Plumbing Rough-In Inspection Checklist
For: Plumbing inspectors, master plumbers, GC supervisors
Plumbing rough-in inspection has two failure modes: things that leak and things that don't drain. Both get exponentially expensive after drywall. This checklist covers DWV slopes, water test pressure, support spacing, and the small items (cleanouts, vent terminations, isolation valves) that inspectors specifically check.
References: UPC 2024 · IPC 2024 (where adopted) · Local amendments
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DWV (Drain, Waste, Vent)
Horizontal drain slope — 1/4 in per ft for ≤2.5 in pipe; 1/8 in per ft for ≥3 in
UPC 708.0
No reverse-grade segments anywhere in run
Cleanouts at every change of direction >45° + at base of every stack
Cleanouts accessible (12 in clearance min)
Vent terminations ≥10 ft from openings, ≥6 in above roof
UPC 906.0
P-traps within 24 in of fixture (waste arm length)
UPC 1002.1
No S-traps anywhere (illegal in modern code)
Water Distribution
Pipe materials match spec (PEX, copper, CPVC) — no mixed-system issues
Hot and cold lines spaced or insulated to prevent heat transfer
Isolation valves at every fixture, every branch from main
Water heater T&P discharge piped to drain, full size, no traps
Expansion tank installed if required by water district
Hose bibbs equipped with vacuum breakers
UPC 603.4.7
Support & Penetrations
Pipe support spacing — typically every 4 ft horizontal copper, 32 in PEX
UPC Table 313.3
No ferrous straps in contact with copper (galvanic action)
Sleeves at all penetrations through concrete + fire-rated walls
Fire-rated penetrations sealed per UL system
IBC 714
Pressure & Air Test
Water lines tested at 1.5× working pressure (typ. 100 psi for 15 min minimum)
DWV air test at 5 psi for 15 min (no pressure loss)
Inspector witnesses test, signs documentation with date + time
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