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Trade walkthroughs

How to inspect plumbing rough-in

Plumbing rough-in is where a slope that is an eighth of an inch off, or a joint that was never tested, becomes a callback you cannot reach. This walkthrough covers the waste, vent and water piping in the order it goes together, and it centers on the one thing that carries the day — the pressure or water test the piping has to hold before anyone covers it.

For the plumbing foreman verifying their own rough-in, or the GC's superintendent confirming it is ready before slab pour, insulation or drywall.

Step by step

  1. Confirm the layout matches the drawings

    Walk the waste, vent and water lines against the plans and the fixture rough-in dimensions. Stub-outs should land where the fixtures and equipment will, at the right heights and centerlines, before anything is furred or boarded.

  2. Check DWV slope and venting

    Drain lines should fall at the required grade — enough to carry solids, not so much that water outruns them — and every trap should be vented. Sight the runs and measure where it matters; a flat spot in a waste line is a lifelong problem.

  3. Verify the DWV test is holding

    The waste and vent system should be under a water or air test with a gauge you can photograph, held for the required period with no drop. Observe and record the test — the plumber runs it, you document that it held before cover.

  4. Pressure-test the water piping

    Hot and cold supply piping should be under test at the required pressure, isolated from fixtures, holding steady on the gauge. Check joints and fittings for weeping while it sits under pressure.

  5. Inspect supports, hangers and slope on suspended runs

    Piping should be supported at the required spacing with hangers rated for the pipe, with no sag between supports and no dissimilar-metal contact left to corrode. Confirm expansion is accommodated on long runs.

  6. Check pipe protection and penetrations

    Where pipe passes through a plate or stud, look for the nail plate or sleeve that keeps a fastener out of it. Every penetration of a rated wall or floor gets logged for firestopping, and pipe in exterior walls gets its insulation checked.

  7. Photograph the system before it is covered

    Capture the tested system with its gauge, the slope where it is critical, and each penetration, tied to the room and line. This pre-cover set is your answer when a leak shows up downstream of a joint you can no longer see.

What gets missed

  • A DWV run with a belly or flat spot that passes a glance but never fully drains.
  • Covering piping on a verbal 'it held' with no photographed gauge and no recorded test duration.
  • Traps left unvented, or a vent that never ties back above the flood rim.
  • Missing nail plates on supply lines run through studs, waiting for a drywall screw.
  • Stub-outs roughed to the wrong height or centerline, discovered only when the fixtures will not land.

Questions people ask

Do I still need the jurisdiction's rough-in plumbing inspection?
Yes. Your walk gets the work right and documented; the AHJ's rough-in inspection is the required sign-off that lets you pour the slab or close the wall over it.
What test should be on the system at rough-in?
The DWV and water piping should each be under the water or air test the code and AHJ require, held with no pressure drop — observe it holding and photograph the gauge rather than taking it on faith.

Standards behind it

Terms worth knowing

Checklists that make this a one-tap job

Free, field-ready checklists, each with the photo every item needs before it can be submitted.

Plumbing Rough-in· PlumbingPlumbing rough-in inspection checklistUnderground and in-wall piping, slopes and supports before pressure testing9 items14 photosPlumbing rough-inRough-in plumbing inspection checklistSupply, DWV, slope, supports and the pressure test that proves it.13 items24 photosPlumbing Pre-cover· PlumbingPlumbing pre-cover inspection checklistThe hold-point walk before slabs are poured and walls are closed6 items10 photosPlumbing Final· PlumbingPlumbing final inspection checklistFixtures, supplies, traps and water heater set and operating before turnover9 items12 photos
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Related guides

Reading the steps is one thing. Proving you walked them is the job.

RTI holds the submit button until every mandatory item is answered and the photos are attached, then chains the record so it can be proven untouched later.

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