Move the toilet across the room - what am I missing?

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ScaredNewb69

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As a longtime DIYer who has also worked in the trades a bit - but done only a tiny bit of plumbing - I'm considering moving a toilet as part of remodeling a 3/4 bath in my house.
I had been planning to just leave all the plumbing as is, frankly because I was intimidated by it.

But the subfloor around the old flange had to be replaced, so I ended up cutting the flange off anyway, and when I got to looking, it actually seemed pretty straightforward.

What I'm considering is moving the toilet diagonally across the room. The current flange is (was) about 10" directly above the main drain line. The new location would be two joist bays downstream and about 48 inches off to one side of that line.

If I've got room to slope it, is there any reason I can't just (1) cap the current tee (2) cut in a new sani-tee or wye 32" downstream (3) run new tube to a sanitary bend below my new location, and drop a flange + tail onto that?

I think (will confirm in the morning) that would put me on the other side of the tee where the shower drain joins (downstream instead of upstream), but route not leapfrog any other inlet/branch, if that matters.

EDIT: From other research I now see I apparently need to ensure (since I have 3" line) that I'm within six feet of the stack, unless I want to add a supplementary vent (which I definitely don't).

Thanks in advance!

Screenshot_20230203-232536.png
 
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Reach4

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Is there any drainage coming I from the right of the picture?
What is next downstream? Something vented like a lavatory or a combined lavatory+shower?
 

ScaredNewb69

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Is there any drainage coming I from the right of the picture?
What is next downstream? Something vented like a lavatory or a combined lavatory+shower?
Yes, upstream there is a washing machine in the adjacent room to the right. I assume that's the right-have terminus (upstream end) of the main drain line.

To the left is another lav+shower+sink, although it's a room away and might be on it's own drain, I'm not sure.

Thanks for your reply
 

Reach4

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Yes, upstream there is a washing machine in the adjacent room to the right. I assume that's the right-have terminus (upstream end) of the main drain line.

To the left is another lav+shower+sink, although it's a room away and might be on it's own drain, I'm not sure.
In that case, you will either need to add a dry vent to the toilet line, or you will need to route one or more vented bathroom fixtures to joint the toilet waste before the toilet waste joins the laundry waste.

Your current arrangement is not allowed by code either.
 

wwhitney

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So to provide a complete answer, please post a floor plan showing all the DWV pipes and fixtures in the bathroom and everything upstream, along with all the dry vent takeoffs.

Cheers, Wayne
 

ScaredNewb69

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Yeah, it's a mobile home so it's not surprising that it's not to code as-is, even though it's original construction. I even noticed the flange for the wc I just pulled dumped into a straight tee on its back. I'm pretty sure the venting on most of the system is subpar, too, given the number of roof penetrations or lack thereof.

That said, given that it works fine as-is (and has been working fine for about half a century at this point) I'm not exactly inclined to start ripping open walls/ceilings to run vents to bring it from 'works fine' to 'technically correct.'

If anything, between the choice of slapping a new flange on the existing *straight* tee and closing it back up, or capping the straight tee and connecting via a new sani tee/wye a foot away, even if I didn't add a vent, it seems like I'd be improving the situation just by dint of having it join the line via the correct fitting.

And I missing something that makes a vent critical in the new location, given that it's evidently not critical in the current location?
 

Reach4

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Functionally, without regard to code, your marked up picture is better than the original IMO, if that new fitting is a "combo" (combined 45 with a wye).
 

ScaredNewb69

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In that case, you will either need to add a dry vent to the toilet line, or you will need to route one or more vented bathroom fixtures to joint the toilet waste before the toilet waste joins the laundry waste.

Your current arrangement is not allowed by code either.
Would a mechanical vent in an adjacent cabinet (vanity) work?
 

ScaredNewb69

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Functionally, without regard to code, your marked up picture is better than the original IMO, if that new fitting is a "combo" (combined 45 with a wye).
Thank you for your reply. Would adding a mechanical vent to the toilet arm (branch?) improve it appreciably, or would I need to add/join a roof vent to get the benefit? There is an adjacent vanity that I am thinking could be an easy location for a vent for the wc arm.
 

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IMO, a mechanical vent in the toilet arm would not add much if any performance. The toilet needs air to get out of the way IMO. Others may have other opinions, and they may be more correct than mine.

While the laundry vent is officially not allowed to serve as a wet vent, in practice it will serve.
 

ScaredNewb69

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I will open up the floor in a second joist bay tonight and get a better sense of what else is connecting to the line upstream of the intended new location, in terms of vents and/or other fixtures, and add that info here.
 

ScaredNewb69

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IMO, a mechanical vent in the toilet arm would not add much if any performance. The toilet needs air to get out of the way IMO. Others may have other opinions, and they may be more correct than mine.

While the laundry vent is officially not allowed to serve as a wet vent, in practice it will serve.
Ah this is great context. It would also explain potentially why the laundry room is sometimes randomly a bit stinky lol (Don't get me wrong, I'm not a fan of the situation at all, but I'm also aware that with a
mobile home I have to work with what I've got)
 
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Reach4

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Does the laundry standpipe have a vent thru the roof? Those are better because they can relieve positive pressure.
 

ScaredNewb69

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Does the laundry standpipe have a vent thru the roof? Those are better because they can relieve positive pressure.
That's a great question. I'm not sure. Unfortunately all the plumbing is hidden under the floor, but above the 'belly', (combo rodent/moisture barrier +insulation). So it's quite hard to see what's there except where I open the floor. But I will look for a roof penetration above the laundry. If it does, would that satisfy the requirement for a vent on the trap arm?

(By the way, I'm operating under the assumption that the 'trap arm' is the extension between the main drain line and the sani bend below the WC flange)
 
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Reach4

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It would not satisfy Washington state code for houses. Rules for house trailers are different, and I don't know what those rules are.
 

John Gayewski

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So first you say it works fine, then you say it's stinky in the laundry room sometimes which indicates it doesn't work fine. You are answering your own question, you need some venting up grades.

A lot of people try to get away without vents and sometimes it can work. But we don't design systems or give advice that won't work consistently. Either add the vent or don't, but your really only gonna get advise that will work. Not many people are going to guess that something might work and tell you to do it.
 

ScaredNewb69

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So first you say it works fine, then you say it's stinky in the laundry room sometimes which indicates it doesn't work fine. You are answering your own question, you need some venting up grades.

A lot of people try to get away without vents and sometimes it can work. But we don't design systems or give advice that won't work consistently. Either add the vent or don't, but your really only gonna get advise that will work. Not many people are going to guess that something might work and tell you to do it.
I get where you are coming from and I appreciate the spirit of your advice, but the binary you are proposing - it either 'works' or 'doesn't work' - doesn't actually exist in reality. It certainly doesn't exist in mine.

The system as it exists 'works fine.' It doesn't work perfectly, or even as well as I'd like, in an ideal world. But the doodoo goes away when we flush, and after a year the only downside is that maybe once every other month you can detect a faint odor in the laundry room. It's never detectable beyond the laundry room, and it always dissipates on its own within an hour or two. In other words, it works perfectly well enough.

If you think I'm going to tear open the walls and ceiling of the doublewide I share with my wife and two kids to remedy that minor of an issue - to bring the system past the point of working perfectly well enough, to the point of working perfectly - well, that's a nice idea, but again, it doesn't conform to the reality that most people are living in, and certainly not to mine. If it did I'd be hiring somebody with standards as high as yours, rather than contenting myself with posting on a forum and doing the best I can on my own.

Personally, even if I don't move the toilet I'm going to (1) entirely replace the compromised particleboard subfloor around the WC with an exposure-rated OSB, with support framing/blocking to code, (2) replace the existing straight tee with a sani elbow, and (3) replace the loose, through-the-floor supply shutoff with a proper wall stubout. The system will be better for the changes I make, but it will not be perfect. I'm okay with that!

What I'm trying to do here is understand the parameters of the components I'm working with, so that I can understand where I can safely and wisely consider a compromise, and where I can't. If the bounds of safety or common sense eliminate the possibility of doing what I want to do, I won't do it. But personally I reject the idea that anything shy of perfect is not worth doing, even if it's an overall improvement.
 

John Gayewski

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I get where you are coming from and I appreciate the spirit of your advice, but the binary you are proposing - it either 'works' or 'doesn't work' - doesn't actually exist in reality. It certainly doesn't exist in mine.

The system as it exists 'works fine.' It doesn't work perfectly, or even as well as I'd like, in an ideal world. But the doodoo goes away when we flush, and after a year the only downside is that maybe once every other month you can detect a faint odor in the laundry room. It's never detectable beyond the laundry room, and it always dissipates on its own within an hour or two. In other words, it works perfectly well enough.

If you think I'm going to tear open the walls and ceiling of the doublewide I share with my wife and two kids to remedy that minor of an issue - to bring the system past the point of working perfectly well enough, to the point of working perfectly - well, that's a nice idea, but again, it doesn't conform to the reality that most people are living in, and certainly not to mine. If it did I'd be hiring somebody with standards as high as yours, rather than contenting myself with posting on a forum and doing the best I can on my own.

Personally, even if I don't move the toilet I'm going to (1) entirely replace the compromised particleboard subfloor around the WC with an exposure-rated OSB, with support framing/blocking to code, (2) replace the existing straight tee with a sani elbow, and (3) replace the loose, through-the-floor supply shutoff with a proper wall stubout. The system will be better for the changes I make, but it will not be perfect. I'm okay with that!

What I'm trying to do here is understand the parameters of the components I'm working with, so that I can understand where I can safely and wisely consider a compromise, and where I can't. If the bounds of safety or common sense eliminate the possibility of doing what I want to do, I won't do it. But personally I reject the idea that anything shy of perfect is not worth doing, even if it's an overall improvement.
Sewer gas isn't healthy. If you live with kids and a wife their health would be worth more than removing some drywall.
 
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