View Full Version : Draining/Venting Tips Needed

08-21-2012, 06:24 AM
Hello everybody,

Your input and feedback on this is very welcome.

I am combining what used to be side by side bathroom and laundry rooms in my basement into one larger room and of course this necessitates moving plumbing.

The previous plumbing all seemed to be draining just fine.

Please see the attached photos for a reference:


My main areas of concern are as follows:

The existing dry vent that I am tying into is 2". I presume given teh fact that there were no past problems that this is sufficient for this bath/laundry group
Given that the shower is now downstream from the toilet will this be an issue with venting? They will both use the sink's wet vent
Do all of my tie ins to the main horizontal line (shower, toilet, sink) need to be Y-shaped?
As you can see the two vents will tie in at the ceiling below the joists. Is the way I have it drawn out OK? Ideally I would run the line straight to both areas but you can see some stuff gets in the way so I have to make that awkward shape. This vent ties into the stack that vents the kitchen. The kitchen sink does not drain through this stack.

Please let me know if anything is unclear about my drawings.

Am I on the right path here?

08-21-2012, 07:22 AM
Your terminology may be confusing. The kitchen sink line should vent the new toilet, but BOTH the lavatory and shower need their own vent lines. In order to make the new installation, you will have to take out and redo almost all of the piping.

08-21-2012, 02:21 PM
Thanks for your reply HJ. I certainly don't mind redoing everything, I just want to be sure I'm doing it right! That's where your help is extremely appreciated.

That being said, there are a couple of issues I have learned of:

The vent that the old washer and bath groups were using is a 1.5" vent
The washer is supposed to drain AFTER the bath group so as to prevent sudsy waste soap from blocking vents for the bath group

So if I vent the toilet to the kitchen sink/dishwasher drain, can I simply vent the new lav, shower, and laundry to the existing 1.5" vent?

Thanks for your feedback

Tom Sawyer
08-21-2012, 02:39 PM
The kitchen sink drain/vent can not be used to wet vent a toilet. Only bath group fixtures can be wet vented.

08-21-2012, 03:11 PM
Hi Tom,

So are you more in favor of my initial plan?

08-22-2012, 11:51 AM
Here are a couple more shots to illustrate what I have and what I am hoping to do:

My main line is 4". I double checked.

So I Photoshopped up some shots to further clarify things, and also illustrate tying into the 4" main AFTER the bath group.


Is there a minimum distance to maintain between tying the laundry into the main drain and the wye for the shower?

08-22-2012, 04:13 PM
qquote; Is there a minimum distance to maintain between tying the laundry into the main drain and the wye for the shower

I wouldn't even waste my time doing it that way. But I still do not see any sign of a vent for the shower.

08-22-2012, 06:40 PM
The shower is vented through the 2" lav wet vent. Correct? Incorrect?

How would you propose to drain the washer?

I do sincerely appreciate your feedback. That being said, could you throw in suggestions when I said I did something wrong? Your help is invaluable!

Tom Sawyer
08-22-2012, 06:47 PM
depends on how far away the lav is. Most codes it can't be any more than 6' some are 5'

08-22-2012, 06:51 PM
Have a look


Tom Sawyer
08-22-2012, 07:02 PM
It appears to be within the right distance. there appears to be enough room to cut in both wye's just move the shower wye up and the laundry wye below it.

08-22-2012, 09:19 PM
So you think it's OK like this? Simply run the wye for the laundry as far down as possible?