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I have gutted my bathroom down to the studs, and I want to put a shower mixing valve directly where the red X is. The problem is that board outlined in red is load bearing for the staircase landing behind that wall.

I assume I can't cut out a section of that board to fit a valve and reframe the wall without causing structural issues. Is it possible I am overlooking or overthinking this solution?

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  • How much are you thinking of cutting out? Holes/notches up to a certain percentage(25/30%?) are usually allowed. Cutting out a whole section will be a no and in need of an engineer.
    – crip659
    Commented Jan 18 at 15:45
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    Move it up ~6 inches or down ~8 inches is the obvious solution, rather than fixating on "must be exactly this height"
    – Ecnerwal
    Commented Jan 18 at 15:49
  • It would need to be a huge hole, over 50% to fit. Moving it up or down would put the valve at a super awkward position either too high or too low. The top of that board is 48in form the ground.
    – ACD
    Commented Jan 18 at 15:55
  • There's nothing crazy going on at the top of the stud above your X is there? My assumption is maybe a bit of weight from a single floor, but with floor joists running parallel to the wall that carries your hypothetical valve. Is that about right?
    – popham
    Commented Jan 18 at 19:28
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    @FreeMan - Here in Europe we prefer that too. And I dislike that. :D
    – Vilx-
    Commented Jan 19 at 14:47

4 Answers 4

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There are a couple of options that don't involve a structural engineer and major work.

If this is exactly where you want to put the shower, the easiest path forward is to frame out the wall with another layer of studs. You will avoid the huge structural headache that it would cause to try to place a shower valve where that structure is. The downside, of course, is that you will lose 3.5" of the room to your extra layer of studs.

The alternate option is to rearrange your bathroom layout to avoid this structural challenge.

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    Depending on the depth of the shower valve, the frame out could even be done with 2x2 or with 2x4 ripped to any thickness. Just enough to clear the valve assembly.
    – FreeMan
    Commented Jan 18 at 16:07
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    Oh yes, a standard Moen for instance would work with a 2.5" rough out I think.
    – KMJ
    Commented Jan 18 at 16:10
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    Another option is a "smart" shower control. These use a small control panel on the shower wall, and a valve unit installed in the wall close by. The water is piped to the shower head(s). No traditional shower valves are used. One example: shop.moen.com/collections/smart-shower
    – Mark
    Commented Jan 18 at 16:25
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    @Mark ah, something new that I could plug in my Home Assistant so that the family is further entertained by not only "usually" having lights, but now also "usually" having hot water (in that case the "usually" would fall outside the morning or evening for even more fun). But seriously - very good idea.
    – WoJ
    Commented Jan 19 at 13:17
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    glad I'm not the only one experiencing "usually", @WoJ... :)
    – FreeMan
    Commented Jan 19 at 14:24
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That's effectively a rim joist and you can cut it out such that what remains is equivalent to the studs above and below it. It was only installed as a matter of convenience for the carpenter and isn't required in any way to remain solid.

You want to retain these things as you cut your opening:

  • Pass-through bearing between the upper and lower studs. You could offset the block for the stud near the X a few inches without concern.

  • Support for the subfloor on the stair landing. You don't want a completely unsupported stretch of more than say 12".

  • Support for the joists that apparently intersect this rim, as indicated by the stacks of nail heads. 2" of bearing on the lower wall plate is adequate. It does not need the rim joist for support.

In this case I would cut out a 12" section of just the 2x10 rim, centered on your valve location. Leave the common joist behind intact. From there, assess interference from what's behind and to the sides and ask a new question if necessary.

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  • Interpreting this answer (esp reading the nail heads) I think a good plan might be: 1) Install a double layer of 1/2 inch cement board here (and equivalent thickness drywall along this entire wall), then notch (don't remove) just enough space for the valve and pipes in this location. You won't need much depth into the board if you double the wall thickness. Find a valve, get hold of its documentation to find out its tolerance from front of tile to front of the wood. Remember the valve is usually installed on a block between studs.
    – jay613
    Commented Jan 18 at 18:48
  • Ok so calling this out as a rim joist is helping me out here. So you are saying I could cut out the section in red and just add two mini studs in blue and I would not violate anything? imgur.com/a/FwgBkYg
    – ACD
    Commented Jan 18 at 19:08
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    Absolute minimum joist bearing is 1-1/2". There's probably a half inch of joist that could be removed by-the-book if the 1-1/2" from the rim board alone is insufficient. And technically there should be blocking from at least one side of the joist to brace it against rotation at the end there, but I feel like a donkey for even mentioning it. I would probably chop it back to the flanking joists and use the chopped material as blocking recessed along the back of the top and bottom plates.
    – popham
    Commented Jan 18 at 19:54
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    I agree. I don't consider blocking a concern assuming that the joist is locked in with the subfloor. This just isn't a high load situation where it's a critical failure point.
    – isherwood
    Commented Jan 18 at 19:56
  • @isherwood A picture would be great cause I am not sure what is meant by pass-through.
    – ACD
    Commented Jan 18 at 21:19
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If it's important for you to put the shower right there, consider a surface mounted shower panel instead of an in-wall system. They are insanely easy to install, you get way more bang for the buck and they are easy to repair and replace without breaking tiles. Here is an example of a cheap one on Amazon so you know what I'm talking about but you can find better ones from plumbing suppliers. It's an especially good fit for your situation.

To cut a huge hole in that board you would have to know exactly how it's being used on the other side. If it's holding up a couple of stair risers or joists supporting the steps, as long as those stair supports transfer into what remains of that board and from there onto the studs beneath, you might be okay. That board is not like a joist, it is supported everywhere. But you can't know that without knowing what's on the other side. [Edit: If you want to go this route, see @isherwood's more thorough answer]

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Another possible solution is to use an external shower valve. These are widely used in Europe and are not unattractive. The hot and cold pipes emerge from the wall at a prescribed spacing of 15 cm (6 in) and the shower mixing valve attaches to them. The valves have adjusting connectors to perfectly line up with the supply pipes.

One huge advantage of these is that replacement of the valve is fully extermal to the wall. These come in thermostatic mixing types.

You could even have the supply pipes emerge from the wall low, turn 90 deg up to place you want the valve then 90 deg out and mount the valve. All this exposed piping could be designed to be attractive.

One company sells "bespoke" shower plumbing valves out of copper pipe mounted externally on the control wall. These, though, might not have a thermostatic mixing valve.

EDIT

The prescribed separation of the two supply pipes that I have seen is 15 cm. You would have to dertemine how close to this the pipes must be located. The external thermostatic mixing valves I have seen have a clever means of adjusting the spacing on the valve connections, which might give as much as 1 cm of adjustment (or more) but that would have to be paid attention to. In the US the normal spacing of the old two valve tub/shower lines was 8 in, so if any plumber is engaged he would have to be informed on what was being used.

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