How to fix missing drain pipe sub slab plumbing

[Idahoan208]

Ok I feel really dumb asking this...I'm in the process of building a house and I just noticed (slab was poured in October already and I'm just getting to the basement after remodeling the top levels) that the basement bathroom only has a bath drain and a toilet drain, nothing for the sink. I was kind of in disbelief and dug up old photos to make sure I didn't screw something up as we poured but sure enough there's no sink drain. Am I totally screwed here? Do we need to cut up concrete and splice in the sink drain now to have a sink? I just handed the contractor plans and the sink is clearly on there. His fault? My fault for not catching it (there's no GC on the job, just me)? I'm so bummed. Thanks for your help.

 

[Terry]

Which contractor did you show the plans to? If you hired a plumber to do the rough plumbing, there should have been plumbing for the sink drain. Who did the plumbing? Are you really sure that nothing roughed for a sink? At the worst, yes you will need to pull from somewhere. Either from the ground or from a waste stack meant for a higher floor.

 

[Sponsor]

 

[Idahoan208]

I gave the floorplan to a plumbing contractor which clearly has bath, sink, and toilet on it, plus he did kitchen drain and washer dryer. In the bathroom coming up out of the concrete I have one pipe for the tub, one for the tub vent, one for the sewer, and one for toilet and one for the toilet vent. Attached a photo pre-slab. There's supposed to be a sink between the tub all the way left, and toilet.

 

[Terry]

The trap arm for the sink comes off the toilet vent. No need to go into concrete.

The vent for the tub and the sink/toilet can tie together at 42" above the floor, and then continue up through the roof.

 

[Idahoan208]

Awesome thank you! Do the vents need to go straight up or can they turn and then go up as long as they vent through the roof?

 

[Terry]

Plumbing vents and waste are done like this in most cases.

The vents above the flood level can make some bends.

 

[wwhitney]

I may be mistaken, but I think the riser you called a toilet vent is intended for a cleanout. And as Terry mentioned, the pipe you called the tub vent is intended as the lav drain. The lav gets dry vented, and it wet vents the tub and WC.

As for dry vents, they can go horizontal (pitched at 2% back to a drain) at an elevation of at least 6" above any fixture served by the vent.

Cheers, Wayne

 

[Terry]

I may be mistaken, but I think the riser you called a toilet vent is intended for a cleanout. And as Terry mentioned, the pipe you called the tub vent is intended as the lav drain. The lav gets dry vented, and it wet vents the tub and WC.

As for dry vents, they can go horizontal (pitched at 2% back to a drain) at an elevation of at least 6" above any fixture served by the vent.

Cheers, Wayne

The trap arm for the lav could come from either the tub vent or the toilet cleanout, which extended becomes a vent for the toilet and can also be for the lav. You have options there.
For the tub to be part of the wet vent, the line should be 2".

 

[Jeff H Young]

Technicaly if lav dosent come off of tub vent inspector could call you on a horizontal vent not being a minimum above flood level. In upc code its often ok with inspector they either dont know , dont care or dont want to make you change it to comply. kind of a minor thing around here. Inspector wouldnt know that vent is flat all this time after concrete. just bringing it up in case anyone is interested. BTW Am I the only one that needs cleanouts? seems like every job is missing cleanouts on this site that tubs gotta be 5 foot off the main maybe this is ipc code?

 

[wwhitney]

The trap arm for the lav could come from either the tub vent or the toilet cleanout.

Good point. I see Idaho uses the UPC, I was thinking IPC, which is subtly different. So two questions to the OP:

1) Is the left hand riser 1-1/2" or 2"? If it's 1-1/2", it can only serve as a dry vent for the tub, and your lav trap arm will need to connect to the 3" riser.

2) The UPC requires that the total area of vents through the roof be at least as large as the minimum allowed building drain size. So how many WCs in the house? If 3 or fewer, then the minimum building drain allowed is 3"; if 4 or more, it's 4".

Do you have a plan for meeting that requirement? Because one option is to use the 3" riser as a vent for the WC and run it through the roof as 3"; but if you have other vents, it would simpler to reduce it to 2" (if it is serving as a vent) or not run it up higher (if it is a cleanout only).

Cheers, Wayne

 

[Jeff H Young]

good call Wayne, using the 3 inch as a clean out only allows the 2 inch flat vent to become a wet vent therefore his vent isn't illegal just needs 2 cleanouts one for the w/c and one for end of line to tub and lav .