Basement bathroom plumbing rough-in


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Old 01-07-23, 06:28 PM
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Basement bathroom plumbing rough-in

Thinking of tackling the basement bathroom this winter and would like some feedback as to what all I'd need to do with the existing rough-in plumbing. It appears that everything I need for a shower, toilet, and vanity is present. Other than cutting a bit of concrete to extend the shower drain out from the (eventual) wall a few inches, it looks like everything is laid out where I need it. I would only need to run the drain for the vanity over to the left and tie into the 2" drain (also the shower drain) then run a vent from both the vanity and shower into the existing 1.5" vent above the flood level of the sink. Is this an accurate assumption? Below is what is currently in place.





And the proposed modifications shown below (just realized I probably need to tie the vanity drain into the main stack since otherwise the shower would have a wet vent). Blue is the new drainage and orange is new venting.




 

Last edited by mossman; 01-07-23 at 06:50 PM.
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Old 01-07-23, 06:48 PM
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Sounds right to me. Your wall will need to be deep enough to get the vanity drain and shower vent past the main stack, but other than that, looks pretty straightforward.
 
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Old 01-07-23, 06:51 PM
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Good point about the wall thickness. That's fine. No space restrictions on the back side (unfinished storage space). Not sure if you noticed my recent edit...I believe I'd need to tie the vanity into the main stack because otherwise the shower would have a wet vent. Is this an accurate assumption?

Also, just noticed the main stack and toilet rough-in is actually 3" pipe. Not sure if that's an issue.
 
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Old 01-08-23, 05:27 AM
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Presuming it was plumbed correctly originally (no reason to think otherwise), the toilet and shower vent will use the vanity sink vent together. Technically the sink is a wet vent, but it's allowed when it serves the same bathroom group.

So in my opinion, all you need to do is move the shower drain a few inches to where it needs to go. Then add a sanitary tee on the sink drain/vent and extend it over a foot or two into the vanity. Easy peasy!
 
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Old 01-08-23, 05:49 AM
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That would be great if that's the case. The main stack being so close also serves as a vent for the shower and toilet so it seems like what you proposed should be fine. I think the shower drain may actually be in a good spot and I won't have to move it after all.
 
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Old 01-12-23, 06:31 PM
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I'd also like to plumb a drain for a washing machine. The drain farthest to the right is actually 2" coming out of the concrete, so I can easily change the entire length back to 2" to receive the washer drain, then a 1.5" fitting into that from the vanity. Sound good?
 
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Old 01-13-23, 04:53 AM
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Check your venting to make sure it still meets code.
 
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Old 01-14-23, 04:40 PM
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It looks like the tub drain is a few inches off and I'm trying to determine if I can avoid digging up concrete. Is it okay to route the drain and tub overflow as follows? The drain in the floor is 5-1/4" off the wall and the tub drain is 8-1/2" off the wall so I basically need to extend the pipe back about 3" to go up to the tub overflow. Seems like this would be fine. Come to think of it, is it even possible to install a standard tub over concrete without either raising the tub upward (on a platform) or chiseling concrete so the drain can sit below the surface?


 
 

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