View Full Version : Replace closet elbow with PVC?

08-05-2007, 08:24 AM
Hello All,

First post here, so be kind. I'm going through a bathroom remodel and came across a problem. My current closet flange has two peculiar attibutes.

(1) It is a 10" rough in.
(2) It has a 5" flange.

So, I know that I can buy a 10", but my option are very limited when selecting toilets. And I'll have to fudge with the wax ring to accommodate this 5" flange.

I'd rather just replace the entire elbow and flange with PVC and give myself a 12" rough in.

I've included pics of my existing elbow. This bathroom had a raised floor that was taken out as part of the remodel and it will be rebuilt AFTER addressing my toilet flange/elbow issue.

(Click for larger picture)




So here are my questions:
(1) How do remove the existing elbow?
(2) How do I attach and adhere the new PVC elbow to the cast iron stack?
(3) Do you think this is DIY or should I hire a professional?

Thanks in advance for any/all replies... :)

Gary Swart
08-05-2007, 09:39 AM
My suggestion is #3 for all of your questions, and here's why. Making the transition from cast iron to PVC is of course done all of the time, but in your case, it seems to me that you have very little space to work with. A plumber might very well want to use cast iron rather than adapting to PVC. I commend you for realizing you should do this before you have put in your finished floor and then asking how you can fix the problem without damaging your floor.

08-05-2007, 09:40 AM

If you're not rich and can understand directions well...sure, it'll take longer.
If you'd like to get it done quick and right and can spare a few hundred....sure.
You might wind up having to buy tools that would bring the cost close to what you'd pay a plumber anyway...cutting cast iron needs at least a $150 sawzall (cheap brand) or a $300 snap cutter (again, cheap) and about 5-6 $4metal blades for 5" if you opt the sawzall route, as well as around $50 for stock.
switching to a 12" rough is what I'd do....10" and 14" roughs are less common and more pricey...you often pay more and have to wait for shipping to get the model you like.
Lastly....you sure thats not 4"?
Measure the inside diameter....not the outside.

08-05-2007, 10:25 AM
Hey Guys, thanks for the fast reply.

GrumpyPlumber: I can't say for certain that it isn't a 4", The last photo in my original post shows my measurement for the flange.

Here are some things that I'm just uncertain of:
I have an old house (1892 built) and I can't say for certain if I have a cast iron elbow or a lead elbow (I can't tell by looking at it). As I understand, using lead elbow here in Chicago wasn't an uncommon practice before the 50's.

Either way: I was under the impression that I could rent a 'snap cutter' to cut the cast iron / lead.

I've seen posts talking about cutting the cast and using a Fernco or No-Hub to marry the cast to the PVC. Cutting the Cast/Lead seems to be the hardest part of the equation - is this correct?

Lastly, **if** I decide to do it myself, would I attempt to remove the **entire elbow all the way to the stack** or simply cut it a few inches from where it meets the stack and marry it up with a no-hub/fernco?

Thanks again guys, its nice to know I can ask professions!!! :)

08-05-2007, 11:37 AM
That's a 4" pipe...the flange is mounted on the outside, so it is larger than the pipe. It looks like CI. I'd rent a snap cutter for about $20 or so and then replace the rest with an elbow, no-hub, and flange. Total costs, probably less than $50.

Note, it also looks like there may have been plaster walls...sometimes those are fairly thick. So, the actual offset may not be as far off as you think. If you measure from the studs, add maybe 1/2" for some drywall, then to the middle of the bolt holes to mount the toilet, that's your rough-in...my best is that it is more than 10", but may not be enough.

If it is closer to 12", then you may just be able to get the flange reset to the proper height once you get things back together.

08-05-2007, 01:16 PM
Hey jadnashua,

Ah, I see, so I *do* have a 4" then. And yes, it was lath (lattice) and plaster (boy was THAT fun to take down), here is a pic of the measurement to the stud:

(Click for larger picture)
http://vanaria.net/toilet/t5.jpg (http://vanaria.net/toilet/toilet5.jpg)

Looks like 11" from the stud, adding the 1/2" for drywall it would be 10 1/2" from the wall. Yep, all the more reason to remove and replace.

So, I'm gearing up my game plan here. I'd love to hear some critique or suggestions, or if this is a good gameplan.

From this thread and from what I read I should:
(1) Rent snap cutter and cut the CI a few inches in:
(Click for larger picture)
http://vanaria.net/toilet/t6.jpg (http://vanaria.net/toilet/toilet6.jpg)

(2) Connect the new PVC closet bend(elbow) with a No Hub fitting to the CI as follows:
(Click for larger picture)
http://vanaria.net/toilet/t7.jpg (http://vanaria.net/toilet/toilet7.jpg)

(3) Secure the new PVC elbow since it has to bear the weight of the toilet.

Am I understanding this correctly?

08-05-2007, 01:37 PM
The flange should be installed on top of the finished floor and anchored through it into the subfloor. That will anchor that end, the other end is fine at the connection to the existing CI. 4" is fine, but you might have better luck with the sweep of 3" line, with a reducer from the 4". The height of a pvc 4" might be too high. That's where one of the pros would be able to tell you right off. I'm just guessing.

Nicer to keep it 4", but consider, most trapways in a toilet are a little over 2" in diameter, so anything that will go through them will also go through a 3" line (and you have 4" very close).

08-05-2007, 02:29 PM
Jadnashua Wrote: "The flange should be installed on top of the finished floor and anchored through it into the subfloor"

Oh! In my case, I'm installing 3/4" plywood subfloor, then 1/2" Hardibacker , then tiles. So, that is to say that the flange will sit ON TOP of the Tiles?

Also, the NoHub Fitting will likely be made of neoprene, so is it safe to say that I won't need any kind of adhesive on the NoHub Fitting? Just slide it on the CI and PVC and tighten?

(Sorry for all the newbie questions, I just want to make sure I don't screw things up here)

P.S. Thanks for all the help, I **really** appreciate it. I'd love to hear from the senior members (Gary and GrumpyPlumber) as to the gameplan before I dive in. :)

Thanks again... :D

08-05-2007, 03:13 PM
Yes, a properly installed flange is on TOP of the finished floor. You can notch the tile so you don't have to drill through them to attach it.

A no-hub has neoprene, but it also has a metal sleeve over it to keep the two ends aligned.

08-05-2007, 05:13 PM
Okay, so I just got back from the local Home Depot and rented a snap cutter ($14 for 24 hours - good deal) and picked up all the necessary fittings, but I have two more questions:

(1) Is there a difference between a 4"-4" Fernco and a No-Hub-Fitting or are those the same thing? I didn't see anything called a No-Hub-Fitting so I picked up a Fernco. This is what I bought:


Is this the same as a "No-Hub-Fitting" ?? :confused:

(2) I noticed two different types of flanges, both PVC, but one has a steel flange and one with PVC flange. Is one better than the other?

Thanks again, and sorry for such simple questions...

08-05-2007, 05:20 PM
That isn't the right one...it can be used if you can find the metal sleeve they make for it. The right one out of the box is thinner rubber and has a metal sleeve over it. That type is only allowed underground where the two ends can be supported, otherwise, it can sag and create a problem with clogging.

The metal ring, if it is aluminum vs steel would be okay - it gives you some leaway when attaching the thing to the pipe since you can rotate it until it is in the right orientation prior to screwing it down. With the solid pvc ones, the stronger thing is to use the two narrow slots rather than the keyway shaped ones, but again, this has to be installed right or they won't allow the toilet to be oriented properly. they're stronger than the keyway, but less forgiving. Keep in mind that this is what holds the toilet to the floor, so strength is nice to have.

08-05-2007, 07:17 PM
I see. Thanks man, I've returned the Fernco and will seek out the appropriate No Hub Fitting.

Cutting through the cast iron was a bit tense since I've never done it before. I've already returned the snap-cutter. It certainly lives up to its name. Nice and even cut though. :)

As I see it, the difficult part is over, now to just get the correct fitting and piece it all together.

Thanks so much for all your help guys, it really gave me confidence knowing that I had someone in my corner... :)

08-06-2007, 12:42 PM
Alright, I picked up the No Hub Fitting made of Neoprene with the metal casing around it. Score.

Another question: do I put some kind of adhesive/silicon/caulk inside this NoHub before installing it, or will the tension from the metal-band be enough to keep it water-tight?

And if so, what kind of sealant would I use?

Thanks-a-million... :)

08-06-2007, 12:52 PM
As long as the CI is clean, the compression from the clamp should be all you need.

08-07-2007, 06:11 AM
Done! :)

Just thought I'd post the "AFTER" picture from my Before/After toilet series. ;) hehe

http://vanaria.net/toilet/t8.jpg (http://vanaria.net/toilet/toilet8.jpg)

Thanks again for everyone's help! :)

lee polowczuk
08-07-2007, 10:48 AM
Congratulations... not too long ago the guys on this board held my hand on moving a toilet and tieing it back in.

I had to smile at the snap cutter statement. I went through the exact same anxiety...but it worked almost like a knife through butter... for that cost of renting...why would you tear up X number of blades on a sawzall.

The other funny thing is you probably could have met the 4 hour minimum at HD and saved some money.. i know i could have, but was too beat to take it back in that time frame