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P-trap under a clawfoot tub

bluedog225

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Jan 31, 2012
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3,276
Location
Texas
There’s no room for a P-trap under my claw foot tub. It’s on a slab. I’m guessing my two options are put the tub on a platform (2x6 vertical plus 2x6 horizontal buys me 7”), or cut a hole in the floor and put the P-trap under the slab.

A third option is to dig a tunnel and get to it from there.

None of this sounds appealing.

Am I missing anything?

Thanks
 
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75gmck25

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Jul 21, 2014
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Location
Alexandria, VA
Once you get the trap installed, do you have a path for the horizontal drain pipe to run over a drainage location?

I have seen installations where they cut a hole in the slab to allow for the tub P-trap. If you line the hole in the slab with heavy plastic and then add gravel to support the trap, it should not be an issue unless you have a high water table that pushes water up through the hole.

For my basement shower we did the same type of rough-in and had the drain pipe come up in the middle of the opening. This gave us flexibility in the exact location of the P-trap and and made it easier to connect it to the shower base. Otherwise it would have taken a lot of very careful measurement and allowance for finished drywall thickness, shower base dimensions, etc. to make the shower base align exactly with a fixed pipe coming out of a cement slab. IIRC, using that cutout in the slab was exactly what the shower pan directions suggested.
 

Codyboy

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Jan 31, 2019
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S.E. TEXAS
All tub traps I've seen are in/under the slab. Unless this is a brand new location for a tub it should already have a trap.
 
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bluedog225

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Remodel in 1995. Didn’t know better and improvised. Horizontal line with a riser loop and an air admittance valve. Worked fine all this time. Though it drains slow. Started leaking and I’m trying to decide whether to redo the same or tear it up and do it properly. It’s going to be a big project.

Thanks
 
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bluedog225

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As in post 5. Drop from the drain, horizontal line, vertical rise, then loop down through slab. Horizontal section holds water.
 
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cmandp

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Dec 22, 2011
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New Jersey
The corrugated tubing is not code compliant and just not a good idea. The trap also needs a 2" seal height minimum so that typical suction on the DMV system cannot empty the trap of water and cause a sewer gas leak.

I would say plumb it the right way. Cut the slab, install p-trap. You have to pay to play so to speak. I'm not going to say that it's easy.
 

gahrajmahal

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Dec 12, 2008
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Location
Cincinnati, Ohio
Hey. Look at that.

I owe you a drink or something.

Thanks!

If I had a dollar for every time I got an answer from the GJ, I’d be able to hire a plumber!

The flex line is a nice touch.

Chef's kiss of homeowner hacks

I didn’t say the Google results were good ones, just someone somewhere has a solution besides chopping out the floor.

I put an IKEA sink in my son’s downstairs bath and it has a super shallow p-trap design exactly like that and it seems to work Ok. I’d just be concerned with a proper vent. Slow drains from a tub are bad. Makes the tub scummy and need frequent scrubbing.
 

NORTON'S SHOP

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Dec 30, 2010
Messages
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Location
Upper Midwest
Remodel in 1995. Didn’t know better and improvised. Horizontal line with a riser loop and an air admittance valve. Worked fine all this time. Though it drains slow. Started leaking and I’m trying to decide whether to redo the same or tear it up and do it properly. It’s going to be a big project.

Thanks
Usually; in my experiences; improvising ends up costing me in the end. I guess you're finding that out now.
 
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