Plumbing Scope of Work Checklist: Pipe, Fixtures, and Trenches (CSI 22 00 00)

In construction, water is the enemy. It destroys foundations, ruins drywall, and causes mold. Therefore, the Plumbing trade is one of the highest liability contracts a General Contractor signs.

The friction in plumbing contracts usually comes from the “gray areas”—where the pipe hits the dirt, or where the valve meets the tile. If these interfaces aren’t defined, you will be paying for Change Orders to connect the dots.

To ensure your plumbing bids are watertight, use this Plumbing Scope of Work Checklist (aligned with CSI Division 22).

The Standard Inclusions (The “Must Haves”)

A complete plumbing bid is usually broken into three distinct phases. Your scope must cover all of them:

• Ground Rough (Under-slab): Installing sanitary waste and water supply lines before the concrete is poured.
• Top-Out (In-wall): Running stacks, vents, and water lines inside the walls/ceiling before drywall.
• Trim-Out (Finish): Setting toilets, sinks, faucets, and trim plates after paint/tile.
• Gas Piping: Sizing and running gas lines to all appliances (Range, Furnace, Water Heater, Fireplace).
• Testing: Pressure testing of all lines for inspection approval.

The “Scope Gaps” (Where You Lose Money)

1. The “5-Foot Line” (Site Utilities)

Who connects the house sewer to the street sewer?

• The Trap: The Site Excavator stops 5 feet from the building. The Plumber stops 5 feet from the building. You have a 10-foot gap with no pipe.
• The Fix: Explicitly state: “Plumber to connect to site utilities at [specific location].” Or, define that the Plumber is responsible for everything “Inside the building footprint.”

2. Trenching and Backfill

Plumbers are expensive pipe-fitters, not cheap laborers. They hate digging.

• The Trap: The bid says “Excavation by Others.” You have to hire a laborer to hand-dig a trench inside the foundation for them.
• The Fix: Require the Plumber to “Perform all interior trenching and backfill” for their own lines. (Note: They usually won’t compact it, so assign compaction to the Concrete sub).

3. Fixtures vs. Rough-in Valves (The “Owner Supplied” Myth)

The client wants to buy their own fancy gold shower faucet online.

• The Trap: The client buys the trim (the handle), but not the mixing valve (the brass part inside the wall). The Plumber arrives to do the rough-in and has no valve to install.
• The Fix: Even if fixtures are “Owner Supplied,” require the Plumber to “Supply and Install all rough-in valves compatible with Owner selected trim.”

4. Fire Stopping & Caulking

• The Trap: The plumber drills holes through your fire-rated floor assembly. They run the pipe and leave. The inspector fails you for holes in the fire barrier.
• The Fix: Include “Fire caulking and sealing of all penetrations” in the Plumber’s scope.

The Fixture Specification Sheet

The most frequent source of plumbing change orders is “Specification Drift.” This happens when the budget says “Standard Fixtures” but the client picks out a wall-mounted faucet that requires a specialized rough-in valve and custom backing in the wall.

To prevent this, every plumbing bid should be linked to a Fixture Specification Sheet. This is a master list of every SKU (Stock Keeping Unit) for every sink, faucet, and shower head in the project.

Vague terms like “Standard White Toilet” are a recipe for disaster. Does that mean a $150 basic unit or a $600 comfort-height, one-piece model? By requiring the plumber to bid against a specific SKU list, you ensure that their “Trim-Out” labor is accurate for the complexity of the actual products being installed. If the client changes a spec later, you have a clear “Base Line” to calculate the change order.

Interface Points (Coordination)

• vs. HVAC: Who hooks up the gas to the furnace? Usually, the Plumber brings the gas pipe to the unit and installs a shut-off valve (dirt leg). The HVAC contractor makes the final flexible connection.
• vs. Electrician: Who wires the water heater? The Plumber sets the unit. The Electrician runs the power. The interface is the Disconnect Box.
• vs. Roofer: Who flashes the vent stacks? The Plumber pushes the pipe through the roof. The Roofer must install the boot/flashing.

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Detecting Plumbing Exclusions with Bid Bench

Plumbing proposals can be 20 pages of fine print.

Bid Bench acts as your second set of eyes:

1. Gas Line Check: Our AI scans to see if “Gas Piping” is included or excluded. (Some plumbers only do water/sewer).
2. Fixture Analysis: It highlights if the bid is “Labor Only” for fixtures or includes a “Fixture Allowance.”
3. Core Drilling: If this is a renovation job, Bid Bench flags if “Core Drilling” or “Cutting/Patching” is excluded, saving you a surprise bill later.

Stop the leaks in your budget.
[Start your 30-day free trial of Bid Bench today.]