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Discussion Starter #1
Greetings,

I spent significant time modeling/commenting this, so hopefully you'll be willing to take a minute or two to give advice! I'm completely re-doing the plumbing in my basement, and want to start breaking concrete asap, but need some guidance (I did talk to the city inspector, and he will come look before I glue it up, but I need to have the layout planned before digging obviously). Existing basement bathroom/sink/floor drains have no venting whatsoever (all wet vented, would never pass these days). It's all coming out and new bathroom getting roughed in while changing layout as well.


Option #1: What I'd like to do: 4" soil stack transition from vertical to horizontal under the floor via 4x4x4 wye +45 on its back. The heel of the wye will accept the 4" drain coming from the upstream fixtures (which will all be separately vented). This option is much preferred due to geometry and other things you can't see (such as the water heater in the way- I already have to move the furnace to do this and it's cold here in MN!).


Option #2: long sweep 90 to bring soil stack to horizontal, then wye +45 (horizontal) into a new 4" line which connects to the existing cast iron to the street. The heel of the wye will again connect to the upstream stuff. The only problem is that this will cause me to use a bunch of extra fittings and have extra bends. I'd like to keep the flow as smooth as possible. The picture doesn't do justice to the added bends I'd likely have to get the geometry to work out- it's pretty tight space-wise around there but I couldn't manage to model all the jogs, etc.

I haven't shown the floor drain and all the other obstacles in the way... there's a lot going on in this small area.

So... would it be better to have the vertical stack turn 45, hit the wye, and continue on down, or to have a long turn 90 and hit the wye while horizontal? Does it matter? If I go with option 2, I am aware that I have to go 10 pipe diameters downstream of the base of the stack to tie other things into this pipe.


Please tell me (but only if it's correct) that I can do option 1!


Thanks for your time.
 

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Either way is OK with my code. I didn't take the time to read your link tho.
2 changes that maybe requested: Add a clean out at the base of the 4" stack and change the 3x2 santee(toilet vent) to a wye/45.
 

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Discussion Starter #5
...Add a clean out at the base of the 4" stack and change the 3x2 santee(toilet vent) to a wye/45.
Thanks,

Yep- planned on the cleanout but couldn't model it.

As far as the wye/45 on the vent- I assume this is just added insurance against getting any waste in the vent line? And I also assume it has to be oriented "correctly" even if it's only a vent (i.e., facing downstream as though it were a waste line?)
 

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Thanks,

Yep- planned on the cleanout but couldn't model it.

As far as the wye/45 on the vent- I assume this is just added insurance against getting any waste in the vent line? And I also assume it has to be oriented "correctly" even if it's only a vent (i.e., facing downstream as though it were a waste line?)
Thats correct. Any vent pipes below the flood rim of the fixtures(rule of thumb is 42" above the floor) needs to have approved drainage fittings- you cannot have a santee on its back when used for drainage- must be a wye
 

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Discussion Starter #8
Toilets are self venting, ask the inspector if you can eliminate the w/c vent.
Thanks for the reply. I did ask him about this, and was told that since it's on a different level (basement) than the mail soil stack coming from the upstairs bath, that it would need to be vented separately. The only thing he'd allow is a 1 DFU (lav?) item to wet vent via the stack.

Makes it a bit more tricky to fit all this in and still have a dedicated vent that can still be concealed in a wall. It's like a giant puzzle- I have respect for you guys that figure these things out all day every day...
 
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