you see there actually have a 3.5 inch ID?

And what is the OD? 4.5 inches or something else?
 

Dabronx02

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How did you measure that?

Could the hole you see there actually have a 3.5 inch ID?

And what is the OD? 4.5 inches or something else?
Yes, OD appears to be 4.5 inches. (photo attached)

It appears to have ID of 3.75, which I thought is considered nominal 4" ID. (photo attached)
 

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Dabronx02

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Btw, starting to wonder if a reaming tool should/could be used to get rid of this 1/2 inch of ABS that is making it difficult to get insertable flanges to go in. Thinking that if I ream it out, I'll enlarge the pipe opening closer to 4" ID and then have better luck with flanges. Or, do you think it will damage the pipe since reaming tool is intended for removing fittings?

I still have no idea if this is a typical pipe end as I have described. Thanks again.
 

wwhitney

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You might try to determine if the ID of the pipe is 4" below the obstruction. [One way to do that is to stick the cloth down farther, cut a couple pieces of thin wood say 2-1/2" long, mark them so you can recognize when they overlap to make exactly 4" total, stick them down into the pipe below the obstruction, and spread them apart.] If so, it's surely normal Schedule 40 ABS with some slightly weird obstruction at the top. [Could it be the remnant of a wax ring with horn, with part of the horn stuck to the inside of the pipe?]

Your old flange was a 4" hub flange; was it not glued? If the exterior of the pipe is clean and you have clearance, you could try finding an extended 4" hub flange. Or gluing on a coupling; if that would be too high, you could use an internal pipe cutter to lower what you have (perhaps removing the obstruction), assuming your external clearance also extends down farther.

Cheers, Wayne
 

Dabronx02

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You might try to determine if the ID of the pipe is 4" below the obstruction. [One way to do that is to stick the cloth down farther, cut a couple pieces of thin wood say 2-1/2" long, mark them so you can recognize when they overlap to make exactly 4" total, stick them down into the pipe below the obstruction, and spread them apart.] If so, it's surely normal Schedule 40 ABS with some slightly weird obstruction at the top. [Could it be the remnant of a wax ring with horn, with part of the horn stuck to the inside of the pipe?]

Your old flange was a 4" hub flange; was it not glued? If the exterior of the pipe is clean and you have clearance, you could try finding an extended 4" hub flange. Or gluing on a coupling; if that would be too high, you could use an internal pipe cutter to lower what you have (perhaps removing the obstruction), assuming your external clearance also extends down farther.

Cheers, Wayne

Thank you Wayne. I will take your advice on confirming ID below the obstruction. My old flange was only glued on the inside so it easily popped off. An extended 4" hub flange would be ideal; just not having much luck finding one. If I opted for a coupler which brought everything closer to the finished floor height that I need, would I then simply install/glue a new (spigot ?) flange directly into the coupler?
 

wwhitney

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Yes, a 4" coupler could accept a 4" spigot flange. I would suggest having both in hand before gluing anything, you want to check for obstructions (like an external taper on the spigot flange that keeps it from fully seating in the coupling). That will let you determine the final height and whether the existing pipe would need to be cut a little lower (also whether you can just out the obstructed portion just to be rid of it). Allow yourself at least 1/8" margin on each joint, you want the final (stainless preferred) flange to sit on the finish floor (after patching/infill, if required), not above it.

Cheers, Wayne
 

Reach4

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It appears to have ID of 3.75, which I thought is considered nominal 4" ID. (photo attached)
https://www.engineeringtoolbox.com/ABS-drainage-pipe-d_1732.html says about 4.033. I expect you have remnants of the old flange there. There are common flanges that glue inside of a 4 inch schedule 40 pipe or outside of a 3 inch pipe (3.5 OD). So if you have the reminant of one of those, then you would expect about a 3.5 inch hole inside.

I have seen Youtube videos where people use heat to help peel off PVC. I don't know if that works with ABS.

You have that good outside surface, but you would need to remove some concrete to remove that. You would remove a little to glue a coupling there, and you would remove a lot of concrete to be able to use a compression flange. You need to get glue right the first time. Compression gives you do-overs if needed.

If you check farther down for pipe with 4 inch ID, how far down does that go before curving off?
 
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Tuttles Revenge

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Those circles on the flat side of the fitting are an indication that you're looking at a fitting, not a pipe. Of the several fittings I have on hand, the only fitting with those circle injection mold marks is a closet flange... . most fittings hubs are not as thick as what you have shown.
 

Tuttles Revenge

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Actually. I think I have the exact fitting you're looking at on my desk now. The ridges you feel on the inside are threads which makes this an inside 4" pipe cleanout body for a 3" threaded plug. Does it measure 2" to the bottom from the top?

rectorseal.jpg
 

wwhitney

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Actually. I think I have the exact fitting you're looking at on my desk now. The ridges you feel on the inside are threads which makes this an inside 4" pipe cleanout body for a 3" threaded plug.
That would mean that the ID at the level of the ridges should be about 3.5", right, to match the OD of a 3" Schedule 40 pipe? Since both a 3" pipe and a 3" plug should thread into a 3" FIP connection?

Cheers, Wayne
 

Tuttles Revenge

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That would mean that the ID at the level of the ridges should be about 3.5", right, to match the OD of a 3" Schedule 40 pipe? Since both a 3" pipe and a 3" plug should thread into a 3" FIP connection?

Even worse.. 3" is too small of a plug and 3.5" is a hair too big to theread in. Proprietary. But I still think is a Tomkap or similar device. Perhaps this drain didn't start its life as a toilet.
 

Reach4

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I think what we see are remnants of the original 4x3 closet flange that got cut out.
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Dabronx02

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https://www.engineeringtoolbox.com/ABS-drainage-pipe-d_1732.html says about 4.033. I expect you have remnants of the old flange there. There are common flanges that glue inside of a 4 inch schedule 40 pipe or outside of a 3 inch pipe (3.5 OD). So if you have the reminant of one of those, then you would expect about a 3.5 inch hole inside.

I have seen Youtube videos where people use heat to help peel off PVC. I don't know if that works with ABS.

You have that good outside surface, but you would need to remove some concrete to remove that. You would remove a little to glue a coupling there, and you would remove a lot of concrete to be able to use a compression flange. You need to get glue right the first time. Compression gives you do-overs if needed.

If you check farther down for pipe with 4 inch ID, how far down does that go before curving off?

See photo. Red line represents about 2.5 inches from the "obstruction" to the part in the pipe/fitting that it angles in. Green line measures about 3.5 inches from the "obstruction" to where I'd say the pipe really curves.
 

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