# Hole in Slab Around Shower Drain... Fill it??



## creiteljorge (Feb 4, 2013)

Hi all! My name is Christopher and this is my first post so let me know if I'm missing anything important.

The attached pictures are of the slab under my stand-up shower. I'm doing a remodel and when I removed the old preformed tub I found this hole.

I'm working to put in a tile shower with tiled floor. I'm going to use the Schluter Kerdi Shower System with the Kerdi Shower Tray. Makes sense to me that I must have some support under said tray.

A local contractor told me to get the plumbing ready for the tray and then backfill the hole with floor mud.

Is this the right way to do this? Also, is there a reason why the hole was left in the first place?

Thanks in advance!


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## joecaption (Nov 30, 2011)

Anyone else think copper drain lines is a very bad idea.
Anytime I've seen it, it's leaking even when it's not in direct contact with concrete or soil.
Most often it's back filled with sand and a thin layer of concrete layed over it with some form of protection around the pipe where it goes through the concrete.


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## oh'mike (Sep 18, 2009)

Typically that is packed with gravel or sand---then covered with a thin skin of concrete or deck mud as the pan is installed---

You want some wiggle room when you install the pan----don't concrete that in before the pan is installed---the drain set goes below the floor level--so leave an open area to receive the drain set.

You may wish to change the P-trap and riser to PVC---most modern drain sets are not designed for copper.


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## creiteljorge (Feb 4, 2013)

Thanks, guys.

So I could cut out the p-trap/riser and adapt to PVC at that point? I know the Kerdi System calls for a PVC drain but I was just going to adapt to PVC on the riser. Why would a PVC trap/riser be better?

I've heard mention of a 4" PVC "sleeve" that I could put around the riser for protection before I backfill. That way the entire drain pipe is not closely encased in sand/cement.


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## oh'mike (Sep 18, 2009)

So often the P-trap is corroded and will grab hair----so I always replace them---

The sleeve you are talking about is made of foam---yes they are handy---but if you leave that open--packed with sand---you will have some wiggle room-----just add a layer of deck mud as you are setting the pan/drain and you will still be able to adjust the drain enough for a good allignment with the drain set---


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## Alan (Apr 12, 2006)

Looks like you have a 1.5" drain there. You need to change it to 2".


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## jagans (Oct 21, 2012)

At least the guys that poured your floor were nice enough to give you some working room there. Judging by the amount of copper oxide I see on your copper pipes, I agree with Joe. Go PVC DWV. Wheres the vent?


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## Alan (Apr 12, 2006)

jagans said:


> Wheres the vent?


Judging by the angle of the pipe, and the crack in the slab, i'd guess it's just barely out of the picture there.

:thumbup:


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## creiteljorge (Feb 4, 2013)

Alan - I noticed some other posts mentioning that same thing regarding drain diameter. I will have to take a measurement of the drain pipe when I get home. I will update then.

The vent is about 3-4 feet outside of the picture in the direction that the pipe runs. As far as I can tell the vent is shared with the dual sinks. The bathroom only has one vent for sure.

oh'mike - So as long as the mud is still somewhat viscous I will be able to wiggle the drain while I'm setting the pan. The deck mud will still cure after it is covered up?


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## creiteljorge (Feb 4, 2013)

Update - drain pipe is 1-1/2". There even used to be a standup shower there! Does this mean removing the drain back until it ties into a larger section of the drain system? I suppose it would be cutting a pretty big corner if I just adapted the Kerdi Drain to 1-1/2"...


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## Alan (Apr 12, 2006)

Yes, you're going to have to tie into a larger line somewhere. Not a bad idea anyway to get some of that copper out from under the slab.


Besides, you'll probably have a hard time adapting the 2" (more than likely abs or pvc) kerdi drain to 1-1/2" copper. The O.D. of the two materials is vastly different.

Besides all of that, once you get the shower built up, if you've got it plumbed with a 1-1/2" drain, you really won't be happy with it.


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## oh'mike (Sep 18, 2009)

The deck mud will cure fine under your pan----


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