Bathroom Drain Lines

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So, as I understand it, this bathroom exists as is, and was installed without vents for the shower and the sink. And according to your drawing, the vent is actually running up the inside of the bathroom. You don't show the actual piping runs, so I am assuming they run relatively straight from the P-traps to the stack. If they were shown on the original post, I don't remember them. And you don't indicate if the existing piping is readily accessible from below. But assuming you do have access to the shower drain piping, you may be able to vent the exiting line by installing a sanitee in the horizontal line at no less than a 45 degree off vertical and run the vent inside the existing wall that the door opens against. You could then tie into the existing stack in the attic, again assuming there is an attic above this bathroom.

If the existing piping does not allow the vent to be installed as described above, you should be able to revise the existing drain piping with a small jog so that it runs directly beneath that wall and then the vent piping can be installed up that wall as described above.

A similar modification could be performed for the sink drain venting, but with a different wall. Now if the walls around the pedestal sink are exterior walls with little or minimal access in the attic, you could use an AAV (Air Admittance Valve) in the wall. It would need to be installed in a box open to the bathroom. I dislike those, but that may be your best solution for the pedestal sink.

An AAV possibly could be used for the shower vent with the existing piping if there at least 4" above the P-trap to allow for proper installation. Again, I dislike those, but that could possibly be a solution for the shower vent with minimal work. Assuming there is a basement with adequately sized floor joist, see my sketch below.

1640631697097.png1640634191930.png
 
MicEd69 said:
So, as I understand it, this bathroom exists as is, and was installed without vents for the shower and the sink. And according to your drawing, the vent is actually running up the inside of the bathroom. You don't show the actual piping runs, so I am assuming they run relatively straight from the P-traps to the stack. If they were shown on the original post, I don't remember them. And you don't indicate if the existing piping is readily accessible from below. But assuming you do have access to the shower drain piping, you may be able to vent the exiting line by installing a sanitee in the horizontal line at no less than a 45 degree off vertical and run the vent inside the existing wall that the door opens against. You could then tie into the existing stack in the attic, again assuming there is an attic above this bathroom.

If the existing piping does not allow the vent to be installed as described above, you should be able to revise the existing drain piping with a small jog so that it runs directly beneath that wall and then the vent piping can be installed up that wall as described above.

A similar modification could be performed for the sink drain venting, but with a different wall. Now if the walls around the pedestal sink are exterior walls with little or minimal access in the attic, you could use an AAV (Air Admittance Valve) in the wall. It would need to be installed in a box open to the bathroom. I dislike those, but that may be your best solution for the pedestal sink.

An AAV possibly could be used for the shower vent with the existing piping if there at least 4" above the P-trap to allow for proper installation. Again, I dislike those, but that could possibly be a solution for the shower vent with minimal work. Assuming there is a basement with adequately sized floor joist, see my sketch below.

View attachment 32852View attachment 32853
Click to expand...
 
MicEd69,

Thank you for helping with working through this.

The images have been updated from the original post.

1) The home was built in the 40s, so no vents were installed for the shower or sink.
There is no room around the existing shower area to run a vents in the walls.

NOTE: It is possible to pack out the studs in the shower area to run a vent if that is the only way to make this work.
Prefer not to lose any of the shower foot print area.

2) There is an attic above this area and it is a second floor bathroom. So tie into the main vent is possible.

3) The room is demoed down to the studs and the floor has been removed, so the joist bays are open.

4) The new PVC drains will run parallel to the floor joist.
Existing construction allows the drain lines to run past the ends of the floor joist, then turn to pick up the soil stack.

I thought possible intergrating a wet vent system would make this work.
 
Well, the vent at the end of the lavatory run is great for the lavatory, but you still need a vent for the shower within 6 feet of the shower P-trap to meet the IPC requirements. And note that the AHJ (Authority Having Jurisdiction) inspector can apply more stringent requirements as to that length even is 6 feet is black and white shown in the IPC. We have such an "authoritarian" inspector “legislating from the bench” in a neighboring community. They are the ones who issue the "passed" inspection reports, so what they say goes. Even if you want to go to their boss to try to overrule them, it rarely is successful and usually just causes more issues. You don't need to get into a pissing contest with a skunk; you won't win.

Not knowing what is under the bathroom, would there be any way to drop that 6' 6" shower drain line, which means the 3" line you refer to as a "wet vent" would also have to drop, and be able to install an AAV between the floor joists? That 3" line can be downsized to 2" as well. The AAV would need to be framed and open in the first-floor ceiling. So, if there was a closet there, that would work. If the drain line was not in a closet, you might be able to box in the drain line such that a "beamed ceiling look" would hide it. The AAV would still need to be open and accessible, but you could put a colored screen to cover the opening that would hide it somewhat. Just a thought if that would work into your motif. If none of this is possible, then I'm thinking you will have to sacrifice some shower space and tie into the vent in the attic. You only need a 1 1/4" vent instead of a 1 1/2", and a 1/4" is a 1/4" you know.

I hope this gives you some ideas. I'm not sure pictures would help provide any more feedback but send them of the existing installation if you want. They may provide more insight and possibly other options.

Good Luck.
 
Though I had hoped not to lose any of the shower foot print,
it appears that is the best resolution for proper venting.
 

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Yes, I think that's what has to happen. Just make sure a few more things:

1. The wye shower vent has to be at least 2 pipe diameters from the P-trap, 4" here.
2. The "horizontal" vent run between the two 1 1/4" vents needs to at least 1 1/2".
3. I'm assuming the "horizontal" vent run will be in the attic. If not, it at least needs to be above the top of the pedestal sink.
4. The "horizontal" vent runs need to slope towards the drain piping at 1/4" per foot.

Good luck and happy plumbing.
 
MicEd69 said:
Yes, I think that's what has to happen. Just make sure a few more things:

1. The wye shower vent has to be at least 2 pipe diameters from the P-trap, 4" here.
2. The "horizontal" vent run between the two 1 1/4" vents needs to at least 1 1/2".
3. I'm assuming the "horizontal" vent run will be in the attic. If not, it at least needs to be above the top of the pedestal sink.
4. The "horizontal" vent runs need to slope towards the drain piping at 1/4" per foot.

Good luck and happy plumbing.
Click to expand...
Framing - After another look at the framing there are two options:
1) See Diagram A
The studs need to be packed out 2". So there would be a lose of the shower foot print.

2) See Diagram B
Bore through the joist and tie into the vent for the sink.
NOTE: Follow guide lines for boring & notching joist.

The rise from the shower drain line to the line for the vent
may only be couple of inches till the vertical rise in the wall.
 

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  • Master Bathrom 12-28-21 Plan View - Diagram A.jpg
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  • Master Bathrom 12-28-21 Plan View - Diagram B.jpg
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Yep, that looks like a great plan. Assuming they are 2x8 joists, you should be good to go that route. I've done that a couple of times. Once I had to go through four joists which required multiple pieces of pipe and couplings, but it worked quite well and maintained basement headroom.

If the joists are 2x6, you may still be able to do this if you use 1 1/4" copper pipe and have room for the 1 1/4" copper to 1 1/2" PVC adapter. You are limited to 1 1/2" holes in a 2x6.
 
PrecisionPlum said:
Framing - After another look at the framing there are two options:
1) See Diagram A
The studs need to be packed out 2". So there would be a lose of the shower foot print.

2) See Diagram B
Bore through the joist and tie into the vent for the sink.
NOTE: Follow guide lines for boring & notching joist.

The rise from the shower drain line to the line for the vent
may only be couple of inches till the vertical rise in the wall.
Click to expand...

The lavatory still isn’t vented.
 
MicEd69 said:
Yep, that looks like a great plan. Assuming they are 2x8 joists, you should be good to go that route. I've done that a couple of times. Once I had to go through four joists which required multiple pieces of pipe and couplings, but it worked quite well and maintained basement headroom.

If the joists are 2x6, you may still be able to do this if you use 1 1/4" copper pipe and have room for the 1 1/4" copper to 1 1/2" PVC adapter. You are limited to 1 1/2" holes in a 2x6.
Click to expand...
The joist are 2x10

Please see the attached.
I want to do Diagram A if possible.
 

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  • Master Bathrom 12-29-21 Drain Layout - Diagram A.jpg
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  • Master Bathrom 12-29-21 Drain Layout - Diagram B.jpg
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Yep, Twowaxhack is correct, B is required, the sink needs to vented. I was wrong earlier when I said it was vented by the vent at the end of the lavatory run. Wasn't pay attention. And I can't remember if you said this was a pedestal sink or not. If it isn't, you could use drawing A with the addition of an AAV under the sink as indicated in the picture in one of my earlier posts. I don't think there would be room under a pedestal sink to install an AAV. Hope this helps.
 
MicEd69 said:
Yep, Twowaxhack is correct, B is required, the sink needs to vented. I was wrong earlier when I said it was vented by the vent at the end of the lavatory run. Wasn't pay attention. And I can't remember if you said this was a pedestal sink or not. If it isn't, you could use drawing A with the addition of an AAV under the sink as indicated in the picture in one of my earlier posts. I don't think there would be room under a pedestal sink to install an AAV. Hope this helps.
Click to expand...
Pedestal sink is being used.
 
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