I am surprised it is so hard to find a diagram or description of the proper way to rough in a bathtub spout. In case it makes any difference, the specific spout will be a Toto TS210EV with diverter.

At the bottom of the valve there is a 1/2 inch NPT male nipple (is that the right name?) so I expect to put in a descent pipe, 90° elbow and a nipple through the backerboard and tile.

But how far past the tile surface should the pipe go?

How small should the hole through the tile and backboard be?

How does one make sure the spout ends up vertical when fully screwed on?

  • Do you have access from the other side?
    – DMoore
    Apr 7 '14 at 22:33
  • @DMoore: Yes, I have access to both sides—it is all open. I have yet to complete two of the studs around the valve and whatever crossbraces might be needed.
    – wallyk
    Apr 7 '14 at 22:49
  • 2
    Take a look at this installation manual: totousa.com/Portals/0/ProductDownloads/…
    – pdd
    Apr 7 '14 at 23:23

According to the installation manual for the spout, the nipple for the spout should be installed a min of 3/8" to a max of 3/4" past the finished wall. There is a pipe adapter that you screw onto the nipple. The spout slides over this adaptor and is set in place with a set screw located on the bottom. This allows for the correct orientation of the spout.

The hole for the spout through the tile and back board should be about 1/4" to 1/2" larger than the nipple diameter allowing for an 1/8" to 1/4" gap between the nipple and the tile.

There should be installation instructions for the diverter valve that will include the vertical location of the valve relative to the spout, as well as the set back distance in the wall. There is usually a plastic over on the diverter valve that is to be set flush with the finished wall. This cover also provides the opening required for the valve. Check the diverter valve instructions.


Use a DROP-EAR elbow and provide some framing to screw it to, please.

How far past the tile surface - how deep is the spout when you get to threads? 1/2" US pipe thread is supposed to be tight when engaged 1/2", so add 1/2" to that. To provide room for another turn if needed and caulking, perhaps another 1/8" beyond THAT.

How small the hole - I like just big enough for the pipe, acceptable ranges from there up to just smaller than the back of the spout. Just enough for the pipe (or within 1/8") allows you to double up on caulking - caulk the hole around the pipe AND caulk the back of the spout (but leave a gap/weep hole under the bottom of the spout) - if there is a shower, this area is a prime one for leaks, so sealing it well is good.

How to get the spout vertical? As with anything else involving pipe threads and alignment, by judging whether you can get one more turn or not every time it's vertical, and stopping when you don't think you can. If you mis-judge, take it off, redope, and try again. IME, teflon dope beats teflon tape here...

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