shower drainage - S-Trap?


Old 10-18-16, 09:58 AM
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shower drainage - S-Trap?


I have an issue with my new drainage. I am working with 2x6 floor joists, and I therefore cannot install a proper 2" p-trap to drain the shower.

If I were to raise my shower base by two inches, would I then be permitted to install an S-trap, and then a 90 degree elbow to tie in to my 2" line, set at the highest point under the subfloor?

My drawing sucks, but illustrates the point I want to make. Top of the S-trap above subfloor but below shower base, and a 90 degree elbow to go under subfloor.


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Old 10-19-16, 10:34 AM
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You can't make an S-trap. You'll have issues with draining and the trap getting sucked dry.

Instead, can you just raise the shower floor like you have pictured, drain into a P trap, then come out just below the subfloor?
Old 10-19-16, 04:52 PM
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Look at the profile of a p trap. You will note the exit is lower and should be adaptable to your situation.
Old 10-21-16, 03:57 PM
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I think I fould a solution, involving raising the shower floor a bit.

I will use a P-trap, give it about a foot of pipe, then a 45 degree into my wye that taps into my main line... all on 2" line. How does that sound to you all?

Chandler : I have a 2" P-trap, and it measures a total of 7 1/2" from bottom to top of the exit. My floor joists being 2x6 (really 5 1/2" depth), it is not possible to use a 2" P-trap without either kludging the plumbing, or raising the shower floor.

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