Shower Drain not plumb and floor installation [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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05-23-2012, 11:04 PM
Hi all,

I'm new to this forum, and I've just torn down my master bathroom. The house has galvanized steel drain system, and I removed the last piece of pipe from the shower P-trap and replaced it with a PVC male adapter, which I'd like to join to the Kerdi-drain. The problem is that the drain inlet seems to be not plumb. I'm thinking to heat-bend the short PVC pipe from the adapter to the kerdi-drain to make sure that it's level with the floor. Is that a good idea? Is there any other suggestion? I'm not confident enough to cut the line and replace it with ABS or PVC.

Also, I'd like to tile the bathroom floor, and I currently have 2x6 T&G subfloor. I plan to add 3/4" AC plywood on top of it before putting Ditra and tile it. How does that sound?

Thanks in advance.

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Tool Guy - Kg
05-23-2012, 11:27 PM
Hi Jerry! Welcome!

So, you're saying you still have the old iron p-trap? If so, how old is it? Iron p-traps corrode and are a common source of problems. And the most opportune time to replace them is when the shower is torn out and you have easy access. They are not difficult to replace once you have access to them. It typically involves severing the p-trap completely (downstream from the p-trap on the horizontal portion of the drain pipe) and joining new PVC to it via a clamped on Fernco fitting (rubber fitting outfitted with a stainless steel band and band clamps). I think replacing it requires not much more than patience and a little knowledge. It's not a big deal.

About your floor structure. We need to know about your joist sizes, O.C. spacing, and unsupported span distance to give you more meaningful info.


06-06-2012, 11:20 PM
Thanks ToolGuy.

Sorry for the late reply. Just got back from vacation.

I'll check out my floor structure and get back here. Do I need to flatten the 2X6 T&G subfloor first? I lay down the plywood, and it's obvious that it's not even, since I can rock the plywood corner-to-corner a little bit, probably there is 1/16 - 1/8, I'm not sure.

06-07-2012, 01:39 PM
Thanks Bob,

The steel pipe has gone, and I've got a PVC male male adaptor in. The tilt is ~3deg (3" in 48").

Regarding my floor structure: It's 48" OC joist (I'm in CA), and I'm guessing the joist size is about 6" wide, and I'm not sure the thickness.

The subfloor had water damage before, and I've closed the subfloor, except for the drain hole. There are some low-points on the sub-floor, should I fill those? if so, with what kind of material? I presume that SLC does not work on T&G subfloor? I've never sanded boards before, but is it fine to use tools like the oscilllating tool (e.g. Dremel)?

06-17-2012, 06:05 PM
Thanks for the suggestion Bob,

How about I put the 3/4" plywood directly? I can add more layer(s) later on, or is the 1/2" plywood necessary? There is certainly a sagging of the T&G plank between the joists. The bathroom is very small 4'x8.2' only.

06-17-2012, 06:10 PM
There is certainly a sagging of the T&G plank between the joists.If that's the case, I would definitely remove the board subflooring, bring the joist tops into plane, and start with a first layer of 3/4" Plywood subflooring.

My opinion; worth price charged.

06-20-2012, 11:27 PM
Hi Bob,

So, I've put 3/4" plywood and screwed it on the subfloor. The first 15" from the outside facing wall, the floor slopes down by 3/16" within the first 15". The floor then flattens out afterward. I plan to put Kerdi shower tray within 32" from this wall. So in total, for the shower area (32"), the difference in height is 3/16". The floor is relatively flat after that, the undulation is < 1/8" measured using my 4' straight edge. Any advise?

CX, thanks for the suggestion, but the flooring starts from the foundation, which means that I have to tear down the wall to put the subflooring. The first joist is 4' away from the wall, and I can see only 2 joists within the bathroom. The next joist would be in the living room, which I wouldn't like to tear down.