Hi all! First post.

I'm looking into layouts for two bathrooms I would like to install in my house. I'd like some advice on venting.

I drew this diagram showing roughly what I am looking to do and would love to hear some input on the draining and venting. I think I have it mostly figured out but im not quite sure if this venting works or in particular what fittings I should be using at the 4 way at the stack on the second floor, or for venting the WC on the first floor. Hoping you guys can get me pointed in the right direction!

Thanks!

second floor looks fine.
first floor needs the shower vent tied into the lav vent.
you can not join the wc and shower vents unless the tee is 6 inched higher than the flood rim of the higher fixture.
so either bring the tee up higher or tie into the lav vent

Also, you do NOT want the upper toilet to fludh past the lower one's connection to the stack.

Oh that makes sense. There is a vaulted ceiling over where the lavatory is so I can't go across the ceiling. If im reading this right, I can just run the vent from the WC up parallel to the vent and tie in at a 4 way?

Like so?

hj, what would be the usual way around this?

if the lower toilet is vented, what's the problem?

I'm not really sure myself. But he's got me wondering if I would be better off going straight down from the WC on the first floor and going into the horizontal section instead of the vertical?

My only thought would be maybe the slug over water from the 2nd floor WC would be enough to overwhelm the vent on the 1st floor WC.

it is pretty technical but if you tie the second floor toilet into the horizontal that is below the first floor toilet...
the upper floor bathroom for the purpose of plumbing codes becomes the lower of the two AND the first floor bathroom becomes the top bathroom group. now plumbing venting changes accordingly.

If I'm reading you right, It would be more like this. What's the advantage?



Im open to being schooled for sure, it does seem like its a bit more tricky to fit into the space I'm working with but if that's the correct way to do it...

Edit: no I dont think that image is what you meant now that im looking at it again. I think I see what you mean. Still wondering if there is reason to do it that way. It avoids the slug from the 2nd floor WC issue. Id have to revisit the venting...

Edit 2: Do you mean something more like this? I can see an advantage flow wise for the WC's.





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!!!!! BEST PRACTICE !!!!!

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

if you showed a diagram of the layout of 2 bathroom groups stacked one ontop of the other to 10 different plumbers, you would get different piping/venting opinions.

the OP is VERY close to a 'hi-rise' vent stack design



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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

You guys are great thank you for all the input. Taking what I have learned so far and looking at the structure, I have started incorporating wet vent principles to get the vent piping on the interior wall for simplicity.

I have marked up some of the typical fittings. Im not sure about the combo wye + long 90 for bringing the wet vent into the 2nd floor soil line, would this be correct?

Is there a max distance to the LAV on the first floor due to the wet vent? If so, is that only the horizontal run or does it include the vertical leg?

Are the routing and tie in locations acceptable?

NH so per IPC.

Thank you again all, learning a lot this has been hugely helpful.

first floor lav is not vented.

Thanks.

I missed the vertical rise requirement for the wet vent, I guess ill have to find a way to stuff a vent in that wall for the lav.

Feeling comfortable now. Time to get to work.



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