Toilet Flange - 4x3 or drop flange in 3 inch PVC?

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Lonny D

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Hi,

I just replaced my subfloor and put in LVT in my half bath. I have 3 inch PVC coming up through my floor, but since I removed the previous flange, the pipe is slightly below the finished floor, about 3/4 of an inch. I bought 2 flanges, and can't figure out the best way to proceed.

Here is my dilemma/questions:

- If I use the 4x3 flange and cement over the 3 inch pipe, how much pipe has to go inside the flange? Is it ok as long as I have contact all the way around, or does the 3" pipe need to go as far inside the flange as possible, and would I need to extend the 3 inch drain pipe?

- If I use the 3" drop flange the goes inside the pipe, same question. How much of the flange needs to be inside the pipe? As long as there is contact all the way around it should be good right? Also, I typically use Better than wax seals, which can't be used with this type of flange due to the diameter being 2.5 inches. Does anyone know if the Danco perfect seal would work with this flange?

Thanks!
 

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Looks like the hub of your old flange is still on the 3” pipe.

I never use inside the pipe 3” pvc flanges. Some toilet horns hit the smaller diameter and won’t set.
 
Looks like the hub of your old flange is still on the 3” pipe.

I never use inside the pipe 3” pvc flanges. Some toilet horns hit the smaller diameter and won’t set.
Thanks for the reply - as far as the hub of my old flange, I look down the pipe and everything is uniform - same with the outside. Is this something I need to figure out how to remove, or could I just use a drop in 3 inch extender? would something like this work in this situation?

https://www.amazon.com/Magicmend-Pipe-Extender-Schedule-Pvc/dp/B00GP6813G
 
This looks like a joint between a pipe and a closet flange that’s had the flange portion cut off. I’m trying to make sure what you have before I start making recommendations. Measure the outside to outside of your pipe for me.
60AA534B-9040-4D7E-B717-A51312CEE31D.jpeg
 
So, you are 100% correct, thank you for pointing that out! I got up close, and started chiseling the remainder of the flange hub off the PVC pipe. The actual pipe outside to outside measures 3.5", and the inside measures 3". The actual drain pipe is 1 1/4 inch below the finished floor.
 

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Carefully clean out the pipe you’ve chiseled off and pull the rag out to take another pic looking down over the pipe.

I’m trying to determine how much room you have between the top of the pipe and the next fitting downstream.

Do not chisel anymore of the old flange off. It’s very easy to crack the pipe in your situation.

I may advise you to use an inside pipe cutter that chucks into a drill to cut the 3” pvc off below the floor, in the process you will remove the old flange hub.

I need to make sure you have room for the new fitting you’ll be glueing on. So we will need to take some measurements before you cut anything.

Be sure to stuff the rag back in the pipe. Don’t drop anything in the pipe ! It happens ! 🤣
 
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Carefully clean out the pipe you’ve chiseled off and pull the rag out to take another pic looking down over the pipe.

I’m trying to determine how much room you have between the top of the pipe and the next fitting downstream.

Do not chisel anymore of the old flange off. It’s very easy to crack the pipe in your situation.

I may advise you to use an inside pipe cutter that chucks into a drill to cut the 3” pvc off below the floor, in the process you will remove the old flange hub.

I need to make sure you have room for the new fitting you’ll be glueing on. So we will need to take some measurements before you cut anything.

Be sure to stuff the rag back in the pipe. Don’t drop anything in the pipe ! It happens ! 🤣
I appreciate the direction, the pic is attached.

I was wondering though, what are your thoughts on using some sort of drop flange that fits inside the existing drain pipe, and glue it in? I understand that reduces the flange diameter a bit, but can't really find info on whether or not they work just fine. Haven't found any horror stories on them either.

Thanks again for the direction.
 

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I don’t like those type flanges.

What’s directly below the toilet ? Basement, crawlspace, etc ????
 
I want you to measure down 5” from the top of the pipe and mark a line on the interior of the pipe.

Cut this line with an inside the pipe pvc cutter with a short extension chucked into a drill. Go slow and be accurate. Keep the rag stuffed in the pipe.

Once you get it cut you will glue a 4x3” bell reducer onto the pipe.

This will put the 4” hub of the reducer a couple inches below your floor. You will then lay a level across the finished floor and measure to the bottom of that 4” hub and to the bottom of your level. Cut a piece of 4” pvc square and 1/4” short of your measurement. You don’t want it to be long.

Now you have 4” pipe basically even with your finished floor. Glue a 3x4” Toilet flange with stainless steel flange into the 4” pipe.

Secure with stainless screws.

Use a fluidmaster thick wax seal without horn. Plain wax. Use brass closet bolts.

Set the toilet and caulk to the floor with adhesive caulk or 100% silicone.

You’ll never have to remove it again……it’ll last 30 yrs.

No cap 🤣
 
98DE4089-A68D-4098-9367-968439650ABB.jpeg
Here’s your 4x3 bell reducer.

Charlotte part #
03207

The above explains how I’d do it if I were to be on a service call. I’d charge you $400-500 to do that work.
 
You could try a 3” in the pipe flange but personally I wouldn’t because my way is better, I promise.

It corrects the problem forever and you can use any toilet you want. Some toilets may not sit on a 3” innthe pipe flange.
 
I want you to measure down 5” from the top of the pipe and mark a line on the interior of the pipe.

Cut this line with an inside the pipe pvc cutter with a short extension chucked into a drill. Go slow and be accurate. Keep the rag stuffed in the pipe.

Once you get it cut you will glue a 4x3” bell reducer onto the pipe.

This will put the 4” hub of the reducer a couple inches below your floor. You will then lay a level across the finished floor and measure to the bottom of that 4” hub and to the bottom of your level. Cut a piece of 4” pvc square and 1/4” short of your measurement. You don’t want it to be long.

Now you have 4” pipe basically even with your finished floor. Glue a 3x4” Toilet flange with stainless steel flange into the 4” pipe.

Secure with stainless screws.

Use a fluidmaster thick wax seal without horn. Plain wax. Use brass closet bolts.

Set the toilet and caulk to the floor with adhesive caulk or 100% silicone.

You’ll never have to remove it again……it’ll last 30 yrs.

No cap 🤣
Ok, so if I am understanding correctly, that reducer will drop right into the existing 3" PVC, and I glue in place. Got it. Also I addition to the reducer, I need a small length of 4" PVC, which after measuring I will glue into the hub of the reducer. After that, glue in the new 3x4 flange. Am I understanding that properly?
 
Ok, so if I am understanding correctly, that reducer will drop right into the existing 3" PVC, and I glue in place. Got it. Also I addition to the reducer, I need a small length of 4" PVC, which after measuring I will glue into the hub of the reducer. After that, glue in the new 3x4 flange. Am I understanding that properly?
Yes, that’s correct. You’ll only need a few inches of 4” pipe.

Inside pvc cutter
Extension for cutter
4x3 bell reducer sch 40 pvc
Pvc glue, blue…..no primer needed.
Few inches of sch 40 4”
4x3” flange with stainless ring
Stainless screws

You’ll have a professional repair that will last the life of the bathroom.
 
Yes, that’s correct. You’ll only need a few inches of 4” pipe.

Inside pvc cutter
Extension for cutter
4x3 bell reducer sch 40 pvc
Pvc glue, blue…..no primer needed.
Few inches of sch 40 4”
4x3” flange with stainless ring
Screws
You're the man, thank you. I'm gonna go grab the PVC stuff I need, and come back and get it done. I hate wax rings though, may just use a better than wax but I'll buy a jumbo wax ring without the horn just in case😆. Why don't you like the horn out of curiosity?
 
Pre drill for your stainless screws. Stainless screws have a tendency to strip if you just drive them in.
 
You're the man, thank you. I'm gonna go grab the PVC stuff I need, and come back and get it done. I hate wax rings though, may just use a better than wax but I'll buy a jumbo wax ring without the horn just in case😆. Why don't you like the horn out of curiosity?
The horn is simply a restrictor……with a proper set up like you’ll have they can only do harm.

I‘ve also knocked them through and into the pipe with my closet auger.

Some toilets do not flush properly with a horn. They can also deform over time and cause toilet clogs.

It’s a gimmick…….made for a guy who refuses to install a correct flange at the correct height. And they still fail…..

Trust me Lonnie. 🤣. I’ve been a plumbing slave now for close to 40 yrs.
 
Pre drill for your stainless screws. Stainless screws have a tendency to strip if you just drive them in.
Sounds good. I already have primer/cement - can I just use them vs the blue stuff? And one more question, why caulk the toilet to the floor? I thought that was a big no no due to the chance that there ever was a leak etc...
 
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Sounds good. I already have primer/cement - can I just use them vs the blue stuff? And one more question, why caulk the toilet to the floor? I thought that was a big no no due to the chance that there ever was a leak etc...
We caulk them to the floor. Some codes allow a little space in the rear to let water out.

Personally I caulk them all the way around.

Yes, you can use the glue you have if it’s not jelly. Use plenty of glue, it acts as a lubricant to assemble the pieces.
 

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