Adding a WC on a 3" horizontal run.

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9to12Projects

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First time posting after lurking for a while. So much great information here. Thank you for the great resource Terry.

We were doing a basement bathroom remodel (directly below the 2nd floor master) and seeing all that plumbing made the wheels start to turn. Based on all the code I've read, I think this should be fairly straight forward but if anyone could comment, it would be much appreciated.

There is a 3" main drain stack which currently runs up to the 2nd floor subfloor and then continues up as a 2" vent to the roof, out of a low heel 3x3x2. The low heel 90 3" shoots under the subfloor horizontally (1/4 per foot) to the guest bath toilet with a 3" vent in-line within a few feet of the closet flange. (see mock up picture below). Below the low heel on the main drain stack is a 45* wye which serves the toilet we'd like to relocate.

The plan is just to remove the vertical wye to the toilet on the stack and move the toilet to come off the horizontal run. This would be accomplished with a 3" 45* wye going off to the closet flange. The distance from the flange to the vent on the low heel 3x3x2 is about 3.5'. So in addition to the existing toilet already having a vent "uphill" of the wye, this will also be within 3.5' of 2" vent coming off the vertical stack. New stuff in yellow. Existing in black. No problems, right?

Plumbing.jpg


The only other issue which will just take some creativity is trying to keep that 2" vent = or >45*. There is a 10 inch plumbing wall built into the master as it currently sits, which houses the vent pipe, I'm going to try to get that over to the plumbing wall (2x6) to go back to vertical in there and gain back that square footage. But I'd like to do it without going through the studs of the exterior wall. (I could add shoes but seems best to avoid it if possible.) So I have to ask... it is not possible to change that low heel 3x3x2 to a pair of 90*s back to back just to drop down a bit sooner and then put the low heel 90 onto the drain stack,buying me a bit more rise for the needed run of 2" vent pipe, right?

Thank you Thank you in advance!
Code is UPC.
 

hj

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Last question first. It would be better to use a 45 into a "Y" with a bushing on top.
As for you new "Y", in this case it doesn't make any difference how close it is to EITHER vent, because with the other toilet's flow going past it, that makes it "unvented".
 

9to12Projects

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Thanks hj for the response.

So I guess I need to add a wye to supply a 2" vent (rolled to 90*, right?) on the new toilet line prior to connecting back to the horizontal 3" drain. I think this should be ok. I know there are limits on distance from the trap weir to the vent, do I just use the closet flange to vent for that measurement?

Then I'll put a 45 street to a wye to gain a bit more working room at the end of the run. Thanks
 

Reach4

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Picture seems to show a vent above and below the 45. Is that not enough?
 

9to12Projects

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No because they are to the left and right, NOT above and below. Although codewise it would not make any difference.

Ok, so adding a 45 wye on that branch with a 2" vent should make it good though right? I'm not missing anything am I?

Thanks!
 
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