Running toilet drain through wall and connecting vanity drain to same pipe

[aa355]

Hello there,

Please see attached sketch for more details, but we want to avoid cutting through the joists below the bathroom and also avoid creating a bulkhead in the family room below. We are located in Toronto, Canada.

We are thinking of using a wall mount toilet with an in wall tank from Geberit. Their catalog shows an elbow connector that appears to allow you to run the toilet drain (I assume this is a 3 1/2" pipe) at an angle instead of straight down through the floor. Can we then run the drain horizontally through the bathroom wall (approx 6 ft) and then down the floor into the mud room? If 6ft is too long what is the maximum length we can run the pipe horizontally (not sure if it needs a slope along the run)?

We would also like to connect the vanity drain in the batbroom to this drain. Is that doable? There is another bathroom directly behind this one and can the drain for the vanity in that bathroom also connect to the same drain above?

Hoping the experts in the forum can provide some insights for us.

Thanks very much!

 

[Cjlambert]

What you suggest is fine. Best of all, the vanity drain can serve as a wet vent for the toilet, provided you run that vanity's drain in 2". You can tie the other bathroom's vanity into the 2" vanity drain in the wall, or you can tie it into the 3" toilet drain further downstream (whichever is more practical).

Maximum distance you can run a toilet drain before connecting a vent is 3m, so you’re fine there. All horizontal drains require a slope of at least ¼" per foot.

 

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[aa355]

Thanks so much for your quick response. Are there any longer term concerns with running a drain through the wall as long as it is sloped as you specified?

 

[Cjlambert]

Nope.

 

[Jadnashua]

As long as you've got proper slope and the traps are properly vented, horizontal (with at least minimum required slope) isn't an issue. Think of the run along the roadway that may be miles from the sewage treatment plant...they try to run that all via gravity (but sometimes, may need pumps, depending on the topography).

 

[Reach4]

You should not make the hole so tight that the pipe generates noise as it expands and contracts with temperature.