Mistakenly cut out section of PVC drain pipe when removing closet flange

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Gothmartha

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I'm replacing the tile in my powder room and just finished with removal and prep of surface. As final step of the surface prep I wanted to remove flange because the tile I removed is 1/2" plus thinset and the replacement tile is 1/8" plus thinset. After watching many videos and reading as much as I could on line for the last two days I confidently began work.

Long story short, I cut out a 2" x 2" section of the pvc drain pipe that is above grade. Oh and I severely scored the bottom 2" of the pipe below grade mistakenly thinking it was the flange. (sigh)

In looking in the drain the white pvc I damaged is only a few inches long below grade and it feels like it's sitting on some type of lip/ledge of an elbow.

What are my options? Can I remove the entire piece of pvc and replace it? Do I need to call a plumber?

I'm relatively handy but this was my first time replacing a flange and despite all my research and talking myself through it, I screwed it up.

Thanks,
 

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Reach4

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What is the ID of the PVC? Your choices are 3 or 4 inches. How far below the new floor level does the side damage go? Did the damage at the bottom go all of the way through the pipe, or did you just make a part-way-through gouge down there?
 

Terry

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They make closet flanges that go inside the PVC pipe that are quite long. I sometimes cut them shorter if there is a fitting that prevents the full length.
On concrete, I use a rotohammer to drill 1/4" holes in the concrete so that I can anchor it to the floor.
 

Jadnashua

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If you can tell that the vertical riser goes into a hub, you can buy a tool that will ream the pipe out of the hub and let you glue in a new piece. At least a few companies make these tools, one is called a RamBit.


shows how to use one. Other brands are similar.
 
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Gothmartha

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The pvc riser is 3"ID and 3" long. The piece I removed from the riser is 1.5" long, but the scoring I made goes all the way to the bottom and is halfway through the wall of the piece. The riser is connected to or sitting in the lip of what appears to be to an elbow, not in a hub as mentioned above.

My first thought was to use a flange with a long inset piece as Terry mentioned above but I wasn't sure if I could cut it short enough to get flush to the floor because of the gasket without compromising the function of the piece, but it sounds like I can and it will still work! Because I scored the riser all the way down, should the inset pipe go below the bottom of the riser (just into the elbow)?

Could I achieve the same result by pvc welding a 2.875" OD piece of pvc inside the damaged riser and using the same type of flange that I removed (fits over the outside of the pipe)? Have I increased the risk of leakage if I do this? I'm not really excited about this option (suggested by spouse) because is sounds like the flange suggested by Terry addresses all the concerns.

Or should I chisel out the entire riser and replace it? I'm a little leery of this option because the riser is seated in the elbow and not leaking now and I'm loathe to introduce one more variable into this equation.

My spouse is going to question any path I take and I want to assure them the solution I choose is appropriate. I'm really on board with the inset replacement flange as it seems to remove many points of failure (leakage).

And this site is amazing! I was going to have a wasted Sunday fretting over how to address this and how much money this was going to cost when I had to call a plumber and they told me I needed to tear up slab, etc. Now I can begin tile installation!

Thank you all so very much!
 

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Reach4

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I am not a plumber. Two additional unconventional ideas come to mind. One would be to run some wide tape (masking or packing) on the ID over the fissures. Then carefully put some slow-setting epoxy down the fissures to fill the space. Remove the tape after hardening if it would come out. Instead of tape, maybe you could inflate a balloon in the hole.

The other one is to use a Danco Hydroseat. Mold wax to fit so that no gaps will remain after the Hydroseat is set. Then screw down the Hydroseat. If there is any, remove any wax that has flashed into the path. A long small steel ladle such as are use at salad bars could serve as a scraper. If the tile is porcelain, note that it is hard to drill that. The Hydroseat requires 4 holes to be drilled. It is possible the Hydroseat could be set into the concrete and the tile put around it. Then deal with it when mounting the toilet like any other nearly flush flange. I don't find dimensions on that horn. I would think it might be around 2.7 OD.

The Hydroseat can be fastened down by the holes in the 4 legs, but alternatively it could be fastened by 4 flathead screws farther in. So the legs could be on the tile, and the screws could go inside of the tile.

https://www.danco.com/product/hydroseat-flange-repair/
 
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Jadnashua

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I'm confused...the only way to solvent weld two pieces of PVC or ABS together is by the use of a hub. That riser you said goes into an elbow and you can see the end of it...unless I'm missing something...it is glued into a hub. WOrst case, you crack some concrete, and cut things out and replace. That's what a tool like the RamBit is designed to avoid.

FWIW, a toilet is designed to work with either a 3 or a 4" pipe...trying to find something that would fit inside of your 3" pipe is not a wise choice. The slide in toilet flange with the built-in gasket might work if it isn't too long, and will fit in what amount of riser you have left, but not if it wants to try to go around the elbow. Using an inside flange on a 3" pipe is asking for problems, though. You might get lucky.
 

Gothmartha

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This is where not being a professional is probably causing confusion because I'm not saying the right words.

The entire riser is 3" long - total - above and below grade. It appears the riser is sitting in or on a lip on a black elbow. Is the top of the elbow considered a hub? If you look at the pictures you'll see lots of purple pvc cement going down the sides of the elbow so I'm assuming the riser has been at least glued and if I'm lucky, not welded.

I probably could cut and chisel out the remaining pvc or try the ram bit - looks like they make a 3" bit. Again, I'm worried about not seating a new riser properly in the elbow and creating a leak.

If I were to use a plumber how expensive is a job like this? The area around the outside of the riser has already been chiseled out of the slab about an inch deep for the old 4" flange to sit in when it was placed over the riser. I'm hoping to install this new flange flush to grade not sitting on the tile.

I'm still leaning towards the slide in flange, cutting the extension that fits into the riser so it's just below the connection of the existing riser and elbow. There is about an inch of "vert" before the elbow bend. While reducing diameter isn't ideal this still seems like the solution that is least likely to leak.
 

newbplumber

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I am not a plumber. Two additional unconventional ideas come to mind. One would be to run some wide tape (masking or packing) on the ID over the fissures. Then carefully put some slow-setting epoxy down the fissures to fill the space. Remove the tape after hardening if it would come out. Instead of tape, maybe you could inflate a balloon in the hole.

The other one is to use a Danco Hydroseat. Mold wax to fit so that no gaps will remain after the Hydroseat is set. Then screw down the Hydroseat. If there is any, remove any wax that has flashed into the path. A long small steel ladle such as are use at salad bars could serve as a scraper. If the tile is porcelain, note that it is hard to drill that. The Hydroseat requires 4 holes to be drilled. It is possible the Hydroseat could be set into the concrete and the tile put around it. Then deal with it when mounting the toilet like any other nearly flush flange. I don't find dimensions on that horn. I would think it might be around 2.7 OD.

The Hydroseat can be fastened down by the holes in the 4 legs, but alternatively it could be fastened by 4 flathead screws farther in. So the legs could be on the tile, and the screws could go inside of the tile.

https://www.danco.com/product/hydroseat-flange-repair/

+1. I would mask off that split and epoxy that puppy.
 

Jadnashua

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A typical elbow has hubs at both ends, and yes, something like a RamBit is specifically designed to ream out the pipe so you can insert a new pipe in the restored socket of the hub. A new hub is slightly tapered...after the RamBit, it won't be. Be generous with the cement. The typical joint with plastic pipe uses a cleaner (the purple you see) that both cleans and starts to soften the surface, then the cement has some strong solvents and dissolved plastic in it that melts the surface, allows you to insert the pipe all the way (the taper helps to center the thing and make the end a tighter fit), and when the solvent evaporates, the things are fused, or solvent welded together. The extra dissolved plastic in the cement helps to fill in any gaps.

Epoxy is not recommended...yes, it might work for awhile...a properly installed cemented joint will last forever unless something stresses it and cracks it somehow (or you cut it!).
 
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