Trade Coordination, Inspections & Pressure Testing Through Closeout
Welcome
Hello, and welcome. This is Super Structures General Contractors — a national general contractor headquartered in Powhatan, Virginia — here to help you and your clients build something that lasts. We're glad you're with us, and we look forward to connecting with you.
Alright, Trade Coordination, Inspections & Pressure Testing Through Closeout. Don't let the plain title fool you. Here's the part that actually matters on the job: Gravity pipe gets the right-of-way and the inspection sequence sets the schedule, so coordinate your routing before the other trades hang their work and show up to every inspection with the test on the gauge and the paperwork in hand. Learn it well and you'll be the sub the superintendent schedules around with confidence instead of the one who holds up drywall.
This is the lesson about everyone else on the job.
Coordinating with the other trades
Plumbing goes in first in the rough-in sequence for a reason: it is the biggest pipe and the only one that must slope. Gravity wins in ceiling coordination; ducts and conduit route around the sanitary and storm lines. That only works if you are in the coordination meeting before anything is hung, with your routing marked up and your elevations known.
- Framing — walk the plumbing walls with the framer before sheathing. The IRC limits notching and boring: bearing studs may be notched 25 percent and bored 40 percent (60 percent if doubled), nonbearing studs 40 and 60 percent, and joists bored no more than one-third of their depth with holes at least 2 inches from the edges and never notched in the middle third. Pipe within 1-1/4 inches of the framing face gets a steel nail plate at least 1/16 inch thick extending 2 inches past the member.
- Structure — nothing goes through a beam, girder, or truss without the engineer's written approval. On concrete decks, hanger inserts go in before the pour.
- Electrical — no piping in the dedicated space above a panel (the panel's footprint from the floor to 6 feet above it under NEC 110.26).
- HVAC — duct mains and your 4-inch sanitary cannot occupy the same elevation; settle it on paper. Plastic DWV in a return-air plenum must be listed for plenums under the IMC.
- Fire protection — penetrations through rated walls and floors get a listed firestop system, and plastic pipe through a rated assembly gets an intumescent collar or wrap.
- Finishes — valve and niche heights come from the tile layout; sink and dishwasher locations come from the cabinet shop drawings, not the floor plan.
The inspection sequence
A typical residential job inspects underground before backfill and slab, rough-in or top-out after test and before insulation and drywall, the shower pan before tile, the gas rough and gas final before the meter is released, and final with every fixture set and running. Commercial work adds above-ceiling and cover inspections by area, backflow test reports, and the fire marshal's walk. Each one is a gate.
Be ready before you call: permit card posted, approved drawings on site, the test on and holding when the inspector arrives, access clear, listings visible on the materials, and the local checklist walked by you first. Call a day or two ahead and tell the superintendent the date so insulators and drywallers plan around it.
Pressure tests by system
- DWV — a 10-foot head of water for 15 minutes with no drop, filled from the highest opening and tested in sections with plugs, or 5 psi air for 15 minutes where allowed and the pipe manufacturer permits it.
- Water — the working pressure of the system, or an air test of at least 50 psi for nonplastic piping, held 15 minutes under the IPC; many jurisdictions call for 100 psi water, and plastic is water-tested only. Isolate anything not rated for the test: relief valves, mixing valves, PRVs, heaters, and backflow assemblies.
- Fuel gas — the IFGC requires not less than 1-1/2 times the working pressure and never less than 3 psig, held at least 10 minutes; many authorities ask for 10 to 15 psi for 15 minutes or longer. The gauge range may not exceed five times the test pressure. Isolate appliances and regulators, which are not rated for test pressure, and soap every joint.
- Shower liners — plug the drain and hold 2 inches of water at the threshold for 15 minutes (IPC 312.9), with the weep holes clear.
Flushing, disinfection, and closeout
Flush the water system before trim with aerators off, then disinfect potable piping as the IPC requires, following AWWA C651 or the local method: 50 ppm chlorine for 24 hours or 200 ppm for 3 hours, and flush to background. Start the heater and lift the relief valve, set every shower limit stop with a thermometer, test the backflow assemblies and file the reports, tag valves and furnish the valve chart, and hand over the record drawings, O&M manuals, warranties, and owner training. Insulation goes on after the test passes, never before. Then final inspection, punch list, and the certificate of occupancy.
Going Deeper (Intermediate)
The schedule runs on inspections, so manage it like money. Know the authority's lead time and cutoff hour, keep a test log with gauge photos stamped with date and permit number, and never let a trade behind you start on a wall that has not passed. A failed inspection costs a reinspection fee, a return trip, idle drywallers, and your reputation with the superintendent. Many authorities now allow virtual inspections by video for certain tests; ask, do not assume.
Advanced / Pro-Level
On commercial projects the finish line is commissioning: functional tests of the recirculation system, booster pumps, master mixing valves, sewage ejectors, grease interceptors, and backflow assemblies, witnessed and documented for the owner's commissioning agent. Medical gas systems get ASSE 6020 inspection and ASSE 6030 verification before use. Pros build the closeout binder from day one, because test reports, submittals, and as-builts are easier to file in week two than to reconstruct in month ten.
Practice Challenge
It is Thursday. Your top-out test passed with the superintendent watching, drywall is scheduled for Monday, and the earliest inspection slot is Tuesday. The superintendent wants to hang board Monday and "leave the plumbing walls open." What do you do? (Answer: do not let unpassed work be concealed. Ask the authority for a cancellation slot or a virtual inspection; if neither, propose in writing that drywall start Monday only on ceilings and walls with no piping, leaving the plumbing walls open until the inspector signs. The risk of covering is a failed cover inspection, removed drywall, reinspection fees, and the schedule you were trying to save.)
In Practice
A plumber who sits in the coordination meeting, walks the framer through the plumbing walls, logs every test with a photo, and calls the inspector a day early is the sub the superintendent trusts with the critical path. A plumber who discovers the duct in the ceiling after the sanitary is hung and calls the inspection the morning it is needed becomes the reason the job is late.
Common Mistakes to Avoid
- Hanging gravity pipe without a coordinated elevation and finding the duct later
- Letting drywall or insulation cover work that has not passed inspection
- Testing with relief valves, mixing valves, or regulators still in the line
- Using a gauge whose range is far too large for the test pressure
- Treating closeout documents as something to assemble after the final
Takeaway: Gravity pipe gets the right-of-way and the inspection sequence sets the schedule, so coordinate your routing before the other trades hang their work and show up to every inspection with the test on the gauge and the paperwork in hand.
Educational content only — not plumbing design, engineering, or code advice, and not a substitute for apprenticeship training, licensure, or a licensed plumbing professional. Code sections cited are from model codes; editions, amendments, and adoption vary by jurisdiction. Follow the plumbing, fuel gas, and energy codes as adopted where you work, the manufacturer's installation instructions, and your company's safety procedures.