Move shower drain/P-trap back 2"

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Don_P

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I had a plumber come and do the rough plumbing of my basement bathroom. It passed inspection and then we poured concrete over it. Once we had everything framed up I noticed when measuring off the bottom plate of framing to the center of my drain I'm sitting at 13 15/16". The shower we picked out calls for a center drain location of 15 15/16".

I need to move the entire drain and P-trap directly backwards 2". I did chip away the concrete around the drain and in front of it to get access to the pipe.

I currently cut it back 2" and put in a fernco coupling. The drain in now in the perfect spot and the shower base fits. I'm just concerned because 1. I think when I cut the pipes it wasn't a perfectly straight cut and when joining together with the coupling I'm pretty sure their is a small gap between the pipes inside the fitting. 2. I'm not sure if I maintained the correct pitch and height when I added on the P-trap portion and tightened down the coupling. I made reference marks and used a laser so I'm hoping all is well. I did also pack gravel underneath and around pipes, so it shouldn't be able to move at all.

Before covering my hole back in concrete, what's the best method for moving this drain back 2" and preventing the pieces from moving or losing their pitch? The fernco coupling I used? a slip joint? a slip joint and re pipe the p trap?

Hope I did my best to explain this.





 

Don_P

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any information would be great. I would like to get this covered in concrete and my base installed soon.
 

John Gayewski

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A good way to do this is with a template. Make a template the exact dimensions of your shower base (unless you have the actual shower base) and pipe it so the riser pits perfectly in the hole. Use hard pvc dwv fittings and don't use fernco's or no hubs. Use a coupling if need be.

Also you don't need to put the concrete around the pipe. You can leave a square out around the riser so it has some flex, or an 8" pipe as a concrete form to keep some open space around the riser. Generally for a shower we leave the trap out and put a plastic box down on the ground for the concrete to be poured around.
 

Don_P

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A good way to do this is with a template. Make a template the exact dimensions of your shower base (unless you have the actual shower base) and pipe it so the riser pits perfectly in the hole. Use hard pvc dwv fittings and don't use fernco's or no hubs. Use a coupling if need be.

Also you don't need to put the concrete around the pipe. You can leave a square out around the riser so it has some flex, or an 8" pipe as a concrete form to keep some open space around the riser. Generally for a shower we leave the trap out and put a plastic box down on the ground for the concrete to be poured around.
I had to move the entire drain back 2 inches to hit the center of my shower drain. I did a test fit and it fits perfectly.
I used a Fernco fitting though, is this not allowed?

I used a laser to make sure the middle of the pipe hit my measurement and a torpedo level to keep it plum. I then have it all supported by gravel.

Should I take out the fernco fitting and use a split coupling and redo the P trap assembly completely?

 
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Jeff H Young

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A good way to do this is with a template. Make a template the exact dimensions of your shower base (unless you have the actual shower base) and pipe it so the riser pits perfectly in the hole. Use hard pvc dwv fittings and don't use fernco's or no hubs. Use a coupling if need be.

Also you don't need to put the concrete around the pipe. You can leave a square out around the riser so it has some flex, or an 8" pipe as a concrete form to keep some open space around the riser. Generally for a shower we leave the trap out and put a plastic box down on the ground for the concrete to be poured around.

john I really like the template Idea youve mentioned it before. i mark center lines on floor but eye balling those can be iffy
 

John Gayewski

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Fernco's are generally fine underground. We avoid them if you don't need them. I don't see why a glue couping isn't an easy use here. If you want to keep the fernco go for it. It's just not as good as a solid glued joint.
 

Don_P

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Fernco's are generally fine underground. We avoid them if you don't need them. I don't see why a glue couping isn't an easy use here. If you want to keep the fernco go for it. It's just not as good as a solid glued joint.
So basically, pull out the fernco, clean up the pipe and glue in the slip joint coupling?

If that's all it takes it sounds too easy and would be a much better choice I believe. I thought I would have to glue on a slip joint and then remake the entire p trap assembly.

I did save enough pipe from both ends where I could probably just glue in a slip joint coupling and be done
 

Jeff H Young

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I just didnt want to chastise you for it but I see no reason for the fernco other than at this point you are done
 

Don_P

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I just didnt want to chastise you for it but I see no reason for the fernco other than at this point you are done
I appreciate the help! I will get a coupling and repair it correctly, as I don't want any issues once it's covered up again.

I just search Menards website and they have a few different types of couplings. Could you perhaps attach a picture or link to the best coupling to use in my instance so I don't buy the wrong type. I'm assuming since one end of the pipe is free and I can place it anywhere needed and remove if need be, that a standard coupling with a stop would work?? Or is without a stop better?

Access is kinda tight, but I should be able to dig out enough gravel to get a coupling on it.
 

Don_P

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Looks like I might need to redo the P Trap assembly anyways, as the shower drain riser isn't plumb. 1 way is perfect, other way is probably 3/8-1/2" out of plumb. I'm going to assume I want the riser to be as plumb and flat as possible? I'll be using a no caulk shower drain.



 
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