Estimating guide · plumbing
How to bid plumbing jobs
A plumbing bid has to account for every fixture and every foot of pipe — above and below the slab. This guide covers how plumbing contractors build an estimate from the plans.
1. Review the plumbing plans and fixture schedule
Read the plumbing plans, riser diagrams, fixture schedule, and Division 22 specs. Riser diagrams show what floor plans don't: stack sizes, vents, and how systems connect between floors.
2. Count fixtures and equipment
Count water closets, lavatories, sinks, urinals, showers, floor drains, hose bibbs, and drinking fountains by type. List equipment — water heaters, pumps, backflow preventers, interceptors — and get supplier quotes.
- Carriers and supports for wall-hung fixtures
- Trim, stops, and supplies
- Owner-furnished fixtures you only install
3. Take off underground and above-ground piping
Measure sanitary, storm, and vent piping by size and material, separating underground from above ground since labor and excavation differ. Then measure domestic hot, cold, and recirculating water.
Add fittings, hangers, insulation, cleanouts, and sleeves or firestopping at penetrations.
4. Price gas and specialty systems
Include natural gas piping, medical gas, or other specialty systems only if they're in your scope, and confirm the utility connection point.
5. Apply labor by phase
Break labor into underground, rough-in, and trim/finish. Apply your labor units by pipe size and fitting count, then adjust for multi-story work, access, and remodel conditions.
6. Add testing, permits, and markup
Carry pressure testing, disinfection, inspections, permits, and impact or tap fees where applicable. Then apply overhead and profit.
Frequently asked questions
Do plumbers bid per fixture?
Per-fixture pricing is common for quick budgets and residential work, but commercial bids should be built from piping takeoff plus fixtures.
What's the biggest risk in a plumbing bid?
Underground work — unknown soils, existing utilities, and tie-in depths can change cost quickly.
Should I separate rough-in and trim labor?
Yes. It improves accuracy and lets you bill and track progress by phase.
Buildbid.ai builds a custom AI agent that does these steps on your plans, at your rates, so every plumbing bid goes out faster.
See the plumbing estimating agent →