Toilet/WC above Shower?

[Martin F]

I'm trying to get a wall hung toilet installed in my condo but failed permit review because as I understand it, the wet vented drain for the WC has to be at the same elevation or lower than other wet vented plumbing group fixtures such as the shower.

Review Comment: "Bathroom, relocated toilet, not as per FBC 912.1.1, (other fixture drains shall connect at same of above WC elevation, see SH)"
Code Reference: https://codes.iccsafe.org/content/FLPC2023P1/chapter-9-vents#FLPC2023P1_Ch09_Sec912

I'm on the top floor of the building and have 26 showers below my WC so I am thinking it must be possible using the right venting for the shower which might be different for the showers below me since they are allowed to be under a WC.

Could adding a (dry?) vent for the shower (see red dashed line in drawing) that connects above the lavatory/sink which is the last fixture connected before what would considered the dry vent(?) (where the existing vent stack from units below also connects) fix the issue? This way the shower vents above the WC? or is there another (better/right) way of doing it?


(shower drain is 1-1/2" and not 2" as indicated).


Hope someone out there can help.

 

[MicEd69]

Yes, that would be acceptable. The pipe you label as an existing soil stack is really a vent stack once no wastewater enters it. As such, the soil stack ends at the point the 2" lavatory drain enters it. I assume the lavatory is close enough to the soil stack so that it is vented by the vent stack, or there is a separate vent line that is connected to the vent stack you show in dashed lines. So, what you are doing is simply connecting a dry vent into an existing vent stack.

 

[Martin F]

Yes, that would be acceptable. The pipe you label as an existing soil stack is really a vent stack once no wastewater enters it. As such, the soil stack ends at the point the 2" lavatory drain enters it. I assume the lavatory is close enough to the soil stack so that it is vented by the vent stack, or there is a separate vent line that is connected to the vent stack you show in dashed lines. So, what you are doing is simply connecting a dry vent into an existing vent stack.

Thanks a lot for your reply - I really appreciate it.
This is the only review comment that needs to be fixed before I can get my permit and get started.

The Lavatory is wet vented and 2" because the run is slightly more than 6 ft. which would be the max. for 1-1/2".
I'm not connected to the 4" vent stack on the right - it only serves the units below me.

All fixtures (shower, water closet, lavatory) are connected to the 4" stack labelled S.S. (Soil Stack).
Only change I am trying to make is to move the WC drain from being connected at the same elevation as the Shower to above slab so it can be a wall-hung toilet and moved to the side to make more space for the Shower, which resulted in the failed plan review due to code saying the wet vented WC can't be above the wet vented Shower (as I understand it).

Is it also considered a Dry Vent from the Lavatory and above regardless of whether the drain carries rain water from the roof?

In that case I will change the drawing so it shows a vent (dashed line) above the Lavatory connection and connect the dry vent from the shower as indicated in the drawing.

 

[MicEd69]

First, are you saying that the roof is draining through the stack? I'm assuming you only mean that there is a small amount of rainwater that falls into the open pipe. That is normal and is not considered a plumbing waste flow.

Second, if the sink drain is 2" and you are under IPC or similar code, and not UPC, then the lavatory is dry vented assuming the above is true. Your shower will also be dry vented then.

 

[Martin F]

First, are you saying that the roof is draining through the stack? I'm assuming you only mean that there is a small amount of rainwater that falls into the open pipe. That is normal and is not considered a plumbing waste flow.

Second, if the sink drain is 2" and you are under IPC or similar code, and not UPC, then the lavatory is dry vented assuming the above is true. Your shower will also be dry vented then.

Thanks once again for taking your time to reply.

It looks like Florida have adopted IPC (according to google).
The new drain for the Lavatory will be 2", but the existing drain for the Shower is 1-1/2" (the 2" indicated on the drawing is a mistake).

I don't know how the stack is connected at the roof, I just know that it is where it terminates. The way you are asking, it doesn't sound right to be draining rainwater from the roof through the stack, so maybe it is not and the building have separate drains for the roof.

 

[MicEd69]

Yes, roof drains are not supposed to be connected to sanitary sewers. That would tend to hydraulically overload the waste treatment system.

Shower drains per today's code should be 2". But as this is existing, you should be "grandfathered" in as you are only adding a dry vent for it.

 

[Martin F]

Perfect - Thank you.

Would it be a good idea / make a difference that I indicate on the isometric drawing that everything above the lavatory connection is a dry vent and only below it is considered soil stack?

Or should adding the 1-1/2" vent to the shower drain be enough to fulfill code requirements?

I'm a little nervous about fixing the mistake of the shower being 1-1/2" and not 2" as indicated, so I might just let it be on the drawing to not create problems for myself :-/

Have a great weekend.

 

[MicEd69]

I wouldn't even mention the shower drain size. Just show the new 1 1/2" vent to the vent stack.
Here's a pretty good sketch of the various components of a DWV (Drain - Waste - Vent) system.

 

[Martin F]

I wouldn't even mention the shower drain size. Just show the new 1 1/2" vent to the vent stack.
Here's a pretty good sketch of the various components of a DWV (Drain - Waste - Vent) system.

I have made a new isometric drawing to submit for permit review - is it correctly understood?

The 1-1/2 Dry vent (previously marked with red) is connected above the lavatory and the vertical vet went to hopefully fix the problem highlighted in the review.

The 4" stack that was previously marked as S.S (Soil stack) has been split into the upper part being a Vent stack and the part below the highest fixture / lavatory is the Soil Stack.

 

[MicEd69]

I have made a new isometric drawing to submit for permit review - is it correctly understood?

The 1-1/2 Dry vent (previously marked with red) is connected above the lavatory and the vertical vet went to hopefully fix the problem highlighted in the review.

The 4" stack that was previously marked as S.S (Soil stack) has been split into the upper part being a Vent stack and the part below the highest fixture / lavatory is the Soil Stack.


View attachment 45469

Looks good.

You don't identify the fitting at the connections, which are important. If I understand correctly, the only new connections you are making is the toilet to the soil stack, the shower vent to shower drain, and the shower vent to the stack. The toilet connection to the stack needs to be a sanitary tee. The shower vent connection to the stack can be a sanitary tee or a wye or a combo wye and 1/8 bend. The shower vent connection to the shower drain is dependent of the interpretation of the IPC code the inspector and/or the AHJ (Authority Having Jurisdiction). Many interpret the code to say a sanitary tee on its back can be used as a vertical vent connection to a horizontal drain. But many also interpret the code as saying that connection must be a combo wye and 1/8 bend.

If you don't need to identify the fittings, then you are good to go now. But you need to be sure to determine what fittings the inspector will approve upon inspection visits to avoid "do-overs". I will say that if the inspector/AHJ does interpret that a sanitary tee on its back is OK for a vertical vent to horizontal drain is acceptable, they will also allow a combo fitting for that connection. Not the case if it is the other way around.

 

[Martin F]

Yes correct, toilet drain is moved from below slab and same elevation as the shower to above slab (which caused the failed review), and the vent is now added to the shower so it is connected above the toilet and hopefully is able to pass permit review.

Makes sense about the fittings and I will make sure to clarify that before the work is being done. Hopefully the reviewer is not going to come back asking for what fittings will be used. The reviewer did not mention it in the initial failed review (in relation to the toilet), but it might come up for the vent. :-/

The whole stack above slab will be replaced with PVC but not under this permit, but it is agreed with the association now that the wall is open and as they are doing the same in other units.

If a sanitary tee is used for connecting the shower vent in the 4" stack it should be installed upside down as I understand it?

Should the Wye point towards the shower drain or the stack?

Thank you so much for you help, also for brining up additional things to look out for such as the fittings - I really appreciate it and its a great help for me.

 

[Twowaxhack]

Use a combination wye/45 and point it toward the stack in the shower drain.

 

[Martin F]

Use a combination wye/45 and point it toward the stack in the shower drain.

Thanks.

I have also reached out to the building department as suggested by MicEd69, to confirm whether it needs to be a combo wye with 45 degree bend or if they allow a sanitary tee, just to be on the safe side.

I have resubmitted the revised permit drawing and is now waiting for another review.

 

[Twowaxhack]

Thanks.

I have also reached out to the building department as suggested by MicEd69, to confirm whether it needs to be a combo wye with 45 degree bend or if they allow a sanitary tee, just to be on the safe side.

I have resubmitted the revised permit drawing and is now waiting for another review.

Just use a combination fitting, they’re legal everywhere and it’s better plumbing….

 

[Martin F]

Thanks to both of you - I just passed the Plumbing Review and I also got to talk to the reviewer who confirmed what you were both saying that a combo wye shall be used.

 

[MicEd69]

Congrats and you are welcome. Good luck on the construction phase.