Author Topic: Installing subfloor; cut waste lines for toilet?  (Read 601 times)

Healthie

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Installing subfloor; cut waste lines for toilet?
« on: November 04, 2018, 09:03:59 AM »
I'm installing a new subfloor in my bathroom and the wasteline (copper) has a flange on it (plastic) which prevents me from laying down the subfloor. My plumber friend recommended these steps:

1. cut toilet flange off the pipe.
2. glue a 3" coupling onto the pipe.
3. glue + screw subfloor down.
4. drill 4" hole through subfloor where the flange is (could I do this prior to installation and prevent sawdust in my pipe?).
5. cut 3" pipe to fit between 3" coupling below toilet and the new toilet flange.

Is there a way of installing a new flange without having to cut my wasteline? In all the toilet flange replacement videos I've watched they have cut the current flange off with a mini hacksaw and installed a new flange without having to cut the wasteline pipe at all.

J Boogie

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Re: Installing subfloor; cut waste lines for toilet?
« Reply #1 on: November 05, 2018, 08:51:28 AM »
When I replaced the subfloor in my bathroom, I simply used two different pieces of plywood with a semicircle cut out of each side so they could snug up under the existing flange. Didn't have to replace/cut either.

I've never heard of copper being used for drain. That's kind of weird. Cast iron, ABS, PVC... never heard of copper being used as a drain pipe.


CptCool

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Re: Installing subfloor; cut waste lines for toilet?
« Reply #2 on: November 05, 2018, 09:48:15 AM »
Ya, I'd do what j boogie did. Option 4 works too, I'd measure/cut before installing.

Make sure that adequate support is there underneath. Might need to add some blocking between the joists to support the joints in the subfloor

J Boogie

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Re: Installing subfloor; cut waste lines for toilet?
« Reply #3 on: November 05, 2018, 10:10:32 AM »

4. drill 4" hole through subfloor where the flange is (could I do this prior to installation and prevent sawdust in my pipe?).


If all goes as planned, sawdust will be one of the nicer things your pipe will see :)

I don't think you need to worry about it. Generally it's just supply pipes that you want to protect as you don't want debris getting in any of your finish valves. So they'll often be capped even if there's a shutoff valve. The reason you often see caps on drain lines is to keep the sewer gas out in the absence of a trap.

Editing to add that you are wise to ensure any major chunks stay out of your drain. It's an easy way to keep major clogs from happening and stray pieces of wood do have a way ending up in the worst possible places. Also in general cutting/preparing materials in an ergonomically comfortable workspace before installation makes much more sense than trying to cut/cut penetrations for subfloor in the same room you're installing it in. If your space is big enough and you're making enough cuts, for smaller pieces it's great to have your tools close at hand to save time. But definitely have a separate work station for things like subfloor/drywall or full length stud cuts.
« Last Edit: November 05, 2018, 10:21:51 AM by J Boogie »

BudgetSlasher

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Re: Installing subfloor; cut waste lines for toilet?
« Reply #4 on: November 05, 2018, 05:19:39 PM »
When I replaced the subfloor in my bathroom, I simply used two different pieces of plywood with a semicircle cut out of each side so they could snug up under the existing flange. Didn't have to replace/cut either.

I've never heard of copper being used for drain. That's kind of weird. Cast iron, ABS, PVC... never heard of copper being used as a drain pipe.

I did that for one toilet that have a PVC waste line. . . turns on that put enough stress on the pipe further back to cause a crack at a fitting and leaking into the basement.

on the more expensive route I have seen speciality toilet flange removal tools (that look like a whole saw with a guide) advertised. But have never seen them used.

J Boogie

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Re: Installing subfloor; cut waste lines for toilet?
« Reply #5 on: November 06, 2018, 10:24:56 AM »
When I replaced the subfloor in my bathroom, I simply used two different pieces of plywood with a semicircle cut out of each side so they could snug up under the existing flange. Didn't have to replace/cut either.

I've never heard of copper being used for drain. That's kind of weird. Cast iron, ABS, PVC... never heard of copper being used as a drain pipe.

I did that for one toilet that have a PVC waste line. . . turns on that put enough stress on the pipe further back to cause a crack at a fitting and leaking into the basement.

on the more expensive route I have seen speciality toilet flange removal tools (that look like a whole saw with a guide) advertised. But have never seen them used.

There would be no stress to put on the pipe - unless your previous floor was significantly out of level and the toilet drain was at a low spot. Or unless you jerked it up higher than it needed to go or shoved it sideways when sliding the new subfloor in place. No judgment if so, I've made too many dumbass moves to cast judgment on anyone. There's also the possibility that the PVC joint wasn't welded (the PVC cement technically creates a "welded" joint).

Genuinely curious how this happened though - PVC is pretty damn strong, flexible and the joints should be too. However the joints aren't always made with that purple primer, so that factor could be in play.

BudgetSlasher

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Re: Installing subfloor; cut waste lines for toilet?
« Reply #6 on: November 09, 2018, 05:59:19 PM »
When I replaced the subfloor in my bathroom, I simply used two different pieces of plywood with a semicircle cut out of each side so they could snug up under the existing flange. Didn't have to replace/cut either.

I've never heard of copper being used for drain. That's kind of weird. Cast iron, ABS, PVC... never heard of copper being used as a drain pipe.

I did that for one toilet that have a PVC waste line. . . turns on that put enough stress on the pipe further back to cause a crack at a fitting and leaking into the basement.

on the more expensive route I have seen speciality toilet flange removal tools (that look like a whole saw with a guide) advertised. But have never seen them used.

There would be no stress to put on the pipe - unless your previous floor was significantly out of level and the toilet drain was at a low spot. Or unless you jerked it up higher than it needed to go or shoved it sideways when sliding the new subfloor in place. No judgment if so, I've made too many dumbass moves to cast judgment on anyone. There's also the possibility that the PVC joint wasn't welded (the PVC cement technically creates a "welded" joint).

Genuinely curious how this happened though - PVC is pretty damn strong, flexible and the joints should be too. However the joints aren't always made with that purple primer, so that factor could be in play.

I don't recall prying it any higher than needed to slip a new 7/16 layer of subfloor under it, but I do know that other PVC in that area is seems to be a little "pre-stressed" or already pulled tight from some unknown project.

It could have been a welding failure. Most of the original PVC in this house does not show the purple from a primer, but there are clear options and I know more than a few old timers that just use either bulk acetone or bulk MEK instead of primer.

I have seen copper used as a waste pipe, but that is in houses 1950 and before.


jpdx

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Re: Installing subfloor; cut waste lines for toilet?
« Reply #7 on: November 20, 2018, 01:24:11 AM »
Sawdust in your drainpipe doesn't matter, but it's good practice to stuff a rag in the pipe to prevent tools from falling in and sewer gases from coming out.