Does this drain mockup photo look ok for an upstairs bath?

[Seattle]

When I bought this house it had an unfinished upstairs bathroom which I am now going to finish. The 3" drain line runs down the first floor wall into the basement and then connects to the 4" main. I can't change that vertical drop to the basement as it's behind the finished walls of the first floor.

I put together this mockup to show what my plan is on hooking up a toilet, shower and sink in this upstairs bathroom. This will all be below the upstairs floor, inside a 2x8 floor joist so I don't have much space. Everything does fit though and has the 1/4" slope per foot.

Is this sanitary tee the right one to use? Does everything else look ok? The only thing I thought I might change is to add a cleanout at the bottom of the vent (which is in an accessible kneewall).

Thanks very much!

 

[hj]

drains

That is NOT a "sanitary tee", it is a "two way cleanout" and would NEVER be used for your purpose, or anything else except as an outdoor main line cleanout. In fact, it is a poor fitting even for a cleanout, unless it is only about 18" below the ground level. All a cleanout at the bottom of the vent would give you would be a way to snake the line over to the toilet, because it would NEVER turn downwards into the riser.

 

[Sponsor]

 

[Seattle]

What about this 3" double sanitary tee in that spot where it connects to the 3" riser going to the basement? I could use the top port for a cleanout and have it inside a cabinet.

 

[Terry]

If the 3" line is used as a vent for the downstairs bath, then no waste can be put down it.
You must determine if that is "really" a future waste line, or if you are attempting to dump a bathroom down your vent.

If it really is a future waste line provided for a bathroom, then the wall will need to be opened up to plumb it properly.
It is extremely difficult to run what you want in a 2x8 flooring system.

For the toilet, Do not use an illegal sanitary cross.
The toilet will skip right over and force water out of your shower trap. Maybe even fill your shower arm with waste. A sure way to make a nasty mess.

Even a double fixture fitting with more sweep will cause you problems there with the new toilets. They also skip across the fitting with the new toilets.
I would bring the shower in to a wye below a santee for the toilet.

Bring in the shower below the toilet. The shower needs to be vented separately from the toilet, but the two vents can tie together at 42"

Helpful Plumbing Hints for Residential Construction by Bert Polk Plumbing Inspector Lincoln County

The toilet can vent below the flange in the wall below if needed.

 

[Seattle]

Terry, Thanks very much for explaining how my current idea is not going to work. I was about to start gluing things together yesterday but read your reply in-time. The downstairs bath DOES use that 3" line going upstairs for a vent----very clever of you to think this might be the case.

There is an old, unused vent line for the downstairs bath that a previous owner bypassed years ago. That vent line goes from the basement all the way to the roof and isn't being used so I can easily hook it up again to the downstairs bathroom.

After I reconnect that old unused vent line back to the downstairs bathroom, that will make this 3" line going upstairs as an exclusive drain for the upstairs bathroom.

I guess I'll have to open the downstairs wall to get the upstairs shower and sink to connect BELOW the upstairs toilet.

Thanks for the link to Bert Polk's pdf document which is a good summary of basic drainage.

I'll study what I need to do and come back if I have further questions.

Thanks again.