DIY Master Bathroom retrofit plumbing & vent stack

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dannyj25

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Hi All - new to the page and this site is fantastic! Thank you to everyone for your help and guidance.

I'm remodelling my master bathroom on the 2nd floor of my house and when I had demo'd everything came across what looks like a wild setup. There was a shower / pony wall combo and then alcove tub with center drain. Then there is the botch job 3" vent stack that emerges from the top of the 3" main line with a 3" x 3" x 2" wye. That vent stack penetrates through the roof after some twists and turns and has been leaking for years apparently.
Existing bathroom.jpg
My problem now is I purchased a left drain alcove tub, will rebuild the pony wall but now the crazy vent stack is in the way of the new tub overflow and drain line. The water lines are also in the way but can be easily moved.

Since there is not space in the floor joist bay to add the vent stack wye and a 90 turn to the bath drain p-trap I was thinking to do the following:

Proposed layout.jpg
Bathroom proposed small .jpg
1. Redirect the vent stack by laying the 3"x3"x2" wye on its side so the vent moves horizontally under the floor to the exterior wall and then transitions vertical to move up through the roof to get it out of the way.

2. Add 2x 90 turns to the new bath drain line, cut a new 2" hole in the floor joist so this drain line can form a U and tie back into the 3"x3"x2" wye that will be on its side.

Also, could I change the 3" vent for a 2" vent pipe. We are in Charlotte, NC.

I'm new to all of this so just trying to figure out the best solution to what seems to be an impossible problem.

Any and all suggestions welcome or theres probably a much better way than what I've though about.

Thanks so much.
 

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Hi, is that 3" stack the main vent/soil stack? Does that plumbing run into another 3"or 4" vertical vent stack? Of that is the main vent stack and your already on the second floor, it would need to remain 3". Look up what your area follows for codes. UPC or other. That 3"x3"x2" sanitary tee needs to become a 3x3x3 wye. You can then reduce the continuous run to the shower to 2" or keep it 3" if you have the space for a 3" trap. Make sure that your drain piping (wet venting) is sloping properly. Depending on pipe size and or distances, it's 1/8" or 1/4" slope. Use a bubble level to figure out your slope. Only use clear cleaner or primer. Purple is OK for drain pipe but not potable water pipe. It's just better to make a habit of not using purple primer anymore. Use the medium blue cement.
 
Hi, is that 3" stack the main vent/soil stack? Does that plumbing run into another 3"or 4" vertical vent stack? Of that is the main vent stack and your already on the second floor, it would need to remain 3". Look up what your area follows for codes. UPC or other. That 3"x3"x2" sanitary tee needs to become a 3x3x3 wye. You can then reduce the continuous run to the shower to 2" or keep it 3" if you have the space for a 3" trap. Make sure that your drain piping (wet venting) is sloping properly. Depending on pipe size and or distances, it's 1/8" or 1/4" slope. Use a bubble level to figure out your slope. Only use clear cleaner or primer. Purple is OK for drain pipe but not potable water pipe. It's just better to make a habit of not using purple primer anymore. Use the medium blue cement.
Thanks so much for your input. Yes, from what I can tell that is the main vent stack for the house. There are a couple of other small vents (1 1/2” through the roof that serve a second bathroom on the other end of the house and the double vanity sink I believe?).

Sorry, I’m new to the terminology and probably using the wrong terms. When you say the sanitary T needs to change to a 3x3x3 Wye are you referring to this one?:

8908B044-04BD-4EDE-BD27-DD3D1F5ECB76.jpeg

If I make that change would the bath drain pipe (marked in yellow) then become a 3” coming from that new 3x3x3 wye?

1887FF22-AE2B-44DD-B44F-8B0C582E6270.jpeg

When you say reducing the continuous run to the shower to 2” - is that this section marked in BLUE?

300C8278-3D79-4DE8-A1A4-437CCFDED08E.jpeg

Sorry for the novice questions, just want to make sure I’m understanding correctly.

Also, is it ok to put the new 3x3x3 wye fitting on its side so that the wye portion going off to vent through the roof starts off under the floor until it meets the exterior wall?

Like this:

4F0EB313-A8D7-4454-8FCD-80E73089F596.jpeg

Thanks so much
 
Last edited:
Thanks so much for your input. Yes, from what I can tell that is the main vent stack for the house. There are a couple of other small vents (1 1/2” through the roof that serve a second bathroom on the other end of the house and the double vanity sink I believe?).

Sorry, I’m new to the terminology and probably using the wrong terms. When you say the sanitary T needs to change to a 3x3x3 Wye are you referring to this one?:

View attachment 43717

If I make that change would the bath drain pipe (marked in yellow) then become a 3” coming from that new 3x3x3 wye?

View attachment 43718

When you say reducing the continuous run to the shower to 2” - is that this section marked in BLUE?

View attachment 43719

Sorry for the novice questions, just want to make sure I’m understanding correctly.

Also, is it ok to put the new 3x3x3 wye fitting on its side so that the wye portion going off to vent through the roof starts off under the floor until it meets the exterior wall?

Like this:

View attachment 43720

Thanks so much
 
Morning, I didn't see the fitting clearly that is feeding the vent. I was talking about the 2" section after the vent to the right. Past what you marked in light blue. That 3" x 3" x 2" fitting you have there now is ok. That is a 45⁰ long sweep reducing wye tee. That is acceptable 👌 and yes it can be turned down to run under the floor. Just make sure it isn't to flat. Still should have 1/4" slope up per ft working it's way under the floor to its eventual exit up through the roof. Do a Google search about wye tees and sanitary tees code and you will see what I was talking about before. Looks like everything is all glued together so in order to reuse fittings you will need to make sure you have enough pipe before and after the fittings to reglue to. Otherwise you will need to buy the fittings you need to complete this. Don't be afraid to buy steel banded clamps. I use them all the time in place of glued couplers. Makes life easier.
 
Morning, I didn't see the fitting clearly that is feeding the vent. I was talking about the 2" section after the vent to the right. Past what you marked in light blue. That 3" x 3" x 2" fitting you have there now is ok. That is a 45⁰ long sweep reducing wye tee. That is acceptable 👌 and yes it can be turned down to run under the floor. Just make sure it isn't to flat. Still should have 1/4" slope up per ft working it's way under the floor to its eventual exit up through the roof. Do a Google search about wye tees and sanitary tees code and you will see what I was talking about before. Looks like everything is all glued together so in order to reuse fittings you will need to make sure you have enough pipe before and after the fittings to reglue to. Otherwise you will need to buy the fittings you need to complete this. Don't be afraid to buy steel banded clamps. I use them all the time in place of glued couplers. Makes life easier.
Love it!! Thanks so much for the help. The space is definitely tight to glue a new fitting in there if I cut this current 3 x 3 x2 out but might try one of those pipe reaming bits to leave me some room. Not sure what you think of those - are they worth it? Thanks again. Really appreciate your help
 
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