Adding basement bath: how to best extend DWV

Old 04-23-08, 12:13 PM
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Adding basement bath: how to best extend DWV

I'm in the middle of drawing plans to finish off our basement. The home is a basic 1950's rambler. The plan will include a basement bathroom with sink, toilet, and shower. I'm still debating how much of the work to attempt myself, but am educating myself at the very least in an attempt to plan for fixture locations and evaluate any bids and work.

I've laid out a diagram of the existing DWV system. Much is hidden beyond what I can see from the basement and the roof.

The diagram is here: You'll want to use the zoom and scroll to make out details.

There is an existing rough-in for a toilet on the basement floor that needs to be moved to get 15" clearance from the finished wall. I would also like to add the sink and shower as shown by the dotted lines.

What else do I need to know about the viability of the configuration as I've drawn it? I'm trying to determine if tying into the existing vents are sufficient. This would make it much easier than running a new vent. Do you think the dotted lines would make a good addition? Based on what is drawn, does the existing DWV system seem coherent or am I goint to have trouble extending it without fixing something? In addition to the main stack coming out the roof, there are two smaller vents, one is right above the kitchen sink and obviously for the kitchen, the other is not so obvious. Is there a way to find out where the other vent is tied into the system without visibly tracing its path through the attic and walls?

Thanks for reading.
Old 04-25-08, 07:54 PM
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Sounds like you can bust the floor and add a drain line off of the toilet. You should be able to "wet vent" if codes allow. The venting issue will have to be researched...I would avoid the kitchen because of the cabinets. You could bring up the new vent in an existing bathroom, and tie into that one. IMO it looks to be an uneventful, no suprise remodel. But you never know. Talk to some plumbers in your area...good luck.

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