Bathroom Rough-In Plumbing Cost: A Complete Guide

Quick Answer

Bathroom rough-in plumbing costs $1,500–$5,500 for a standard 3-fixture bath (toilet, sink, shower/tub). The wide range reflects fixture count, how far the new bathroom is from the main stack, and local labor rates.

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"Rough-in plumbing" refers to the first phase of bathroom construction — running all the supply and drain lines before the walls are closed. It's called rough-in because it's the rough structure of the plumbing system: pipes, vents, and drain stub-outs in the right locations, ready for fixtures to be connected later during trim-out.

Getting the rough-in right is more important than the finish work. Pipes in the wrong location, inadequate venting, or undersized drain lines cause problems that are expensive to fix once walls are closed.

What's Included in Rough-In Plumbing

A standard bathroom rough-in includes:

- Hot and cold supply lines to each fixture location

- Drain-waste-vent (DWV) lines connecting each fixture to the main stack

- Proper slope on all drain lines (typically ¼" per foot)

- Vent pipes extending through the roof to prevent siphoning

- Blocking in the walls for grab bars (if applicable)

- Shower pan or tub drain connection (if slab or subfloor work is needed)

It does not include fixture installation, finish valves, or connecting supply lines to fixtures — those happen during the trim-out phase, typically after drywall and tile.


Rough-In Cost by Fixture Count

The number of fixtures is the primary cost driver. Each additional fixture adds supply lines, a drain connection, and often additional venting:

- **Half bath (toilet + sink):** $1,200–$2,800

- **Full bath (toilet, sink, tub/shower):** $1,800–$4,500

- **Full bath with separate tub and shower:** $2,500–$6,000

- **Master bath (toilet, double sinks, separate tub, walk-in shower):** $3,500–$8,000

Use our [bathroom plumbing cost estimator](/plumbing-cost-estimator) to calculate your specific configuration.

What Drives the Cost Higher

**Distance from the main stack.** Every drain line needs to connect to the main vertical stack, which runs from basement to roof. A first-floor bathroom addition close to the stack is relatively straightforward. A second-floor addition or a bathroom on the opposite side of the house from the stack requires longer drain runs, more venting, and more labor.

**Slab vs. wood-frame construction.** First-floor additions over a concrete slab require breaking and repairing concrete to run drain lines — this alone can add $500–$1,500 to the project.

**Accessibility.** In new construction or gut renovations, everything is open and accessible. In a partial renovation where existing walls and floors are intact, the plumber needs to run pipes through finished spaces, which takes significantly more time.

**Regional labor rates.** Plumber hourly rates range from $65 in rural low-cost markets to $160 in premium urban markets. With 20–30 hours of labor for a typical rough-in, the rate difference alone can swing the total by $2,000–$2,800. The [plumbing cost estimator](/plumbing-cost-estimator) accounts for this regional difference.

**Permits and inspections.** New bathroom plumbing always requires a permit. Your plumber pulls the permit; expect $100–$400 for the permit fee plus one or two inspections (rough-in and final). Read our [plumbing permit guide](/blog/plumbing-permits-guide) for more on what inspectors check.

Timeline: How Long Does Rough-In Take?

A simple half-bath rough-in in a new addition takes 1–2 days. A full master bath with multiple fixtures, especially in a renovation with limited access, takes 3–5 days. The permit approval and inspection schedule often add 1–2 weeks to the overall project timeline.

Common Rough-In Mistakes

**Incorrect drain locations.** Fixture drain stub-outs must be precisely located to match the fixtures being installed. A toilet rough-in, for example, must center exactly 12 inches from the finished wall (the "rough-in distance"). If it's 11 or 13 inches, you either need a special toilet or the drain has to be moved — expensive.

**Inadequate venting.** Every drain needs venting to prevent siphoning (the sucking sound that also empties your P-traps, allowing sewer gas into the home). An improperly vented bathroom is a code violation and a health issue. This is one reason a licensed plumber is required for this work.

**Wrong pipe slope.** Drain lines need exactly ¼" drop per foot of horizontal run. Less than that and solids don't flow properly; more than that and liquid runs ahead of solids, leaving buildup behind.

Questions to Ask Your Plumber

Before hiring anyone for bathroom rough-in, get clear answers on these:

1. What is your rough-in distance for the toilet drain?

2. Will the work be done in a single mobilization, or will there be a rough-in visit and a trim-out visit?

3. Are permits and inspections included in your quote?

4. Who is responsible for concrete cutting if needed?

5. What's your process if the existing drain lines need resizing?