Above floor plumbing help


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Old 09-10-21, 11:57 AM
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Above floor plumbing help


Adding a half bath to laundry room as pictured below. On a slab foundation and don’t want to cut up the slab if at all avoidable. Will need a macerating/pumping toilet anyways because the drain on this side of house isn’t big enough for a toilet drain.

my question is how to get the plumbing along the wall to the sink (it is an exterior wall). The supply lines is on and that macerating unit will be on the same wall as the w/d. If I’m reading codes correctly, I cannot run 1.5 inch pipe through the 2x4 studs on an exterior wall (or I can run through 2 sets of studs if doubled up.

Can I run 1.25 in pipe from the sink instead of 1.5 inch so we can run it through the studs? If not and I have to run it inside the room do you have any suggestions on how to hide the pipe?

Is it OK to run the supply line through the exterior wall? It’ll be about 4 feet at most and the wall is protected from wind. We can insulate the pipe in addition to the insulation.

any other suggestions?
 
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Old 09-10-21, 03:29 PM
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I try to never run water supply lines in an exterior wall. It's just tempting Mother Nature to freeze those pipes during an unusually cold winter. In your situation I would box out an area to run your sink water and drain lines. It's not load bearing so you don't even need studs if you build it like a cabinet or wooden box.
 
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Old 09-13-21, 10:36 AM
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I don't think 1.25" pipe can be used as a drain anywhere in a standard plumbing system. 1.5" is the minimum.

I wouldn't run 1.25" through a load bearing wall anyway if at all possible. Instead, I would build out that wall (on the right) using 2x2s plus a 1/2" plywood "shim". Run the 2x2's horizontally and use the resulting space to run the drain pipe (and probably the supply piping too. You could also build out the wall from the floor up to 36" or so, using 2x4s for the piping, then have a little shelf next to the toilet. You'll end up losing 2 - 3.5" of the room, but I think that's a better solution that cutting into the exterior wall.
 
 

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