Rough-In Inspection Readiness Walkthrough
Purpose
A failed rough-in inspection is rarely a hard technical problem. It is almost always something a crew could have found in twenty minutes with a tape and the code table open, and it costs a re-inspection fee, a lost day, and a slip that lands on every trade behind you. The second cost is worse: a shop that fails rough-ins gets scheduled last on the next job. This walkthrough runs the inspector's own checks before the call and leaves a dated record of the tests held, at what pressure, for how long, and who signed.
Scope
Covers the pre-inspection self-check and required tests for a plumbing rough-in on new construction or a permitted alteration, residential and light commercial: drain, waste and vent piping, water distribution, and fixture rough-in dimensions, from piping complete to the inspection call.
Does not cover the final or fixture-set inspection; gas piping tests, which have their own SOP, medium and duration; or backflow commissioning, which the backflow SOP owns. Whether a permit was required at all is an office question settled before the crew mobilizes.
Roles and responsibilities
| Role | What they own | The handoff |
|---|---|---|
| Office | Permit, the plan set on site, the AHJ checklist and adopted edition | Puts the edition and amendments in the job folder; the crew cannot check against a table it was never given |
| Lead installer | Every dimensional and code check, and both pressure tests | Signs the record before the call; the office does not place it on a verbal "we're ready" |
| Technician | Correcting what the walkthrough finds, and re-testing | Reports the corrected item and the re-test result, not just that it was fixed |
| PM or GC contact | The booking and the schedule impact of a fail | Receives the record before the call, so a fail is a shared surprise |
Procedure
Walk with the approved plan set and the jurisdiction's rough-in checklist, not from memory. Acceptance: stamped plan set on site, adopted code edition on the readiness record, local amendments listed. Wrong looks like checking against the code you learned in another state or cycle. Stop rule: if the edition or amendment list is unknown, or the set on site is not the stamped set, stop until the office supplies it - every table below is edition-specific, and the wrong table gives a confident pass and a real fail. Hazard: none.
Confirm the permit is posted, the scope matches what was built, and field changes are documented. Acceptance: permit card posted and legible, piping matching the approved plan, every deviation in writing with its reason. Wrong looks like a fixture relocated at the framer's request with nothing on paper. Stop rule: document the deviation before the call and send a material one back to the office for a revision; an inspector who finds an undisclosed change stops trusting everything else. Hazard: none physical.
Check slope on every horizontal drainage branch with a level, not by eye. Acceptance: fall at or above the minimum in IPC Table 704.1 as adopted - 1/4 in per foot for 2-1/2 in and smaller, 1/8 in per foot for 3 in through 6 in - over the full developed run, not at one hanger. Wrong looks like the right average slope with a sag in the middle, which drains today and holds solids in five years. Stop rule: any back-pitch is corrected before the call; an inspector's level finds it in ten seconds. Hazard: reaching an overhead run means a ladder, set and used per 29 CFR 1926.1053 on construction work; nobody stands on the top cap for one more joist bay.
Measure every trap arm's developed length against the table for its fixture drain size. Acceptance: trap weir to vent within the maximum in IPC Table 909.1 as adopted - 6 ft for a 1-1/2 in fixture drain, 8 ft for 2 in, 12 ft for 3 in. Wrong looks like a straight-line measurement across a corner instead of the developed length, which runs along the centerline through every fitting. Stop rule: an over-length trap arm is corrected by relocating the vent connection before drywall, because after drywall it is a demolition item. Hazard: that correction means solvent-cementing in place, and cement and primer release flammable vapor with an inhalation route, so ventilate, keep ignition sources away, and never do it head-first in an unventilated crawlspace.
Verify vent terminations, heights and clearances at the roof. Acceptance: each vent above the roof by the height your adopted edition of IPC 903 requires, above anticipated snow depth where that governs, and clear of doors, openable windows and air intakes by the distances that section sets. Wrong looks like a vent terminating a few inches from a dormer window. Stop rule: a termination that misses the clearance rule is relocated before the call, not argued at the inspection. Hazard: roof work under construction, so fall protection applies at the 6 ft trigger of 29 CFR 1926.501; the general industry trigger at 29 CFR 1910.28 is 4 ft, and the split is by activity, not building type.
Check support spacing and protection plates on every run. Acceptance: support intervals within IPC Table 308.5 as adopted, naming the material column you read, since copper, plastic DWV and PEX each get different intervals; steel shield plates wherever pipe passes a stud or plate with less than 1-1/2 in clearance to the face, per IPC 305.8. Wrong looks like reading the copper column for a PEX run, the most common miss on mixed-material work. Stop rule: an unsupported span or missing shield plate is corrected on the spot. Hazard: cutting or coring concrete releases respirable crystalline silica, an inhalation carcinogen governed by 29 CFR 1926.1153, controlled by water delivery or on-tool dust collection with respiratory protection where its Table 1 entry requires it; gloves and glasses do not address that route.
Check supply rough-in dimensions against the fixtures actually purchased. Acceptance: stub-out heights and offsets matching each fixture's own rough-in sheet, valves set to the depth their plaster ground marks call for against the planned finished wall thickness, blocking behind every valve and wall-mounted fixture. Wrong looks like a valve set for 1/2 in drywall on a wall that gets 1/2 in backer plus tile, leaving the trim ring proud and the stem short. Stop rule: a valve at the wrong depth is corrected before the tile, because after tile it is a tile demolition item the shop owns. Hazard: none beyond ordinary tool use; confirm the finished wall build-up with the GC in writing.
Set and hold the drainage test, and stand clear of the plugs. Acceptance: the test your jurisdiction requires under IPC 312 as adopted - water filled to at least a 10 ft head, or air at 5 psi - held at least 15 minutes with no drop in the gauge. Wrong looks like a tech watching a gauge for two minutes and calling it. Stop rule: any drop is a fail; find the leak, correct it, then run the full duration again from zero, because a partial re-test is not a test. Hazard: an air test stores real energy in a compressible medium and a plug that blows out becomes a projectile, so never exceed the plug's rated pressure, restrain it where the manufacturer calls for it, and keep everyone out of line with the open end and off the top of a plug under test.
Set and hold the water distribution test, and pick the medium deliberately. Acceptance: the test IPC 312.5 as adopted requires - water at the working pressure of the system, or air at 50 psi - held at least 15 minutes with no drop. Wrong looks like a system tested at whatever the street gave that morning, unrecorded. Stop rule: no drop is the acceptance, not a small drop blamed on temperature; if the gauge moves, find it. Hazard: 50 psi of stored air fires a fitting across a framed room if a joint lets go, where water releases almost none, which is why many shops test supply with water; with air, keep the crew clear of open ends and unbraced runs while pressurizing.
Run the shower pan or liner test where one is required. Acceptance: drain plugged, pan filled above the weep holes to the depth and duration your adopted edition and AHJ require, level marked and re-checked at the end. Wrong looks like a filled pan checked once at the start and once when somebody remembers. Stop rule: any drop in the marked level fails the pan, and it is repaired or replaced before tile, because a liner leak found after tile takes the whole shower out. Hazard: a filled pan upstairs is a real load on framing that may not be fully sheathed, so confirm the deck is supported before filling and never leave one overnight with other trades on site.
Photograph everything, complete the readiness record, then place the call. Acceptance: photographs of every wall and ceiling cavity showing pipe, supports, shield plates and valve depths, with a tape or marked stud in frame for scale, and the record signed by the lead installer. Wrong looks like calling first and photographing in a rush, with half the cavities missed. Stop rule: the call is not placed until the record is signed, and any area another trade has already covered is listed by location and reported to the GC in writing rather than signed for blind. Hazard: none; these photographs protect the shop when a screw finds a pipe two weeks after the pass.
The record this produces
The readiness record carries eleven entries: adopted edition and local amendments; permit and scope confirmation; slope result by branch; trap arm developed lengths; vent clearances; support and shield plate confirmation; the fixture dimension check with the models named; drainage test medium, pressure, duration and result; supply test medium, pressure, duration and result; pan test result where applicable; and the lead installer's signature with date and time.
Photographs attach to the same job record. The office decides from it whether to place the call, the GC learns of a fail before the inspector arrives rather than after, and the shop reads it months later, when a drywall screw punctures a supply line and the photograph of that cavity, shield plate visible, decides who pays.
One worked pass, including a failure
Two-story single-family, three bathrooms, permit issued under the adopted IPC edition with two local amendments in the job folder.
Step 3: the 3 in branch serving the second-floor bath group runs 18 ft developed. At 1/8 in per foot that needs 2-1/4 in of fall; measured fall is 2-1/2 in, no back-pitch along it. Passes.
Step 4 fails. The second-floor lavatory has a 1-1/2 in fixture drain, so the table gives a 6 ft maximum from trap weir to vent. Measured along the centerline the trap arm runs 5 ft 2 in to a 90, then 1 ft 8 in to the vent tee: 6 ft 10 in developed, over by 10 in. The straight-line distance across that corner would have looked fine. Stop rule taken: the vent connection is relocated before the call, the cement work done with the crawlspace hatch open, a fan running and ignition sources clear.
Step 8 has a false start. The DWV air test is set at 5 psi and drops to 3 psi in six minutes. That is a fail, and a partial re-test is not permitted, so the leak is found - a test cap on the kitchen stack not fully seated - and the full 15 minutes runs again from zero, holding 5 psi. Both attempts go on the record.
Step 9 uses water rather than air, the shop's standing choice on stored-energy grounds, held at working pressure for 15 minutes with no drop. Step 11 photographs every cavity with a tape in frame, the lead installer signs, and only then is the call placed. The inspection passes on the first visit.
References
- IPC in the edition your authority having jurisdiction has adopted, with its local amendments, which binds the work: 312 (tests and inspections), Table 704.1 (drainage slope), Table 909.1 (trap-to-vent distance by fixture drain size), Table 308.5 (support intervals by material), 305.8 (protection against physical damage), 903 (vent terminals).
- 29 CFR 1926.501 (6 ft construction fall protection trigger) and 29 CFR 1910.28 (4 ft general industry trigger), split by the activity performed.
- 29 CFR 1926.1153 (respirable crystalline silica in construction, including the Table 1 control and respiratory entries for concrete cutting and coring) and 29 CFR 1926.1053 (ladders in construction).
- Fixture and valve rough-in sheets, and test plug rated pressures and restraint requirements, from their manufacturers.