Plumbing Systems: Planning, Inspection, Installation, Alteration, Extension, Repair and Maintenance
What the exam tests
This domain tests planning and executing plumbing work: plan review, permits, rough-in and final inspection, installation, alteration, extension, repair, maintenance, and testing. Questions often ask for the next inspection step or the correct test.
Core rules
- Plan before cutting: fixture layout, fixture units, pipe sizes, slope, venting, cleanouts, and access. Verify existing capacity before adding fixtures.
- Obtain the permit and approved plans. Schedule rough-in inspection after framing and piping but before concealment. Final inspection follows fixture installation, testing, and restoration.
- Drainage and vent systems must be tested. Common tests are a water test with a 10 ft head or an air test at 5 psi for 15 minutes. Water supply is hydrostatically tested at 100 psi or working pressure, whichever is greater, for one hour.
- Alterations and extensions must meet current code. Repairs must restore safe function and cannot create a cross-connection, reduce venting, or leave an inaccessible cleanout.
- Maintenance includes freeze protection, leak repair, valve exercise, cleanout access, and backflow assembly testing.
Worked example
A remodel adds a basement lavatory. The existing 1 1/2 in drain has a trap arm 5 ft from the vent. The maximum for 1 1/2 in is 3 ft 6 in, so the plan must add a vent or relocate the fixture. The permit application shows the new drain, vent, and fixture-unit load; rough-in inspection verifies slope and venting; final inspection verifies trap seal, flow, and access.
Traps
Concealing before rough-in; skipping the drain and vent test; using the wrong test pressure; adding a fixture without checking existing vent and drain capacity; leaving a cleanout behind a finished wall; assuming maintenance work never needs a permit.