Drain Pipe Rats Nest

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Owen

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Hi Everyone,
My wife and I are working on an unfinished basement bathroom project. I have a drain issues that I need some brainstorming about. It is an upstairs shower drain that is the issue. The major problem is that when it was installed, it sticks out past the joist so we want to configure it so it is within the joist wall structure. I can move all the water pipes, that is no problem. I just don't know what to do about the drain.

There are two vent pipes that go into the next room, a utility room with washer dryer and water heater. So I could move those in some way if that needs to be done.

Any suggestions? Are there better pictures needed?

Thanks,
Owen

Drain Pipes Floor to ceiling with line.jpg
 

wwhitney

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Looks the indicated trap has no vent. What is coming into the top entry of the combo just downstream of the trap? Hopefully you'll be able to raise the trap, provide a vent, and still pick up the other drain currently coming into that combo.

Cheers, Wayne
 

Owen

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I have some new pictures that might show the problem a little better.

One picture shows the venting of the shower drain. The drain that sticks down by the log, is the shower drain that needs to be moved up because the bottom of the log is going to be my ceiling. The red arrow points to the venting. The log is 9.5 inches in diameter. Also that drain needs to be within the wall. How little drop can I get away with?

Second picture shows how far the shower drain sticks out past the joist.

I might be able to swivel that p trap into the wall so it is not sticking out and then come across to connect to the down pipe, but I have a joist in the way. And also there is another pipe vent that is in the way. How do I manage that?

Third picture shows the room the we want to remodel.
 

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Owen

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The p-trap should be installed into a santee on the vertical there, not a combo or wye. How is that vented?


Ok, I think I understand. New picture of what I think you mean. Remove the current line that goes to wye. New line comes down from shower to ptrap, then horizontal to a 90 down to another 90 that goes to santee. Vent is top of santee .

Does that work?
 

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wwhitney

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No, the san-tee has to be connect to the horizontal pipe exiting the p-trap (the trap arm). Every trap needs a vent, and that vent has to connect to the trap arm before it falls more than one internal pipe diameter.

If the pipe entering the wall, the one pointed to by the red arrow in your second photo, is a dry vent for the shower, then that's a problem. A dry vent needs to stay vertical (at most 45 degrees off plumb) until it reaches 6" above the flood rim of the fixture.

If instead that pipe happens to be the drain from a dry vented lavatory, then it can be used to wet vent the shower. [In which case the geometry required may be a little different than what has been discussed.]

Cheers, Wayne
 

Owen

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No, the san-tee has to be connect to the horizontal pipe exiting the p-trap (the trap arm). Every trap needs a vent, and that vent has to connect to the trap arm before it falls more than one internal pipe diameter.

If the pipe entering the wall, the one pointed to by the red arrow in your second photo, is a dry vent for the shower, then that's a problem. A dry vent needs to stay vertical (at most 45 degrees off plumb) until it reaches 6" above the flood rim of the fixture.

If instead that pipe happens to be the drain from a dry vented lavatory, then it can be used to wet vent the shower. [In which case the geometry required may be a little different than what has been discussed.

Cheers, Wayne

The pipe entering the wall, the one with the red arrow is a dry vent for the shower. It goes horizontal into the adjacent utility room and then goes vertical to the roof. It goes up through the wall of the shower upstairs.

Well, I really don't know how to fix this issue.
 

wwhitney

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So what is the horizontal relationship between the vent riser in the utility room, and the p-trap inlet (shower drain)? Preferably as two dimensions, one perpendicular to the stud wall, and one perpendicular to the foundation/log wall. If there are no horizontal bends in the utility room, the latter looks to be around 25" assuming the studs are 16" on center.

If you have available space and access to the DWV in the ceiling of the utility room, one solution would be to raise the p-trap and reorient it's outlet to the side inlet of a san-tee directly under the vent riser; then the bottom outlet of the san-tee would immediately hit a LT 90 to come back into the room pictured to connect up to the drain that the combo currently connects to.

Cheers, Wayne
 

Owen

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So what is the horizontal relationship between the vent riser in the utility room, and the p-trap inlet (shower drain)? Preferably as two dimensions, one perpendicular to the stud wall, and one perpendicular to the foundation/log wall. If there are no horizontal bends in the utility room, the latter looks to be around 25" assuming the studs are 16" on center.

If you have available space and access to the DWV in the ceiling of the utility room, one solution would be to raise the p-trap and reorient it's outlet to the side inlet of a san-tee directly under the vent riser; then the bottom outlet of the san-tee would immediately hit a LT 90 to come back into the room pictured to connect up to the drain that the combo currently connects to.

Cheers, Wayne


The vent pipe that goes in the the utility room is 26" and the goes vertical up through the upstairs bathroom wall. Top edge of the ptrap is 13 inches from ceiling. THe bottom of vent pipe is 7 inches from ceiling. The vent gets reduced out of the wye down to 1.5".

Isometric06272021.jpg
Piping View.JPG
Utility Room Venting Pipe.JPG
 

wwhitney

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Thanks for the isometric. I suggest something along the following lines, where I marked up your drawing (blue is 2", red is 1-1/2"). And here's a textual description, as I'm not sure I rendered the angles properly on your not to scale isometric:

Raise the trap arm so that the outlet is above the two pipes that currently go through the drywall (and above your desired ceiling level) and turn the outlet to be parallel to the foundation wall. Looks like you would then be able to go through the drywall and just miss that stud. Continue with the 2" trap arm on that line until a "flat" (2% slope at inlet and outlet) 45 will point the trap arm at the current vent riser. Where they intersect, use a 2x1-1/2x2 sanitary tee (may need to use a 2" sanitary tee with a bushing in the top entry). Out of the bottom of the 2" sanitary tee, use a LT90 (can be street if you want to minimize elevation loss) to go back horizontal parallel to the foundation wall to penetrate the drywall again. Then a regular quarter bend to turn vertical and line up with the drain that is currently the bottom of the (to be removed) combo.

The particular geometry of how you get from the trap outlet to the new sanitary tee in the other room doesn't matter, just that the total fall of the trap arm is no more than 2", and the length is no more than 5' (UPC requirement in WA), and fewer bends is better. So if you can get the angle right, you could just point the trap outlet directly at the vent riser and have no elbows in the trap arm.

Cheers, Wayne


Isometric06272021Modified.jpg
 
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Owen

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Thanks for the isometric. I suggest something along the following lines, where I marked up your drawing (blue is 2", red is 1-1/2"). And here's a textual description, as I'm not sure I rendered the angles properly on your not to scale isometric:

Raise the trap arm so that the outlet is above the two pipes that currently go through the drywall (and above your desired ceiling level) and turn the outlet to be parallel to the foundation wall. Looks like you would then be able to go through the drywall and just miss that stud. Continue with the 2" trap arm on that line until a "flat" (2% slope at inlet and outlet) 45 will point the trap arm at the current vent riser. Where they intersect, use a 2x1-1/2x2 sanitary tee (may need to use a 2" sanitary tee with a bushing in the top entry). Out of the bottom of the 2" sanitary tee, use a LT90 (can be street if you want to minimize elevation loss) to go back horizontal parallel to the foundation wall to penetrate the drywall again. Then a regular quarter bend to turn vertical and line up with the drain that is currently the bottom of the (to be removed) combo).

The particular geometry of how you get from the trap outlet to the new sanitary tee in the other room doesn't matter, just that the total fall of the trap arm is no more than 2", and the length is no more than 5' (UPC requirement in WA), and fewer bends is better. So if you can get the angle right, you could just point the trap outlet directly at the vent riser and have no elbows in the trap arm.

Cheers, Wayne


View attachment 74834


Wayne,
That looks like a plan, thank you. I am going to try to implement this. May have more questions, but for now this will keep me busy.
Thanks,
Owen
 

Owen

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Hello all and Happy Holidays,
We got our drain and vent plumbing all completed thanks to Wayne and his recommendations and we are now to the next phase of our project.

I have purchased my rough in valves for the shower and for the tub. See picture where I am going to put them.

When I put those in place I can redo all the copper with PEX, much of the 3/4 inch stuff is too low for our proposed ceiling. I have watched enough PEX videos to feel pretty confident about doing this. I did relocate a water heater prior to this project and did a bunch of copper/soldering, so the PEX seems to be a little easier.

To place the rough in valves at the proper depth I need to know wall thickness. I have been reading various books, mostly dated material, that has many suggestions; from doing a complete wall mud job to CBU to this stuff called Kerdi. My head is swimming.

As far as I can conclude these would be the steps for the bathroom.

1. Shower pan - it is over concrete, I am planning on the deck mud technique, 1/4 rise per foot.
Questions - Thickness at the drain should be 3/4"?
2. Walls install now, CBU or some other product? I did read somewhere that there is a better product than CBU. Any suggestions?
And a plastic vapor barrier between wall and studs?
3. Then a PVC pan liner? Instead of the PVC, I could use the Kerdi? Kerdi then would be applied to walls also. If I do the PVC, then not sure about the walls, maybe just the sealer?
4. Then a couple coats of some kind of sealer, any suggestions?
5. Tile.

So, my wall thickness would be, wall product + Kerdi + Tile thickness.

Your comments and suggestions are greatly appreciated.

Owen

Roughin.JPG
 
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Owen

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Still working on my bathroom project. I am ready to tackle the water pipes. Much of the pipes are too low for the ceiling or are sticking out past the joists, so they need to be redone, either copper or PEX.

My system consists of a a main 3/4 inch copper for hot and cold and then it branches then to 1/2 inch. For instance it branches to 1/2 for sink and washer dryer in utility room, or branches to 1/2 for sink and toiled in the room that I am working on. It also has some branches to 1/2 for the toilet upstairs and also to the kitchen sink upstairs. Water comes into the house an adjacent room. It's probably pretty typical.

I am thinking about replacing the copper with PEX. Do I need to replace the 3/4 copper with 1" PEX and the 1/2 inch with 3/4 PEX? Or would it be feasible to just use 3/4 for all the PEX runs and then connect to existing 1/2 copper? Any thoughts?
 
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Terry

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A two bathroom home should have 1" coming in. If you're using PEX, then it should be 1" where it begins.
1/2" PEX works for two plumbing fixtures. The washer and sink can be 1/2"
For a bathroom, up to two with 1/2", that would be a tub and a lav. If you adding the toilet, then either bump to 3/4" or give the toilet it's own 1/2" line.

screaming-in-shower.jpg
 
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