New Construction Plumbing: The 3 Phases, Cost, and Timeline
New construction plumbing runs in three phases across the build: underground groundwork before the slab pours, rough-in after framing, and trim-out after drywall and finishes. Budget roughly $4.50 per square foot for rough-in and $600 to $1,600 per installed fixture. Most 2,000 square foot homes with two or three baths land between $12,000 and $20,000, depending on region and code.
What are the three phases of new construction plumbing?
New construction plumbing splits into groundwork, rough-in, and trim-out. Groundwork sets buried drains and the water service before the concrete pours. Rough-in runs supply, waste, and vent lines inside framed walls. Trim-out connects fixtures at the end. Each phase carries its own inspection and its own share of the total cost.
The table below maps each phase to what the plumber does, when it happens in the build, the inspection that gates it, and roughly how much of the plumbing budget it eats.
| Phase | What the plumber does | When in the build | Inspection | Cost share |
|---|---|---|---|---|
| Groundwork (underground) | Sets the sewer or septic lateral, water service line, and under-slab drain and vent stub-ups | Before the slab pours, or under the first floor on a crawlspace or basement | Underground/slab inspection with a water test | ~15% to 25% |
| Rough-in (top-out) | Runs supply, drain, waste, and vent piping in the walls; sets tub and shower valves and fixture stub-outs; adds gas lines | After framing, before insulation and drywall | Rough-in inspection, often combined with electrical and mechanical | ~45% to 55% |
| Trim-out (finish) | Sets and connects toilets, sinks, tubs, faucets, the water heater, and appliances; tests pressure and drainage | After paint and flooring, near completion | Final plumbing inspection | ~25% to 35% |
The middle phase, rough-in, is the biggest and the most detailed. The dedicated rough-in plumbing stage guide covers pipe sizing, DWV layout, and stub-out dimensions in depth, so this page stays on the whole-build view.
The new construction plumbing sequence, step by step
Plumbing does not happen all at once. It threads through the build in a fixed order, waiting on the foundation and framing crews and then handing off to insulation and drywall. Getting the sequence right is what keeps a passed inspection from becoming a torn-out wall later.
- Plans and permits: the plumber reviews the fixture layout and pulls the plumbing permit before any pipe goes in the ground.
- Groundwork: buried drains, vents, and the water service go in and get a water test.
- Slab pour or foundation: concrete covers the approved under-slab piping.
- Framing: the carpentry crew frames walls, floors, and the roof.
- Rough-in (top-out): supply, waste, and vent lines run through the open framing, with valves and stub-outs set.
- Rough-in inspection: the inspector checks the open walls before they close.
- Insulation and drywall: the walls close over the approved rough-in.
- Trim-out: fixtures, faucets, the water heater, and appliances get set and connected after paint and flooring.
- Final inspection and pressure test: the system is tested and signed off before occupancy.
Room-level work happens inside the rough-in step. The bathroom rough-in and kitchen rough-in guides break down the pipe sizes and spacing for those rooms specifically.
How much does new construction plumbing cost?
New construction plumbing for a typical 2,000 square foot home with two or three bathrooms runs $12,000 to $20,000 all in. Estimators price it two ways: per fixture and per square foot. Both should land in the same range on a normal build. If they diverge sharply, the layout is unusual or the quote is off.
| Method | Basis | Typical range | 2,000 sq ft example |
|---|---|---|---|
| Per fixture | Each plumbed point: toilet, sink, tub, shower, water heater, dishwasher, washer box, hose bibs, ice maker | $600 to $1,600 installed (rough-in plus trim) | 12 to 15 fixtures = ~$9,000 to $18,000 |
| Per square foot | Rough-in labor and material only | ~$4.50/sq ft (range $4 to $10) | 2,000 sq ft = ~$9,000 rough-in |
| Whole-house total | Groundwork plus rough-in plus trim plus fixtures | Varies by baths and finish level | $12,000 to $20,000 (2 to 3 bath) |
To use the per-fixture model, count every point that needs water or drainage, then multiply by $600 to $1,600 based on finish grade. Pipe material moves the number: PEX runs about $0.40 to $2 per foot, while copper runs $2 to $8 per foot, so a full copper supply system can add thousands. Fixture quality, extra baths, and long runs to a far corner of the house push toward the top of each range. These figures are national averages and vary by region and local code.
How long does new construction plumbing take?
Plumbing spreads across weeks of the build even though the plumber only works a handful of days. Underground groundwork takes one to two days. Rough-in runs about three to five days for a 2,000 to 2,500 square foot home with a crew of two or three, per NAHB figures. Trim-out adds one to three days near the end.
The gaps between phases are set by the other trades, not the plumber. After groundwork, the plumber waits on the slab pour. After rough-in passes inspection, the crew waits on insulation, drywall, paint, and flooring before returning for trim-out. Multiple stories, extra bathrooms, or a failed inspection can each add days to the plumbing timeline.
Who coordinates the plumber during a new build?
The general contractor owns the schedule and slots the plumber into the build sequence, because plumbing has to interlock with the foundation, framing, and drywall crews. The plumber pulls the plumbing permit, does the work, and calls in each inspection. On an owner-build, you or your project manager take on that coordination.
Miscoordination is where cost and delay creep in. If drywall goes up before the rough-in inspection, or the slab pours over untested under-slab drains, the work gets opened back up at someone’s expense. A clear handoff between the GC and the plumber at each phase keeps the build moving and the inspections clean. In many areas the permit must be posted on site and the inspector given notice before each phase closes.
Frequently asked questions
What are the three stages of new construction plumbing?
New construction plumbing has three stages: groundwork (underground drains and the water service, set before the slab pours), rough-in after framing (supply, drain, waste, and vent lines run inside the walls), and trim-out after drywall and finishes (setting fixtures, faucets, the water heater, and appliances). Each stage ends with an inspection before the next trade continues.
How long does plumbing rough-in take on a new house?
Underground groundwork usually takes one to two days. Above-ground rough-in runs about three to five days for a 2,000 to 2,500 square foot home with a crew of two or three plumbers, per NAHB estimates. Trim-out adds one to three days near the end. Complex layouts, extra baths, or code delays can extend each phase.
How much does it cost to plumb a new 2,000 square foot house?
Plumbing a new 2,000 square foot house with two or three bathrooms usually costs $12,000 to $20,000. Rough-in runs near $4.50 per square foot, and installed fixtures average $600 to $1,600 each. Pipe choice matters: PEX runs about $0.40 to $2 per foot, copper $2 to $8 per foot. Prices vary by region and local code.
When does the plumber come during new construction?
The plumber arrives at least twice before finishing. The first visit sets underground drains and the water service before the concrete slab pours or under the first floor. The second visit is rough-in, after framing and before insulation and drywall. The plumber returns a third time for trim-out once paint and flooring are done.
Who schedules the plumber, the builder or me?
The general contractor schedules and coordinates the plumber against the build sequence, because plumbing has to interlock with the foundation, framing, and drywall crews. The plumber pulls the plumbing permit, does the work, and calls in inspections. On an owner-build, you or your project manager handle that coordination and permit timing directly.
What inspections does new construction plumbing require?
New construction plumbing needs at least two inspections, sometimes three. An underground or slab inspection with a water test comes before the pour. A rough-in inspection follows framing, often combined with electrical and mechanical. A final inspection checks fixtures, pressure, and function before occupancy. Requirements vary by state and local code.
Last reviewed: September 2026.