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Thread: Rough in plumbing clarification needed

  1. #1
    DIY Member techinstructor's Avatar
    Join Date
    Apr 2009
    North Carolina

    Question Rough in plumbing clarification needed

    We're getting ready to do the rough in plumbing on our new home. I'm not sure I completely understand just how much of the plumbing needs to be installed prior to the first "rough-in" inspection and testing.

    In the DWV system:
    Our county allows us to do a water test so that's what we are planning to do. I realize that each opening except for the highest one (on the roof) must be plugged:

    **Do we install the traps and the tail piece that will will connect to lav, sinks and tub?

    **Do we install the stand pipe for the washing machine?

    If not, at what point do we stop running pipe to the fixtures?

    As for the water distribution system:

    We are installing a Manabloc homerum system. The water supply line will come from the well, into the basement then into the pressure tank. From there it will go through 3 water filters (sediment, iron, and carbon). Then it goes to a tee with one line leading to the water heater and the other leading to the Manabloc. We have all the appliances here ready to go and the filters are mounted on the wall, but I was wondering if we should bypass any or all of these prior to the rough-in air pressure test.

    **Pressure tank
    **Water heater

    In other words, I'm not sure where the testing starts.

    Also I had planned to use the stop valves at each fixture as the plug on each line for the pressure test. Do the flexible the water supply lines for each fixture have to be included? Again, I need to know where it should stop.

    I know we have to have a tee with a pressure gauge installed for the test. Will someone tell me the name of the fitting that I need that would have the valve and connector to receive air from the compressor?

    Thanks a bunch.

  2. #2
    DIY Senior Member jastori's Avatar
    Join Date
    May 2008


    For us, the rough plumbing inspection would include all plumbing done prior to drywall - everything that is 'fixed'. For the supply, this typically means the piping stub outs from the wall, which are capped (typically no shut-off valves, definitely no flexible fixture supply lines). The DWV would include the washer stand pipe, the tub and shower traps (which are usually solvent welded in place), but not the lavatory trap (which is installed with the lav after final construction).

  3. #3
    In the Trades SacCity's Avatar
    Join Date
    Mar 2011
    Sacramento, CA


    The response above is perfect, basically want to test everything within the walls for a rough inspection
    Final inspection will cover the remainder. Use Caps and plugs for the rough inspection.
    Last edited by Terry; 04-06-2011 at 09:22 PM.

  4. #4
    Master Plumber-Gas Fitter shacko's Avatar
    Join Date
    Jan 2006
    Rosedale, Md


    If you are getting an inspection you should ask the inspector for your jurisdiction what he wants, inspections change depending on the location.

  5. #5
    DIY Member techinstructor's Avatar
    Join Date
    Apr 2009
    North Carolina


    Thanks for the advice. This helps. And I will definitely check with my inspector to verify local expectations. I think I understand how to do the DWV, but I'm still confused about where to start the water supply pressure test. I would appreciate knowing how it is typically done. I would guess that the pressure tank, water heater and filters would not be included in the test. I still don't know what kind of fitting I need to connect the air compressor to the system, nor do I know where the fitting would typically be installed.

    Thanks again.

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