Centered drain - do I have to? [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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08-05-2004, 12:11 AM
I was reading clipper's postings on her trials with a shower, and everyone seemed adamant that the drain had to be centered...I have a similar issue, and I don't want to center my drain either. I have a 36"x36" 3-wall shower with the drain about centered right to left, but only about 9-12" from the back wall. The shower is leaking and ugly and I plan to replace it, but I am reluctant to move the drain because it seems like too much work.

Here are the issues:
1) The drain is in (or under) about an 8-10" existing concrete slab
2) The drain is 1 1/2", not 2" (which I understand to be code from reading here), and I fear if I open it up an inspector will make me replace the whole thing (I am doing a larger downstairs remodel and this tiny bathroom is only part of it. I have a permit for other parts of the project).
3) If I do have to make it 2", I will probably have to break out about 4 feet of the family room slab, since the drain line leaves the shower and connects to a bigger drain in the middle of the family room.
4) From what I can see, the vent currently goes near the center of the shower, so I will need to move that also, as well as a drain for the sink. Let me see if I can you face the shower, the shower drain line goes left, connecting to a larger drain under the family room. Once past the trap (which is going left), the drain wyes with the vent, which cuts back right past my off-center drain (near the center of the shower, near as I can tell) and connects to a vent system on the right side of the shower. After the vent, there is a T with a 1 1/2" drain coming from the sink, and then the drain disappears under the family room slab.
5) The corner of the shower is a structural post, and I am currently planning on pouring a footing for the post that will be 24"x24"x18" deep on Friday (the hole is how I realized the depth of the slab and saw the configuration of the drains.)

So, moving the drain feels difficult, especially if I have to change it to 2". What is the consequence of leaving it where it is? Will 1 1/2" work?


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08-05-2004, 05:50 AM
The tiling consequences of not moving the drain will be a relatively steep slope between the drain and the nearest wall. This is because you want to slope the floor 1/4" per foot and you also want a level perimeter so the tiles will look better. Thus, the slope at the near edge will be much more than the slope to the farthest wall. Hope I 'splained that well enough. :D

I am curious about the drain fitting you have now. Is it a floor drain or a shower drain fitting? The difference is that a shower drain fitting has a flange and clamping ring for attaching the membrane (liner) and a floor drain does not. Shower drains will also be made for 2 inch pipe. Using a smaller pipe will mean that, aside from code issues, your shower will drain slower, possibly slower than the water comes in (expecially as it gunks up with soap scum and hair).

08-05-2004, 07:32 AM
Welcome, AG. :)

What Bob said.

Further, if you have to pass code and the inspector is gonna gig you on the size of the drain, he's already got cause to do that; you're already changing that drain plumbing, ergo the new drain needs to meet code.

I seriously doubt that your slab is more than four inches thick in the field (everything that is not a grade beam). If you're only seeing eight or ten inches on the perimeter beam, they might have made it even thinner than that, but we'll hope not. It's really not usually that difficult to break out enough concrete to more the drain to the center of an old tub installation, and it's done all the time.

If you're on a permit, and if you're doing the work yourself, it's usually best to get the inspector involved early and find out what he's gonna approve and not. It's one of the few times when getting permission is actually easier than getting forgiveness. As Bob points out, you're gonna hafta change that drain fixture no matter what, so might as well chip a little more and do the thing right. You might find that you can (must?) re'route that vent while you're at it. I'm not sure, from your description, exactly what you've got under there, but I bet you can deal with it once you break out some concrete.

Easy for me to say? Yep, but you know you gotta do it. :)

My opinion; worth price charged.

08-05-2004, 08:41 AM
Thanks. I am not sure on the drain -- it looks like a shower drain, and narrows from 2" to 1 1/2" about 6 inches below the surface of the existing tile. It is pretty gunked up -- for all I know, it is the cause of the seepage that comes from the shower today.

08-05-2004, 08:44 AM
Actually, now that I think about it, it could be a floor drain. I can't see if there is a flange or not since the old tile is still there. Also, all the previous work was done in 1960, so I am not sure what they used then for drains. I think it did have a permit back then, so 1 1/2" must have been acceptable in the past...

John Bridge
08-05-2004, 06:54 PM
Hi AG, :)

I'm at a loss as to what you might have going on in that shower. If you are definitely going to re-do it, why not break it out so we can see what's going on? :)

08-06-2004, 12:08 PM
It will take a while, but I will. In my plan for the remodel, I said "existing bathroom to remain" so my plan is to get the rough inspection done before I do anything.

Thanks for a great forum.