Basement bathroom DWV configuration questions

[David C]

I am preparing to build a basement full bathroom with stand up shower.
I am looking for help with configuring the DWV system that will go under the floor.
I have drawn a blueprint to simulate the build. I tried my best to scale it correctly but since its a rectangular shape its a little funny.

Notes: the soil stack listed has a 3" vent thru roof for venting. It will be 1/4 sloped i assume. I think I can tap into the existing vent pipe to vent the new DWV system if needed.

I will keep checking if anyone would like more info before giving advice.
So here we go

 

[James Henry]

Pretty easy wet vent system. start with the lav drain, the shower ties in 2nd and the toilet ties in last. you can reconfigure the drain lines to make the angles work with the fittings, you just need to follow the order in which you tie the fixtures into the drain line.

 

[Sponsor]

 

[David C]

Thank you so much! I was thinking of having to branch off the existing main line at some odd 70 degree angle and running straight to shower instead of following the drain line angle and making the shower branch connect after the Lav...

I have one last question. If I can't bring the vent into the existing roof vent can I use one of those AAV vents I think they are called?
The one way vents i believe are rated up to 8 DFUs on 2". The soil stack has a pretty high connection from upstairs plumbing and im not sure if i can fit a Wye between it and the floor above..
I'll attach a picture

I simply couldn't picture it but thats exactly what I was looking for!!!

 

[James Henry]

Good luck.

 

[David C]

Thank you so much! I was thinking of having to branch off the existing main line at some odd 70 degree angle and running straight to shower instead of following the drain line angle and making the shower branch connect after the Lav...

I have one last question. If I can't bring the vent into the existing roof vent can I use one of those AAV vents I think they are called?
The one way vents i believe are rated up to 8 DFUs on 2". The soil stack has a pretty high connection from upstairs plumbing and im not sure if i can fit a Wye between it and the floor above..
I'll attach a picture

I simply couldn't picture it but thats exactly what I was looking for!!!

 

[James Henry]

https://up.codes/viewer/michigan/mi-plumbing-code-2015/chapter/9/vents#9




read this.

 

[wwhitney]

In that last photo, are you 100% sure there are no drains attached to the cast iron above the subfloor?

Cheers, Wayne

 

[David C]

In that last photo, are you 100% sure there are no drains attached to the cast iron above the subfloor?

Cheers, Wayne

Not 100%, the sink above the subfloor might connect above the subfloor. Its likely it travels horizontal inside the wall and into what i thought was just the vent pipe. It just dawned on me I don't see a sink drain. But that bathroom is next and I could have it come down through the subfloor when I remodel that one

 

[James Henry]

To your original thought, this is OK too.

 

[David C]

https://up.codes/viewer/michigan/mi-plumbing-code-2015/chapter/9/vents#9




read this.

So thats a no because its not at least 5 branch intervals between the proposed AAC and the top of the stack? Section 918.3.1
I feel terrible for you plumbers, thats some seriously dry reading lmao!

 

[James Henry]

So thats a no because its not at least 5 branch intervals between the proposed AAC and the top of the stack? Section 918.3.1
I feel terrible for you plumbers, thats some seriously dry reading lmao!

Yea, you have to like technical literature and reading, which I always have. I would contact you local building department and ask if you can use an AAV just to be sure, it will save you a lot of work. They may let you, they have the last word.

 

[James Henry]

So thats a no because its not at least 5 branch intervals between the proposed AAC and the top of the stack? Section 918.3.1
I feel terrible for you plumbers, thats some seriously dry reading lmao!

I don't quite understand what your saying. go the the "DEFINITIONS " section of the code and look up " BRANCH INTERVALS" I don't think it means what you think it means.

 

[David C]

I don't quite understand what your saying. go the the "DEFINITIONS " section of the code and look up " BRANCH INTERVALS" I don't think it means what you think it means.

BRANCH INTERVAL. A vertical measurement of distance, 8 feet (2438 mm) or more in developed length, between the connections of horizontal branches to a drainage stack. Measurements are taken down the stack from the highest horizontal branch connection

918.3.1 Horizontal Branches

Individual and branch-type air admittance valves shall vent only fixtures that are on the same floor level and connect to a horizontal branch drain. Where the horizontal branch is located more than four branch intervals from the top of the stack, the horizontal branch shall be provided with a relief vent that shall connect to a vent stack or stack vent, or extend outdoors to the open air. The relief vent shall connect to the horizontal branch drain between the stack and the most downstream fixture drain connected to the horizontal branch drain. The relief vent shall be sized in accordance with Section 906.2 and installed in accordance with Section 905. The relief vent shall be permitted to serve as the vent for other fixtures.

[FONT=Open Sans, sans-serif]That sounds like the horizontal branch in basement being only 8 ft below the highest horizontal branch/branches or at most 16 ft below the top of the stack vent would not meet the 5 branch intervals from the top of the stack. [/FONT]

 

[James Henry]

BRANCH INTERVAL. A vertical measurement of distance, 8 feet (2438 mm) or more in developed length, between the connections of horizontal branches to a drainage stack. Measurements are taken down the stack from the highest horizontal branch connection

918.3.1 Horizontal Branches

Individual and branch-type air admittance valves shall vent only fixtures that are on the same floor level and connect to a horizontal branch drain. Where the horizontal branch is located more than four branch intervals from the top of the stack, the horizontal branch shall be provided with a relief vent that shall connect to a vent stack or stack vent, or extend outdoors to the open air. The relief vent shall connect to the horizontal branch drain between the stack and the most downstream fixture drain connected to the horizontal branch drain. The relief vent shall be sized in accordance with Section 906.2 and installed in accordance with Section 905. The relief vent shall be permitted to serve as the vent for other fixtures.

[FONT=Open Sans, sans-serif]That sounds like the horizontal branch in basement being only 8 ft below the highest horizontal branch/branches or at most 16 ft below the top of the stack vent would not meet the 5 branch intervals from the top of the stack. [/FONT]

No. Ignore that section.

 

[David C]

Hows does this look? I couldn't find a 3x2x2 wye for lav and shower so I used a 3x3x2 then reduced the lav down to 2 inches before the bend.
No Sani-tees horizontal, cleanout uses one because that made sense. Lol
Also I have the closet bends with either a street end or hub, does that matter?
The street end had a smoother transition from 4to3 but that will likely mean 2 couplers in it instead of the hub end having only 1.

 

[James Henry]

Hows does this look? I couldn't find a 3x2x2 wye for lav and shower so I used a 3x3x2 then reduced the lav down to 2 inches before the bend.

Fine.

No Sani-tees horizontal, cleanout uses one because that made sense. Lol

Must be a combo or wye/18th bend.

Also I have the closet bends with either a street end or hub, does that matter?

Your choice.

The street end had a smoother transition from 4to3 but that will likely mean 2 couplers in it instead of the hub end having only 1.

less fittings the better.

Did you figure out the lav vent?

 

[David C]

Must be a combo or wye/18th bend.

For the cleanout? Or just any horizontal connections?

The Lav vent is gonna run with the AAV, if I have issues when selling the house one day ill have to connect it to existing roof vent. After I remove a connection that exists in the above floor as a drain currently.

 

[James Henry]

https://codes.iccsafe.org/content/IPC2018/chapter-7-sanitary-drainage

IPC Table 706.3.

 

[Reach4]

David: How much cast iron coming down do you intend to keep? How will you support that?

Also, you could alternatively run the toilet as illustrated in this markup, replacing two combos with two wyes. Not a big deal, but it does cut down on 90 degrees of turns. Downside is that getting the toilet at the desired rough-in place, and you already have the combos. And you would have to take out that extra concrete piece.

 

[David C]

https://codes.iccsafe.org/content/IPC2018/chapter-7-sanitary-drainage

IPC Table 706.3.

So is that supposed to be a wye with a 1/8?
I just mimicked the cast iron they already have.
Is that in a wrong place? Never had to deal with cleanouts before sadly.