How to Bid Commercial Plumbing Projects

Commercial plumbing drawings come in plan view (top-down floor layout), riser diagram (vertical stack and supply layout), and isometric (3D scope of complex fitting clusters). Start with the plan sheets to count fixtures (water closets, lavatories, urinals, drinking fountains, mop sinks, floor drains) and note the equipment schedule (water heaters, booster pumps, mixing valves). Move to the riser to count vertical pipe runs and tie-in points. Isometrics help on equipment rooms and water heater rooms. A clean takeoff lives or dies on reading these three sheet types together.

Pipe takeoff lists every section by material (copper, PEX, cast iron, PVC, no-hub), size (1/2 inch, 3/4 inch, 1 inch, etc.), length in linear feet, and fitting count (elbows, tees, couplings, valves). Wet walls and risers drive most of the count. Use a digital takeoff tool (PlanSwift, Bluebeam, On-Screen Takeoff) for accuracy, or hand-measure scaled drawings with a digital roller and tape. Commercial pipe pricing per linear foot: 1/2 inch copper Type L around $4.10 installed, 3/4 inch around $5.60, 1 inch around $7.20. Cast iron no-hub 4 inch runs around $32 per linear foot installed.

Equipment scope is its own bid section. Water heaters: commercial gas-fired tank heaters in the 75 to 119 gallon range run $4,800 to $9,200 in 2026; tankless rack systems run $18,000 to $45,000 depending on capacity. Booster pump packages start around $6,500. Backflow preventers run $1,400 to $4,200 by size and class. Mixing valves and circulating pumps add $400 to $1,800 each. Most equipment requires a startup and commissioning line on the bid. The mechanical drawings call out the equipment schedule; verify capacity ratings match the engineer's spec before pricing.

• Tank water heater 75 to 119 gal: $4,800 to $9,200 installed.
• Tankless rack system: $18,000 to $45,000 by capacity.
• Booster pump package: $6,500 to $14,000.
• Backflow preventer: $1,400 to $4,200 by size.

Public commercial projects (federal, state, local government) require prevailing wage under Davis-Bacon (federal) or state equivalents. Wage rates are published by labor classification (journeyman plumber, apprentice, foreman) and locality. Use the published rates, not your standard pay scale, for any project covered by prevailing wage. Bid bond (typically 5 to 10 percent of bid value), performance bond (typically 100 percent of contract value), and payment bond (also 100 percent) are common public-project requirements. Add bonding cost to the bid: roughly 1 to 3 percent of contract value for a well-rated contractor, higher for new firms.

Commercial markup typically runs 14 to 22 percent on direct cost, lower than residential. The lower number reflects larger job size, leaner overhead allocation per dollar of revenue, and more competition from established mid-size firms. A solo or small commercial shop may need 18 to 25 percent to cover overhead and target net profit, while a 30 plus employee firm running tight job costing can land at 12 to 16 percent. Show markup as a single line on the bid form, since the GC and the architect read consolidated margin, not buried per-fixture inflation.

Most commercial projects bill against AIA G702 or G703 forms tied to schedule of values. The plumbing subcontractor builds a schedule of values that maps each scope category (underground, wet walls, fixtures, equipment, startup) to a percent-complete billing milestone. The GC submits the consolidated G702 to the owner monthly; the sub gets paid on the schedule the GC publishes. Retainage typically runs 5 to 10 percent until substantial completion. Build your schedule of values to match the GC's billing cycle so your draws hit the same monthly window.