Slab-on-Grade - Plumbing Exterior Wall

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readytowork

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I am add two bedrooms and bathrooms onto my home. The bathrooms will be stacked one on top of the other with the fixtures lined up like this: sink, toilet, tub/shower combo. Same thing on first and second floor. The plumbing and DWV will all be in the exterior wall (6" studs). I believe I have figured out how to layout the DWV lines BUT then I realized that the exterior wall would have a 2' deep by 18 inch wide footer (a/k/a footing, beam) in addition to the 5" slab. If I plumb the DWV like I planned, they all come together into one trunk that is running the same direction as the exterior wall that they are on (see attached image as a general example). This would mean that the trunk is running through the footing.

Question 1: Is it a bad idea / flat wrong to have your main drain running through a footer (footing, beam)?

Question 2: What is the right way to handle this issue?

Option 1: I suppose I could have everything slope away from the exterior wall (either in (which would be under the slab) or out (which would be under the yard). Is that what I should do? If so, how far away from the footer must I be?

Option 2: I suppose I could rotate the main trunk 90 degrees and have it exit the exterior wall where the toilet stack is. Then, I would have to angle the drains for the sinks/tubs to meet it.

Option 3: Another option I am missing?

Question 3: No matter the design, the trunk still needs to come out somehow. Can it come through the footer or must I trench under it to some depth? If it can go through it, what are the requirements for going through the footer (e.g., what type of sleeve, at what depth in the footer, rebar spacing, etc.)?

Question 4: No matter the design for the main trunk, the drains and vents still need to go into the footer (and likely exit the footer) to meet the trunk. Are there any rules for locating these without weakening the slab footer?

Question 5: Is there a particular part of a the common codes that covers the "rules" for running pipes/tubes in footers?

As you can see, I'm stumped by the prospect of running the DWV through the footer because I'm worried about messing up that important structural feature of the home. I'd appreciate any advice you all have in doing this properly. Please speak to me like I'm new, because I am.
drain.JPG
 

readytowork

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I failed to mention that this is a monolithic pour, so we'll be pouring cement for both the 2 ft deep x 1.5 ft wide footings at the same time that we pour the 5" slab.
 

Jeff H Young

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many details , but a drain line crossing a footing can be done but a drain running through a footing is the extreme just running like in the bottom of a footing or suspended by tie wire is what would get you trouble.
change your layout where drain pipe is perpendicular to footings not paraelle unless its 3 or 4 foot away
 

readytowork

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Thank you. So I can run the pipe through the footing. Is it better to dig way down and run it under the footing (assuming I can) so that it's not "stuck" in the slab for future maintenance purposes?
 

Jeff H Young

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the way I understand it you may run the pipe accros a footing perpendicular at 90 degrees or at an angle not less than 45 degrees . I think if you have depth below the footing is better than through it.
following the footing in the bottom would likely cause a issue with inspector Ive seen it with electrical conduit and seen it being torn out and reworked.
 
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