What to Include in a Plumbing Bid Invite to Get Accurate, Comparable Numbers

A plumbing bid invite gets accurate, comparable numbers when it includes the current drawings and specs, a written scope split, the schedule, the jurisdiction, and a bid form every plumber fills out the same way. Leave any of those out and each bidder fills the gap with their own assumptions, which is why three plumbing numbers on the same job can be far apart.

Here is what St. Louis metro general contractors should put in the invite, and what to ask bidders to send back.

Why do plumbing bids on the same job come in so far apart?

Most spreads are not about price. They are about scope. One plumber carries underground to five feet outside the building, another carries it to the property line, and a third excludes it because the civil drawings were not in the package. One includes fixtures, one installs owner-furnished fixtures, one leaves out the water heater because it shows on the mechanical sheets. The numbers look different because the bidders priced different jobs.

A tight invite closes those gaps before the bids come in, so you spend bid day comparing prices instead of calling plumbers to find out what they left out.

What documents should go in the bid package?

• Full architectural, plumbing and civil sets, plus structural if there are below-slab conflicts or slab depressions
• Project manual with Division 22 specs and any owner standards
• Fixture and equipment schedules, including water heaters, pumps, interceptors and backflow assemblies
• Addenda issued to date, numbered, with a note on when the next one is expected
• Geotechnical report if underground or site utilities are in the plumbing scope
• Food service, medical or lab equipment drawings if those vendors' connections land on the plumber

If the design is not finished, say so plainly and tell bidders what to assume. A note like "price restroom cores per sheet P-201; break room is TBD, carry an allowance of X" gets you numbers you can actually line up.

How should you define the scope split?

Write down where plumbing starts and stops. Bidders should not have to guess. The splits that cause the most trouble on St. Louis metro jobs are these:

• Site utilities — where the plumber's sanitary, storm and water service end and the site contractor's begin (5 feet outside the building, the first manhole, the tap)
• Excavation and backfill — whether the plumber digs and backfills under the slab or the GC's site sub does it
• Fixtures — furnished and installed by the plumber, owner-furnished and plumber-installed, or by others
• Water heaters, booster pumps and backflow assemblies — plumbing or mechanical
• Gas piping — plumbing, mechanical or the gas utility
• Roof drains and overflow drains — who furnishes the drain bodies and who flashes them
• Core drilling, firestopping, access panels and concrete patching
• Temporary water and temporary restroom connections
• Permit fees, utility tap fees and impact fees — included, excluded, or by owner

A one-page scope matrix with a checkbox for each item is the fastest way to do this. Attach it to the invite and ask each bidder to return it with the number.

What schedule information do plumbers need to price the job?

Labor is usually the largest part of a commercial plumbing number, and schedule drives labor. Give bidders the target start, the date underground must be complete for the slab, any phasing, and any work that has to happen after hours or around an occupied building. A job that has to be roughed in on second shift or in three phases will cost more than one that runs straight through, and the bidder who knows that will price it correctly instead of sending a change order later.

Manpower matters here too. If the schedule is tight, ask how many people the bidder can put on the job at peak. Legacy Plumbing's workforce is UA Local 562 signatory, which lets us draw additional journeymen and apprentices when a schedule compresses.

Why does the jurisdiction belong in the bid invite?

The St. Louis metro is not one permitting market. The City of St. Louis, St. Louis County and its municipalities, St. Charles County and the cities inside it each run their own permit and inspection process, and some require the contractor to hold a license from that specific jurisdiction. Put the project address and the permitting authority in the invite so bidders can confirm they are licensed there and price inspection coordination and any local requirements correctly.

What should the bid form ask for?

A short, standard bid form is what makes bids comparable. Ask every bidder for the same items in the same order:

• Base bid lump sum
• Separate prices for underground, above-ground and site utilities if you may split the work
• Alternates, each priced as an add or deduct
• Unit prices for rock excavation, extra cleanouts, or other quantities you expect to change
• A written list of exclusions and qualifications
• Addenda acknowledged by number
• Lead times on fixtures, water heaters and any long-lead equipment

Ask bidders to keep exclusions in their own section instead of buried in a paragraph. That one request saves more time on bid day than anything else on this list.

How much time should plumbers get to bid?

Enough to do a real takeoff. A tenant suite with a few restrooms and a break room can be priced quickly. A ground-up building with underground, site utilities and a full fixture schedule takes longer, and a rushed number usually comes back with more exclusions. Post the bid date and the RFI cutoff in the invite, and answer RFIs by addendum so every bidder gets the same answer.

What to send Legacy Plumbing