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Curious Hole in Floor

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kok328

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Moved in about 12yrs. ago and there was always a spot in the basement floor that was framed out with 2x4 and filled loosely with dirt. The hole has a 2" pvc pipe sticking out of it. Come to find out it was 2x8 and there was no bottom to it, all dirt. half the framing was about floor level.
I dug it out to see what was up, backfilled it with sand and plan to mix up some concrete to fill it in.
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1. What is this pipe intended for?
2. Why is it not finished into the cement like the other pipes?
 

oldognewtrick

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I can visualize rough in's for a sink, toilet and shower drain. "Maybe" it was left like that for flexibility of drain location for a shower base. Or it could be they just ran out of concrete...😉
 

zannej

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I agree with the other posts. Looks like a plumbing rough-in for future work & they left it open for a tub or shower drain & give more flexibility for positioning.
 

Sparky617

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I have a plumbing rough in just like this in my basement. My assumption is the large boxed out hole is to allow you to put in a trap for the shower or tub. The toilet wouldn't have a trap and the bowl itself has the trap,, and the sink trap would go right under the sink so the hole in the concrete is not needed.

I'm about ready to start finishing my basement so I plan to put that into action.
 

kok328

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The main waste line comes from the other side of the basement down the wall and into the floor. It's the one with the cleanout cap on it. Don't know how deep into the floor it goes but, it would seem like a pretty shallow tub trap. I was planning on a raised floor for the additional restroom but, never realized that the tub would need some clearance for a trap. I don't know about a toilet because of needing a vent stack to the roof, unless I can tie into an existing stack a few feet away.

Anyway; question answered, thanks guys.
 

zannej

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kok328, Keep in mind that if your tub has an overflow you need clearance for the overflow as well. In most common configuration you have a pipe at the overflow that goes down to a sanitary tee. The side inlet of the tee is for the tub drain. There is a tub "shoe" that sits under the tub drain and goes to that tee. Under that there's a P-trap.

There is also a direct drain configuration where the P-trap is below the sanitary tee directly below the tub drain and the overflow drain has a 90° elbow leading to the side inlet of the tee. Whichever of the pipes has to go to the side of the tee needs to slope downward a bit to allow gravity to do it's work.
 
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