Combining vents. Multiple fixtures in one roof vent.

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schafphoto

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Jan 31, 2021
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Location
california
I'd like to get advice on a plumbing rehab in an old house with back to back bathrooms and laundry. There is a 1.5 inch and a 2 inch vent leaving the house. The clay pipe to the street sewer out in the yard is 3", but the ABS inside is 4" and must transition at some point underground before I owned the house. This has not been a problem.

I'd love to add a second bath without adding another 2" vent through the roof but I'm pretty sure I'm going to need to add one 2 inch (orange) vent above bathroom 2. The shower #2 is closer to the original 2 inch vent (blue) and I'd like to use that. I'd like to use the blue vent for the Washer and a utility sink too on the same wall as the bathroom. Any advice would be appreciated.
I fall under the California Plumbing code based on UPC (2019).

vent plan 2021.jpg
 
I’m not going to entertain anyone’s code but what you have drawn will perform safely.

I would have at least one 3” vent in the system.

I would replace the sewer.

Good luck sir. 👍
 
The blue vent has probably exceeded its fixture unit load. That said, it’ll work.
 
When I revent I try not to do it in the wall. I like to tie them together in the attic, not the wall. This allows me access to each vent later if I want.
However on a large job this would cost $.....

Also with floors above you can’t access the attic for reverting so it’s done like you’ve drawn in the wall.

just making conversation.....
 
I have the ability to do it in the attic... but I did not think of that as an advantage, but not drilling 1.5 inch holes in the studs might be a real benefit...
 

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