Under slab back to back baths w kitchens

[Tughillrzr]

View attachment 72734

oops previous layout. Figure second one was easier for plumbing. checking w the more experienced on here how’s this layout look. Making sure I have the least amount of connections and plumbing under slab. Is there a easier way to complete or options with less piping let me know. Besides the shower I’ll also keep both sink and vanity’s drain lines under slab 2” for ease. Both toilets 3” and from second toilet I’ll bump main line from 3” to 4” out to septic. Everything before toilets keep 2”. Once above slab the kitchen and vanity drain lines with vents will be 1.5” . Im thinking a 2” vent line between showers and toilets connections is acceptable to vent toilets and showers. I’ll use a cross tee for bath vanity’s in wall and share the vent line. Just under the cross tee I’ll install in one vanity a clean out tee with plug for snaking if ever need. Only place that’s not visible. Both kitchens I’ll tee in vertical lines for trap connections and continue up for vents. Under slab connections are all wyes , closet bends or long sweeps for toilets and a few long sweep to go vertical on sinks. Shower traps 2” under slab. Bath sizes are 9x6 to get an idea on distances.

 

[Jeff H Young]

kitcompared to floor planchen sinks and lavs are totaly differant on your iso ? not sure about your code but we need clean outs for the 4 inch main not just a 2 inch at the kitchen. basicaly workable with some tweaks

 

[Sponsor]

 

[wwhitney]

Your first drawing is confusing because you're using left-right to mean two different dimensions. I think it would be clearer to use circles for vertical pipes, so the drawing is a projection.

You're in NY ex NYC and so subject to the IPC?

You need to route the kitchen sink drains to come in last, downstream of all the bathroom fixtures. Horizontal wet venting is restricted to bathroom groups. If you move the kitchen sink drains, then a single 1-1/2" vent for the lavatories would vent both WC and both showers as well, under the IPC. But adding the vent between the showers and WCs would be fine, too. For the lavatories you could use a 2x1-1/2x1-/2x1-/2 double fixture fitting; the common drain has to be 2" to be a wet vent carry 2 DFUs.

Cheers, Wayne

 

[Tughillrzr]

Think that will help w the confusion!

 

[wwhitney]

If you changed the drawing(s) in the OP, I don't notice the difference.

Cheers, Wayne

 

[Tughillrzr]

If you changed the drawing(s) in the OP, I don't notice the difference.

Cheers, Wayne

Yah just added new image

 

[Jeff H Young]

yea drawings messed up but just make sure you have your upper terminal cleanout 4 inch and if you have 3 inch after that you'll need c/o there as well

 

[wwhitney]

Yah just added new image

Not seeing anything new.

Best practice is to avoid horizontal double wyes where possible (some jurisdictions may not allow it), better to stagger single wyes. Also, Jeff has a great point about end of line cleanout--maybe the central spine should all be 4" with a cleanout at the end. Then you can have 2" lines (double lav, each shower, kitchen sinks, your extra vent if you keep it) and 3" lines (WCs) running into it.

Cheers, Wayne

 

[Tughillrzr]

yea drawings messed up but just make sure you have your upper terminal cleanout 4 inch and if you have 3 inch after that you'll need c/o there as well

Do I need a clean out above 4” line? Can I just keep the two inch vent for showers and water closets? What If i continue the main line in 4” the entire length and bring up in wall between vanity’s I can do a 4” clean out there and reduce to 1 1/2 for vanity drains and vent. I’ll at least be able to access the c/o with in the vanity. I possibly could have the clean out in mechanical closet but that adds another vent pipe.

 

[wwhitney]

You could do something the drawing below, where circles are risers and the colors mean

yellow = 1.5" (kitchen vents, sink trap arms (lav trap arms could be 1.25"))
green = 2" (double lav vent and drain above cleanout, showers, kitchen sink drains, bonus vent if desired)
blue = 3 " (WCs)
red = 4" (building drain, cleanout in wet wall between lavs)

Actually you could make the building drain 3", not sure if there's an upside to 4". Then the vents on the building drain could be 1.5" like the kitchen sink vents (IPC).

Cheers, Wayne

 

[Tughillrzr]

You could do something the drawing below, where circles are risers and the colors mean

yellow = 1.5" (kitchen vents, sink trap arms (lav trap arms could be 1.25"))
green = 2" (double lav vent and drain above cleanout, showers, kitchen sink drains, bonus vent if desired)
blue = 3 " (WCs)
red = 4" (building drain, cleanout in wet wall between lavs)

Actually you could make the building drain 3", not sure if there's an upside to 4". Then the vents on the building drain could be 1.5" like the kitchen sink vents (IPC).

Cheers, Wayne

View attachment 72755

hey thanks for all the help!!
Yes I’ll just plan on routing kitchen waste lines at end of main line after the bath groups. I never use 1.25 on vanity’s, I just don’t see the point of using them. I’ll Definitely use 3” main. I guess I can just bump it up to 4” outside for septic . So I can remove the bonus vent and showers and wc will wet vent off of the 1 1/2 in vanity vent since main line is now all 3”. Thanks again!

 

[wwhitney]

Just an FYI, the IPC allows a single 1-1/2" vent to vent two bathroom groups. The UPC would require that the bathroom groups be kept separate and would require separate 2" vents for each one.

I have no experience with the IPC, so a single 1-1/2" vent for both bathroom groups seems odd to me. You might want to use a 2" vent on the double lav and/or rough-in through the slab for the bonus 2" vent. Maybe someone who's worked under both codes can comment.

Cheers, Wayne

 

[Reach4]

Is this a multi-unit building?

 

[Tughillrzr]

Is this a multi-unit building?

Technically it’s a two family with Shared utilities.

 

[Tughillrzr]

Just an FYI, the IPC allows a single 1-1/2" vent to vent two bathroom groups. The UPC would require that the bathroom groups be kept separate and would require separate 2" vents for each one.

I have no experience with the IPC, so a single 1-1/2" vent for both bathroom groups seems odd to me. You might want to use a 2" vent on the double lav and/or rough-in through the slab for the bonus 2" vent. Maybe someone who's worked under both codes can comment.

Cheers, Wayne

Yes maybe someone will chime in. I’ll will have to search more on my part as well. 1 1/2 vent bath group seems odd. I know 2” is acceptable for one total bath group. I’m wondering what changes with multi unit. I may have to vent each shower separately. I’m thinking that bonus vent will be required for wc. Thought when venting, I read that I can only share two fixtures from each group on single vent.

 

[Jeff H Young]

3 inch cleanout meets code at lavs not much fun bringing machine in . sometimes we keep running the waste line to outside its just a straight run with a 90 on end a bit more work but if you ever need it you'll be happy its there 2 units rental? you don't want to drag a machine in the house . just a thought though certainly not mandatory run 2 inch to those kitchen sinks with clean outs just because .

 

[Tughillrzr]

3 inch cleanout meets code at lavs not much fun bringing machine in . sometimes we keep running the waste line to outside its just a straight run with a 90 on end a bit more work but if you ever need it you'll be happy its there 2 units rental? you don't want to drag a machine in the house . just a thought though certainly not mandatory run 2 inch to those kitchen sinks with clean outs just because .

Yes I figured all 3” main now, planned on using 2” for kitchens with clean outs for each. What do you think w regards to the showers and wc venting? One two inch acceptable ? And revent each shower? Yes I’m building a 2 unit vacation rental. Machine dragging definitely not fun. Been there. So sometimes you would continue the main line out side and add a 90 w clean out plug? So you can snake from front to back in direction of septic/sewer? Interesting! Not a bad idea.

 

[Tughillrzr]

Well project is in motion. Next is radiant tubing set up.

 

[Jeff H Young]

Yes I figured all 3” main now, planned on using 2” for kitchens with clean outs for each. What do you think w regards to the showers and wc venting? One two inch acceptable ? And revent each shower? Yes I’m building a 2 unit vacation rental. Machine dragging definitely not fun. Been there. So sometimes you would continue the main line out side and add a 90 w clean out plug? So you can snake from front to back in direction of septic/sewer? Interesting! Not a bad idea.

beside running outside with clean out, some people will put a sweep on at outside wall and a cleanout tee pointed to outside and cap the top off. because a cleanout tee fits in a wall nicely. just a thought looks like you've got it built though and really looking good! good luck with project look forward to more

 

[Tughillrzr]

beside running outside with clean out, some people will put a sweep on at outside wall and a cleanout tee pointed to outside and cap the top off. because a cleanout tee fits in a wall nicely. just a thought looks like you've got it built though and really looking good! good luck with project look forward to more

Thanks ! I’ll have a 3” clean out in mechanical closet. It’s a straight shot from entry door if it ever needs to be snaked. So not bad accessibility.