Toilet waste pipe above joists

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PtraP

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Looking to relocate a 2nd story master bedroom toilet out of a long narrow room (5'Wx10'D) adjacent to an existing walk-in closet to increase closet space. Floor joists run perpendicular to the proposed waste line relocation so holes/notches are not an option over that 10'D distance. Can I install a rear discharge toilet and run the waste line, with proper slope, back to the original location at the rear of the room above the subfloor and box in/drywall the exposed PVC pipe along the stud wall?

Thank you in advance, this site has been invaluable over the years.
 

Caliber_Plumbing

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Where are you living? before making any plumbing or structural changes, follow your local codes and regulations.
Since you mentioned that the floor joists run perpendicular to the proposed waste line relocation, you're right to be concerned about making holes or notches in them. Structural integrity is crucial, and altering load-bearing members of the structure can compromise the safety of your home. If you are planning to install a rear discharge toilet, make sure to choose a toilet model that is suitable for your installation plans.
 

John Gayewski

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Yes a rear outlet toilet will work. But for the most part residentially, the current rear outlet toilets that are used, come with the carrier and tank as one unit in the wall. They are actually very very nice. But your gonna likely stuck with that general design. Meaning you need open wall space with nothing inside of the wall.
 

PtraP

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Thank you John. I'm thinking of using a standard floor mount toilet with rear discharge not the in-wall tank floating seat design. In- wall is an option and definitely cool but may be cost prohibitive.
urbipqplspm2e2wpfb0ce6u9hr6rb33x.jpg
 

Tuttles Revenge

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Yes, I've used a standard rear discharge floor mounted toilet to do exactly what you're describing.. But 10ft requires 2.5" of fall at 1/4" per foot.. And since your pipe is centered at 4" above floor but the bottom is 1.5" down from that.. its not much distance

Look at duravit toilets, their discharge is at almost 8" above finished floor so you can travel almost 2x as far. They have a different style of connection similar to a Unifit.

One that we did to create a bathroom in an attic
1692039399468.png


Schematics from Duravit.. they look odd because I combined a couple of theirs.
1692039865611.png
 
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PtraP

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Yes, I've used a standard rear discharge floor mounted toilet to do exactly what you're describing.. But 10ft requires 2.5" of fall at 1/4" per foot.. And since your pipe is centered at 4" above floor but the bottom is 1.5" down from that.. its not much distance

Look at duravit toilets, their discharge is at almost 8" above finished floor so you can travel almost 2x as far. They have a different style of connection similar to a Unifit.

One that we did to create a bathroom in an attic
View attachment 93506

Schematics from Duravit.. they look odd because I combined a couple of theirs.
View attachment 93507
Perfect, thank you! The next step was to determine slope and find a toilet C/L waste height to meet what I think now is 8' not 10' distance. Might have to add a branch vent too. I'm going back to measure anyway but wanted initial concept feedback. Duravits are really nice and $$$.
 

PtraP

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If your slope is a problem, note that IPC allows a slope of 1/8 inch (or more) per foot for 3 or 4 inch pipe.
Yes, in Michigan its 1/8" per foot for 3"-6" dia. pipe which will help with choosing other rear discharge toilet options.
 

wwhitney

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Yes, I've used a standard rear discharge floor mounted toilet to do exactly what you're describing
Can you clarify what is different internally between a rear discharge toilet and a wall mount toilet?

Because the latter with a wall elbow and require that its outlet be downward, at most 45 from plumb, which I understood to be necessary to finish creating the S curve geometry that causes the internal trap to siphon.

Thanks,
Wayne
 

John Gayewski

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The problem with rear outlet floor mount toilets is getting them installed with everything proper is a tough task. It's definitely possible but the tolerances are tight. They tend to leak, but can be done well.

Also upon first glance I don't think the Duravit toilet above is legal in the US. There is an internal baffle which I always understood to be illegal. The spec sheet shows there is a version that is upc listed, but the variant you'd need I'm not sure about.
 
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