How to Bid Commercial Plumbing Jobs: Takeoff, Labor Units and a Worked $18,170 Bid
Read the bid package, take off fixtures and pipe, turn counts into labor hours, price bonds, prevailing wage and retainage, and follow a worked office build-out bid.
To bid a commercial plumbing job, read the whole bid package, take off every fixture and foot of pipe from the plans, turn the counts into labor hours with your own labor units, then add materials, job costs and overhead, and price the total with a target margin. Write a proposal that says exactly what you included and excluded.
Bid price = (labor + materials + job costs + overhead) ÷ (1 − margin).
Hypothetical 3,000 sq ft office build-out with two restrooms and a break room: $15,983.32 of cost ÷ 0.88 = $18,162.86, rounded to an $18,170 bid at a 12% margin.
Commercial plumbing isn't a service call with a bigger invoice. You bid from drawings, the specs pick your pipe and fixtures, the GC lines your number up against three others, and the toilet carrier you missed on the takeoff is yours to buy.
Scope: US plumbing contractors bidding commercial work (tenant improvements, small retail, office and restaurant jobs) as a subcontractor or direct to an owner. Rates and labor units below are hypothetical assumptions. For residential and service work, see how to estimate a plumbing job.
1. Read the whole bid package before you count anything
Start with the documents, not the floor plan. The specs and the bid form decide what the GC expects inside your number.
- Plumbing drawings: floor plans, riser diagrams and the fixture schedule. Check the architectural sheets for wall types and ceiling heights.
- Specs: the plumbing section (Division 22 in the MasterFormat numbering many specs use) sets pipe material, fittings, insulation, approved fixture makers and testing.
- Fixture schedule: every fixture type, its make and model, and whether it's owner-furnished.
- Civil and site sheets: where your building sewer and water service connect, and who carries the work outside the building line.
- Addenda and bid form: changes since the plans went out, the due date, bond requirements, alternates and how long your price must hold.
Write your questions as you read and send them before the deadline. A request for information costs an email. Guessing costs a change order fight.
2. Take off fixtures, pipe and the items between them
A takeoff is a count of everything you'll install: each fixture type, each water heater and specialty item, and the linear feet of pipe by system, material and size.
- Fixtures: count from the fixture schedule and check each one against the floor plan. Note carriers for wall-hung fixtures and ADA models.
- Drain, waste and vent: measure from each fixture to the stack and out to the building drain, then add vent runs up through the roof.
- Water: cold, hot and recirculation lines from the service or tie-in point to each fixture.
- The small stuff: cleanouts, valves, hangers, insulation, trap primers, backflow devices and roof penetrations. These add up.
Mark every fixture and run as you count it so nothing gets counted twice. Keep the takeoff in the same lines you'll price.
3. Turn counts into hours with labor units
A labor unit is the hours one plumber needs for one item, like 3 hours to rough in and set a lavatory. Multiply each count by its unit and add them up.
Your best labor units are your own. Track real hours by task on a few jobs, split into underground, rough-in, trim and testing, and compare them with what you bid. Published manuals help, but they assume conditions your crew may not have.
Adjust for what the plans tell you: saw cutting a slab for underground, work in an occupied building, high ceilings, or a schedule that puts you on top of the framers and the electrician.
4. Price labor, materials and the job costs people forget
Labor gets a loaded hourly cost, materials get supplier quotes, and job costs get their own lines.
Labor. O*NET lists the national median wage for plumbers, pipefitters and steamfitters at $30.67 an hour (2025). This guide adds a 40% load for payroll taxes, workers' comp and benefits, so $42.94 an hour. Prevailing-wage jobs set the rate for you (section 6).
Materials. Get quotes on fixtures, water heaters and pipe, then add waste and small parts. Put an expiration date on the bid so a price jump between bid day and award isn't yours to eat.
Job costs. Permits and inspections, saw cutting and core drilling, testing, lift or scaffold rental, and close-out documents.
Overhead. Your office, trucks, insurance and estimating time. This guide charges $15 per labor hour. Work out your real number with the hourly rate calculator.
5. Worked example: a 3,000 sq ft office build-out
Hypothetical bid: a 3,000 sq ft office tenant improvement with two restrooms and a break room. Labor units, material costs and job costs are assumptions.
| Line item | Qty | Hours each | Labor hours | Material each | Material |
|---|---|---|---|---|---|
| Water closets, flush valve | 4 | 4.0 | 16.0 | $420 | $1,680 |
| Urinals | 2 | 3.5 | 7.0 | $380 | $760 |
| Lavatories | 4 | 3.0 | 12.0 | $260 | $1,040 |
| Break room sink | 1 | 4.0 | 4.0 | $350 | $350 |
| Mop sink | 1 | 4.0 | 4.0 | $450 | $450 |
| Electric water heater | 1 | 6.0 | 6.0 | $1,200 | $1,200 |
| PVC drain, waste and vent | 220 ft | 0.10 | 22.0 | $6.50 | $1,430 |
| Water piping | 300 ft | 0.08 | 24.0 | $4.00 | $1,200 |
| Testing and inspections | 1 | 8.0 | 8.0 | $0 | $0 |
| Totals | 103.0 | $8,110 |
Now price it:
| Cost line | Math | Amount |
|---|---|---|
| Labor | 103.0 hours × $42.94 | $4,422.82 |
| Materials | $8,110 + 5% waste and small parts ($405.50) | $8,515.50 |
| Job costs | $600 permit + $900 saw cutting and core drilling | $1,500.00 |
| Overhead | 103.0 hours × $15 | $1,545.00 |
| Total cost | $15,983.32 | |
| Price at 12% margin | $15,983.32 ÷ 0.88 | $18,162.86 |
| Bid | rounded up to the next $10 | $18,170 |
That leaves $2,186.68 of profit, a 12.0% margin, or about $6.06 per square foot. Miss one wall-hung carrier or 40 feet of vent and a good chunk of that profit is gone. That's why the takeoff and labor units carry the bid.
6. The commercial rules that change your number
Commercial and public bids come with terms that cost money. Read them before you price, not after you win.
Bonds. On federal construction, the bonds statute (formerly the Miller Act) requires performance and payment bonds on any construction contract over $150,000 (FAR 28.102-1). When a bid guarantee is required, it must be at least 20% of the bid price, capped at $3 million (FAR 28.101-2). Private owners and GCs can ask for bonds too. The premium is a job cost, so put it in before the margin.
Prevailing wage. Federal construction contracts over $2,000 that employ laborers and mechanics must state minimum wages based on prevailing rates set by the Secretary of Labor (40 U.S.C. § 3142). Many states have their own rules. If it applies, the wage determination replaces your labor rate.
Retainage. Many contracts hold back part of each payment until the job is done. That's cash you carry for months, so price it. See retainage.
Changes. Fixture swaps and moved walls are normal on build-outs. Know the change order process in the contract, and use construction change orders to get paid for every one.
7. Write a bid proposal the GC can compare
Your proposal is the price plus the rules it's built on. Keep it to one or two pages, and use the GC's bid form when there is one.
- Project, drawings and addenda you bid from, by sheet and date.
- Base bid as one number, with alternates and unit prices listed separately.
- Inclusions: what you're installing, in plain words.
- Exclusions: site utilities outside the building, tap and impact fees, fire sprinklers, gas piping, owner-furnished fixtures, patching and painting, excavation and backfill, overtime, bonds. Whatever you didn't price.
- Clarifications: assumptions you made where the plans were unclear.
- Validity and terms: how many days the price holds, payment terms and retainage.
Exclusions are where bids get compared unfairly. If another bidder carries the water heater and you show it as owner-furnished, say so in bold, or you'll look cheap on bid day and be expected to supply it later. A clear construction scope of work helps here.
Common commercial plumbing bidding questions
How do you bid a commercial plumbing job?
Read the full bid package, take off every fixture, specialty item and foot of pipe by system and size, multiply counts by your labor units to get hours, then add loaded labor, materials with waste, job costs and overhead. Divide the total by one minus your margin and submit a proposal with inclusions and exclusions.
What margin should I use on commercial plumbing bids?
There's no single right number. It depends on your overhead, the competition and the risk in the contract. The hypothetical example here uses 12% on top of a $15 per labor hour overhead charge. Price bonds, retainage and schedule risk as costs first, then pick the margin.
How is a commercial plumbing bid different from a residential one?
Commercial bids are built from drawings and specs instead of a walk-through, priced by takeoff and labor units, and compared line by line against other bidders. They often add bonds, prevailing wage, retainage, submittals and strict change order rules that residential jobs rarely have.
What should a plumbing bid proposal include?
The drawings and addenda you bid from, a base bid number, alternates and unit prices, a plain list of inclusions and exclusions, clarifications of any assumptions, how long the price is valid, and your payment terms. Use the GC's bid form when one is provided.
What to do on your next commercial bid
Track real hours on your next two jobs, split by underground, rough-in, trim and testing, so your labor units are yours. Then build the bid line by line with the formula above. The general method for any trade is in how to bid construction jobs, and the margin side is in plumbing business profit margin.
Already have a number? Upload the estimate to the estimate checker and see if it's priced too low. Starting a business in a different trade? See how to start a landscaping business.
