Rookie plumber is OK with suggestions on rough in for basement bath addition as to pass inspection.
Any constructive critique is welcome. Just want it done right the first time.
please see isometric that is not exactly to scale. WC will be first in room off to the right.

[i401.photobucket.com]

An extra twist in this one is that the tie in will be to an existing storm drain that collects rain water off the front of the building and ties into the building sewer. Grand fathered in. We shall see what the inspector says.

My main questions are:

1. Clean outs. Can the 2" clean out on the lav and wet vent branch serve as the clean out for the WC in this group.

2. Any suggestions for a good install of the 4" back water valve on building drain? I was thinking that cleanout to the building sewer would be good idea before the back water valve. Who makes the best vault?

thanks again for any helpful input.



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I doubt that they will allow you to connect to the storm drain, because at 3" it is probably running full during a rain storm.

the 3 inch Y that you marked roll up should have a fitting in it so it aims straight for the toilet. then put a 3 x 2 Y in it (also rolled up) to pick up the lav and shower. also roll up the 2 inch Y for the lav.
the 2 inch cleanout can not serve the toilet, it is too small. but the toilet can be removed if snaking is needed. this passes the code requirement.

@ Packy: can you please explain the seeming discrepancy in the chapter 9 code. 905.2 suggest to roll your vent fitting while a sentence under 908.2.1 says to connect horizontally. Can you clear this up for me?

from UPC:

905.2 Where vents connect to a horizontal drainage pipe, each vent pipe shall have its invert taken off above the drainage centerline of such pipe downstream of the trap being served.


908.2.1 Each individual fixture drain or trap arm shall connect horizontally to the wet-vented horizontal branch drain or shall be provided with a dry vent



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the first one applies to vents and they want them ABOVE the flow line of the drain
The second one applies to drains and if THEY were above the flow line, you would essentially be creating "S" traps.

one is talking about vent take off and the other talking about trap arm.
vent take off rolls up (if possible) and trap arm can not roll up towards the trap as it will create a full S trap..

@ HJ:

you were right. Not going to be allowed to tie into existing building storm drain even though this one drops into building main sewer drain. Will have to run bath addition to building sewer drain 25' away as a separate 4x3 comby off the building main 4" CI drain.