What’s the purpose of this looped ABS pipe?

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wayovermyskis

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During my basement bath remodel I discovered this looped ABS pipe in the wall. Not sure where it starts, but it comes out of the floor and simply makes a loop. Issue is that it’s right near where the shower glass wall bracket will be screwed into the wall. I certainly don’t want to put a hole in the pipe, but moving it (near the floor, as the bracket is 8” above the bottom of the glass) is probably not an option for me. Initial thought was that it’s some sort of stand pipe, but I’m not certain. If it’s not necessary I could cut and cap it, but I don’t want to mess with anything that’s there for a purpose. House was built in 1984 and basement was finished sometime later. Shower plumbing, drain and fixtures are to the right of the pipe. Toilet is about four feet to the left on the same wall.
 

Stuff

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What is below it? I'm wondering if someone thought it would function as a fake vent.
 

hj

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It is someone's misguided attempt to make a "loop/yoke" vent, but failed miserably at it. It probably does function a little bit, under the right conditions.
 

hj

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At the end of the draining, where the vent is most important, the bottom section would NOT be full of water so air would be available to go to the top of the loop, and help prevent siphonage
 

Dana

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Perhaps it was meant to support the stud that was cut nearly completely? :)

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The way the basement is insulated with a studwall offset from the foundation keeps ground moisture from wicking into the fiberglass, which is OK from a moisture management point of view, but without a back-side air barrier the performance of the insulation probably isn't more than about R7 due to convection losses. It looks like you have maybe an inch, maybe two (?) between the stud edges and concrete at that location.

The wadded up batt all twisted up with wiring and pipe isn't providing any more function than the weird pipe sculpture, but hopefully the rest are installed a bit better than that.

Before finishing it off, see if you can't install some rigid foam between the studs & foundation as a capillary & thermal break. If you're rebuilding the studwall completely, the current IRC 2018 code minimum would be R10 continuous insulation, which can be 1.5" of rigid polyiso, or 2.5" of EPS. At 2" XPS would meet the letter of code, but is really only warranteed to R9 at that thickness over time.

If you don't have enough room to hit code-R with rigid foam on it's own, it would still make it with R11-R13 batts snugged right up to the foam. If they're not moldy reusing the existing batts would be fine.
 
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