Bath spout rough-in/Nipple or Sweat

Discussion in 'Shower & bathtub Forum & Blog' started by 46&2, Sep 8, 2009.

  1. 46&2

    46&2 New Member

    Messages:
    7
    Location:
    North Carolina
    Hi y'all, this is my first post on this forum; I've found tons of great info here in the past....so thank you!

    I'm re-modeling my master bath. I have all of my new valves and trim, and I'm working on roughing-in the Tub/Shower valve, and I have a few questions.

    First off I need a bit of clarification on my installation instructions.

    The rough-in instructions have this note:

    "Use only 1/2″ pipe (galvanized steel) or 1/2″ (5/8″ OD) copper pipe (type
    L or M) between the valve and bath spout. Using other materials may cause
    backpressure and result in water flowing from the showerhead and bath spout at the same time."

    So basically; use only "standard" metal plumbing and maintain at least 1/2" ID all the way from the valve to the spout.. but what if I use brass or bronze elbows? I believe that this note is intended to address restriction/flow rather than the actual metal that is being used...right?

    There is also this:
    "Locate the valve and install 1/2" piping and elbows to bath and shower outlets. Do not use multiple elbows on the spout outlet."

    Is the "Spout Outlet" referring ONLY to the "Bath Outlet" and NOT the "Shower Outlet"? I can not seem to find the proper nomenclature for the parts of the "system" and I intend to use more than one elbow between the valve and the "Shower Outlet" because I need to plumb around a recessed shelf that is going in the shower wall.

    Now on to the real questions.

    The install instructions call for 1/2" sweat to 1/2" Female NPT drop ear elbows to be secured to bracing in the wall, and then threaded nipples are used to connect the "Bath Spout" and "Shower Head" to the elbows.
    Can I instead use 1/2" sweat to 1/2" sweat drop ear elbows in the wall with a straight coupler attached to a copper 1/2" sweat to 1/2" Male NPT adapter protruding through the finished wall, and thread my Spout and shower head directly to it? My escutcheons will fit over the adapters.

    The way I see it, this will eliminate one of the two threaded joints, and the most critical one at that; the one in the wall, and allow me to more easily meet the 1-1/4" protrusion of the fitting from the finished wall with out jerking around with nipples.

    I personally think this is a better approach in general, however I am concerned about twisting the copper when threading on the spout and head.
    I am using L-Type pipe and it seems to me that the coupler would only serve to strengthen the pipe's longitudinal axis; besides that, the total length of the piece from threads to elbow will only be about 3". In my experience I'd be hard pressed to damage that setup unless excessive force was used. so what do you think?

    Also, what is commonly used as bracing for the elbows in 2x4 walls? I will barely have a 1/2" of space between the ears on the elbow and the wall board. If I use the 1/2" sweat/sweat drop ear elbows, I can flip them over so that the ears are horizontal (on the bottom), and install a 2x4 brace between the studs (2" side up) directly under the elbow; the ears will end up centered on the 2" side of the 2x4 providing lots of material to fasten it to. Good?

    I would really appreciate hearing your thoughts on this!

    Thanks,
    Matt
  2. Runs with bison

    Runs with bison New Member

    Messages:
    891
    Location:
    Midwest
    Matt,

    I'm not sure, but to make that shower vertical smoother perhaps the detour could use 45's instead of 90's? This should make it better at self-draining (no additional horizontal) and result in a little over half as much equivalent length count, yet have the same number of fittings as the 90's.

    Depending on how you do that detour around the shelf you might be able to reduce the extra fitting count by 1 also.
  3. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,293
    Location:
    Cave Creek, Arizona
    valve

    The valve to spout is the only critical line, because it is the one which will create back pressure and force water up the shower riser. A threaded drop ear elbow will give you much more latitude when installing the spout because you can choose the correct length nipple to screw the spout onto. The way you describe will also work as long as you cut the copper tubing at the proper distance from the wall. A coupling is just two additional joints which could leak and does not add anything to the job.
  4. 46&2

    46&2 New Member

    Messages:
    7
    Location:
    North Carolina
    Thanks R /w B,
    I measured it up last night and I can use 45's for the shower route, so based on HJ's feedback, thats the plan for the top half.
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,824
    Location:
    New England
    As noted, the only critical connection is the valve to spout. If the water can't flow freely, it will act like you've partially pulled the diverter, and you could get water out the showerhead while filling the tub. No need for anything special to the showerhead. Brass, if you wish to use it, would be fine. I'd prefer not to use galvanized for anything related to potable water. Whether you use a threaded connection for the spout depends entirely on the type of spout you have. Some screw on, some push on a straight pipe then you tighten a set screw to hold it in place.
  6. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,293
    Location:
    Cave Creek, Arizona
    shower

    You could use a bunch of 90 elbows on the shower riser and it would not affect the flow in the slightest.
  7. 46&2

    46&2 New Member

    Messages:
    7
    Location:
    North Carolina
    OK, thanks guys, Iv'e got it pretty much worked out.
    Now my questions are:
    1. Is there a standardized method of measuring nipples? Seems like with a dry fit there is about 1/2" of thread used per end; this is probably a bit less with thread sealant...yes, 3/8" maybe? With the spouts that I have I will need to be pretty precise, the escutcheons are attached to the end of the spouts and the spout is threaded onto the nipple until the escutcheon gasket is snug against the wall so I don't think there is a whole lot of room to play with maybe 3/32" or 1 full turn of the spout, roughly.

    2. Would you use a piece of 1/2" board to secure the ell, or notch out a 2x4, or doesn't it matter?

    Thanks,
    Matt
  8. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,293
    Location:
    Cave Creek, Arizona
    threads

    Pipe sealant will allow the thread to engage further than with a dry fit, not less. And any way you can secure the pipe will be okay.
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