New Bathroom Venting Question

[RJC]

Hey, new poster here. I'm remodeling an old house and redid the plumbing in one bathroom and the kitchen a couple years ago with the advice from a professional plumber who is a friend of a friend. Now I'm on to adding a second bathroom and was wondering if there are any issues with the DWV layout I am considering. I'm not the best at these kinds of drawings, but the attached shows what I am thinking. The constraints that I am working with are 1) the existing three inch drain comes into the room from the crawl space in the right corner of the picture, and the crawl space in the area immediately downstream is hard to access (the crawl space is super shallow generally), 2) the tub and toilet locations are both really close to where the drain enters the room (the tub and toilet drains in the picture are <3ft apart), making it tricky to fit everything in, and 3) the lav is about 10 feet away from the shower on the far left of the picture (its a very long narrow room).

I understand that my toilet in my layout is technically being wet vented through the lav (and that the lav vent is 1.5" vs. 2" you would normally want to wet vent a toilet), but I'm hoping this is okay since the shower has a 2" vent and is immediately upstream. I'd really appreciate anyone's thoughts/comments.

One other consideration: There is a washing machine drain that ties into this waste line about 5 feet downstream from all of this, and when I was in the crawl space recently I noticed that it is trapped in the crawl and not vented. We haven't had any problems with siphoning from the trap thus far (probably because to date the washing machine has been the last fixture in the system and everything else is vented well), but I know I will need to correct it eventually. However, if there is anything I can do with respect to the bathroom I am now adding in order to minimize complications with the laundry drain, such as going a bit overkill on making sure it is well vented, I'd like to do it.

Thanks again for any help anyone can provide.

 

[RJC]

Hey, new poster here. I'm remodeling an old house and redid the plumbing in one bathroom and the kitchen a couple years ago with the advice from a professional plumber who is a friend of a friend. Now I'm on to adding a second bathroom and was wondering if there are any issues with the DWV layout I am considering. I'm not the best at these kinds of drawings, but the attached shows what I am thinking. The constraints that I am working with are 1) the existing three inch drain comes into the room from the crawl space in the right corner of the picture, and the crawl space in the area immediately downstream is hard to access (the crawl space is super shallow generally), 2) the tub and toilet locations are both really close to where the drain enters the room (the tub and toilet drains in the picture are <3ft apart), making it tricky to fit everything in, and 3) the lav is about 10 feet away from the shower on the far left of the picture (its a very long narrow room).

I understand that my toilet in my layout is technically being wet vented through the lav (and that the lav vent is 1.5" vs. 2" you would normally want to wet vent a toilet), but I'm hoping this is okay since the shower has a 2" vent and is immediately upstream. I'd really appreciate anyone's thoughts/comments.

One other consideration: There is a washing machine drain that ties into this waste line about 5 feet downstream from all of this, and when I was in the crawl space recently I noticed that it is trapped in the crawl and not vented. We haven't had any problems with siphoning from the trap thus far (probably because to date the washing machine has been the last fixture in the system and everything else is vented well), but I know I will need to correct it eventually. However, if there is anything I can do with respect to the bathroom I am now adding in order to minimize complications with the laundry drain, such as going a bit overkill on making sure it is well vented, I'd like to do it.

Thanks again for any help anyone can provide.

Would really appreciate any advice, even if it's "you are way off base and need to get some help."

I did notice that I also have a short horizontal section on my vent coming off the tub, which I think may not be allowed? If that's right, I could tweak it to remove the need for the vent to run horizontally to the wall.

 

[Sponsor]

 

[Terry]

If you could get rid of the horizontal on the tub vent that would be nice. If you are wet venting the toilet with the tub or the lav, they should be 2".

 

[RJC]

Awesome, thanks so much for the input. Just to make sure I understand: I guess I am went venting the toilet through the tub, which has a 2" vent, and the drain line is at least 2" all the way from the tub to the toilet. However, the lav drain line also ties into that line between the shower and the toilet. So does the lav drain line need to be 2" all the way to the lav and up to where the lav vent connects to the 2" vent as well?

 

[Terry]

Something has to be 2"
Either the lav or the tub.