I am adding a new bathroom and was looking for help on the plumbing layout. I have reparied plumbing many times, but never ran all new so I want to make sure I connect everything properly and in the correct order.

I can add more images if these dont tell enough of the story.

I have a room underneath that I know I will have to do some ceiling work for pipes that have to run under the joists, but I am trying to keep that at a bare minimum if possible.

In my head I will have to 90 out of the stack with a wye under the joists and 90 up for the toilet (3" ). I thought I could add another wye (2" out) in the stack above or below (unsure) to run right next to the toilet 3" stack horizontally below the joist as well, but then 90 up into the joist bay asap and then run horizontal with the joist to the shower. If there is a better spot to do this I am open. I am not positive where in the stack I can pull for the sink...does it need to be above or below the toilet tee. Then venting the shower and sink. I imagine the sink will be easy. I was wondering if I could put a wye right after I 90 to go horizontal in the joists for the vent and since I cant go straight up run at a steep 45 angle to get just above the first joist. I may have to do a slight floor/wall modification to accomplish that, but its not a big deal if that is how I have to vent it. I dont believe I can go horizontal through the joists for the vent so thats why I thought of the 45 way even if I have to modify the floor in the room. I beleive doing a vent is always the best way, but if I its smarter to do it without a vent properly I am open as well.

Just to calify the main stack is 4" to center of pipe behind the bathroom wall. It will be boxed in later as its in a closet area, but that was the best place to bring the pipe up from the basement as its in a void where (2) 8" HVAC runs go up and has plenty of room to add the 3" drain all the way to the roof.

This bathroom is on the second floor.

Feel free to offer any suggestions. If my thoughts are way off I apologize in advance.






Thanks

What is that existing stack being used for? If it's a vent for lower fixtures, you can't use it as a drain pipe.
You can arrange the new drains to the suitable stack like this drawing.

It will be a completely new stack I am putting in. It will connect to the main septic line in the basement. I did already confirm I am ok to add a full bath to this loaction on the main.

I was ust concerend with vents and/or the proper way to connect the shower and sink. I saw that drawing as well, but then found contradicting info that the toilet and shower can tie in together at the same spot. I just want to make sure I am up to code as I had to pull a permit for this work.

This tee has the branches not opposing to each other and at different centerlines, so you should be good to go.

Don't you need sanitary tees?

Those are a form of a sanitary tee.

I think I made it somewhere now. Give me your thoughts please.

Option 1 goes under the joists for the toilet and above a 2x8 (actually 7" and through a 2x12 (actually 11". I know these are @#$%& sizes. I am allowed to notch the 2x8 1-1/16" max. If I go down 2" on the 2x12 and put a 3" hole I can run the 2" drain over the notche 2x8 and through the 2x12. Then I dont have to go through the ceiling for the shower.




Option 2 goes under all the joist with the toilet and the shower.




I am hoping these are good code passing layouts. I prefer option 1 unless anyone has an objection.



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What purpose is the 2x8 serving? What is the wall above the 2x12s supporting? A 2x12 can have a 3 5/8" diameter hole drill through it and this is big enough for a 3 in pipe. The 2-in pipe could also be drilled through the 2x12 and 2x8. Blocking could be installed between the 2x12s and the 2x8 to reinforce the areas that were drilled. If the wall is supporting a heavy load above, seak approval from an engineer for drilling the 3 5/8 hole. There's going to be a minimum distance between the holes for the 3-inch and 2-in pipe of 7 1/4 in. This can keep all your drain piping above the ceiling level.



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There are two questions, I am not a pro so take my comments with a grain of salt.



(A) I don't know what code you are under, but I have ran into this once before where I am. That section below the lav trap arm is a wet vent for the toilet. I had one inspector who insisted that this section cannot be reduced in size because it's a wet vent and asked me to keep the same size as the main drain and not reduce it's size until above the lav's sanitary tee. I didn't fight him and just did it because it was easy to do.

( Is that a cleanout? If it's a drain inlet for an upstair fixture this could be a problem.

It is a cleanout at the top. Its only there because the county requires a test that they need to do where a balloon needs to be able to be inserted to shut it off and its easier than getting on the roof. I may even leave it disconnected for the test if I can instead of putting the cleanout in there at all.

I actually had an inspector tell me to reduce the 3" to 2" aboe the water clost as it turns out the county does a free consultation. So I am hoping thats correct or he is the same inpector that come back out

The 2x8 is spanning walls. It has a closet area above it and finished space below it. I am sistering it with a 2x12 as there will be a step down right there. That is why I can't bring the water closet through that area and it will be below the joists. The 2x12 will be sitting on a load bearing wall going in same direction. Plus I am only cutting a hole through it for the 2" pipe now.

I think I am good, but the 2" reducing above the water closet has me thinking.

From 2024 Ohio plumbing code. The lavatory sink is 1 DFU. Chart allows a 2" wet vent.







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steve, I noticed at the top the vent pipe size increases again, isn't there code governing pipe size decreases and increases as it goes downstream or vents are exceptions? I know some AHJs prohibits a section of pipe that has a reduced diameter. I guess I e concern is if future service tries to run a full size snake cutter down the roof vent it will stop at the 2".



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Some areas require a larger vent pipe at roof penetration(and some distance below roof) for frost closure protection.

Is it typical to snake from the roof in other states?

In FL it is very common most would prefer to haul the machine onto the roof to run a snake vs to go inside to pull a toilet and splash dirty water onto the bathroom floor and walls as the snake works. I have one property where the vent made a kink in the shallow attic and a full size snake cutter can't make it through so always had trouble snaking it from there.

That is just as he mentioned. We have to go throug the roof with 3" in Ohio. It is very rare to goto a roof here to snake anything. To be honest, I don't think I have ever needing anything snaked since I was a kid 40 years ago though.