I am ripping off my shower kit and the wall. Before demo, I took picture of the back of the shower fiberglass wall:

enter image description here

I plan to install tile. What happen next is to put drywall and then hardie board and seal.

My question is:

How to make sure the check valve mechanism flushed to the back and ensure the handle can screw in and flushed in the front of the tile?

So I assume I need to put the white piece behind the wall.

But old shower wall has different thickness which is much thinner than the new drywall + hardie backing board + thinset + tile which could be 1.5" thick.

I tried to "dry fit" everything first and need to figure out how this might look like or if I need to do some washer or different type of mechanism...

enter image description here

Any idea?


Here is the full view:

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I can "move" the plumbing in and out. It's quite flexible:

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  • New shower valves come with a template/plate that shows you where the finished wall surface should be in relation to the valve. Without that plate (which is specific by brand and model of valve) all you can do is "dry fit" your trim with actual or substitute materials that approximate your wall thickness, then mark the valve. Do not be surprised if you find you will need to re-solder to position the valve correctly. Commented Jan 13, 2019 at 13:21
  • My question is that if I am replacing the shower head and handle + valve, while installing drywall, do I need to take into consideration of the handle and valve connection? Or can it be an after thought? Because I have a drywall team doing drywall and they need to know if they have to make a big hole or small hole.
    – HP.
    Commented Jan 14, 2019 at 9:34
  • The position of the valve (as it relates to the finished wall surface) should not be an "after thought" because it is important. Your trim (face plate, escutcheon, handles, etc.) may not install correctly if improperly placed. The riser pipe and shower arm elbow must also align with the outlet on the new valve. Commented Jan 17, 2019 at 3:02
  • So how is it supposed to be done?
    – HP.
    Commented Jan 19, 2019 at 7:19
  • I have updated with additional photos. I can move the entire mechanism. So I am wondering if it's OK just like that...
    – HP.
    Commented Jan 20, 2019 at 6:34

1 Answer 1


Before I address your question, I just want to say drywall isn't necessary. Attach your cement board directly to the studs but put a plastic sheet in between them. Then tile on the cement board.

Now for the valve placement, I wouldn't leave it dangling like this. Once I figured out the correct location and depth, I put a wood block behind it, secure it to the studs and attach the pipe to wood block with brackets.

For the depth of the valve, be super careful and triple measure things. Best would be to buy your valve, cartridge, shower trim, tiles, and cement board and have them in hand. Make a little cement board template w/ the hole, attach your tiles w/ double sided tape, and put the trim on. Account for the thinset as well.

The trim usually has wiggle room, and you can be off +/- 1/4". Usually, when it comes to this part, I take my sweet time and take a look at it multiple times and try to imagine what can go wrong. Once you close the walls, it's too late.

One last tip, make sure the valve is perpendicular to the wall. Else the trim will not be flush to the tiles around its entire circumference.

  • I plan to use RedGard. Would plastic water proof sheet is better / easier? The valve has been dangling from the previous shower. So that is my question: Would dangling giving me flexibility? What is the cost of having it dangling?
    – HP.
    Commented Jan 24, 2019 at 6:08
  • The problem with it not being secured is the pipe moving back and forth. Depending on what/where it rubs it could cause noise when expanding/contractor or worse case cause a rupture at some point. You shouldn't be pulling on the pipe for the flexibility. This is copper. It is fantastic but can kink just from looking at it wrong. :) Commented Jan 24, 2019 at 14:47
  • This is a good answer, a few pointers. Looks like there's a tab on the front you can use to fasten the valve to the wall, one screw through that hole should be sufficient to hold it. I would use the advice above to set your depth and err on the side of too deep into the wall. If you don't have enough adjustment in the plate to make up for the slight differential you can remove the mounting screw and slide a shim behind the valve. Commented Jan 24, 2019 at 15:27
  • In addition to what @MicahMontoya said, if you don't secure your plumbing, when you want to put the trim on, it will be harder as the valve will retract into the walls.
    – Quoc Vu
    Commented Jan 25, 2019 at 3:26
  • Regarding Redgard, the construction of showers using a topical membrane is quite different than the traditional type (which I was assuming in my first reply). That probably deserves its own thread. But just want to say with elastomeric liquid membranes, while it looks easy (e.g. just paint Redgard on), there are a lot of details you need to take care, thus it can be deceptive.
    – Quoc Vu
    Commented Jan 25, 2019 at 3:42

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