Missouri Journeyman Plumber License

What a Journeyman License Lets You Do

A licensed journeyman plumber in Missouri can perform installations, repairs, and alterations on plumbing and drainage systems without direct supervision. What you cannot do: pull permits, contract directly with property owners, or operate as an independent business. You must work under the employment of a licensed plumbing contractor or master plumber.

The journeyman credential is the bridge between supervised apprentice work and the master license that unlocks contractor authority.

How Many Years It Takes

The short answer is two to five years as an apprentice, depending on where you apply:

• Kansas City: 2 years of verified plumbing experience under a licensed master
• Jefferson City: 4 years / 8,000 hours as a registered apprentice
• Springfield: 4 years under a master, or 6 years of practical trade experience
• St. Louis City: 5 years of apprentice experience
• St. Louis County: 5 years of apprentice experience (board counts 1,500 hours as one year)

These thresholds are non-negotiable at the local board level. Kansas City's two-year path is the fastest on-ramp in the state, while the St. Louis metro's five-year standard reflects that region's more conservative board culture.

Documenting Your Hours

Every jurisdiction requires written proof of your field time. The standard documentation package includes:

• Notarized employer affidavits listing dates, hours, and scope of work
• W-2 tax forms confirming employment with a licensed plumbing company
• Trade school completion certificates (where applicable)
• DOL apprenticeship completion records (if you went through a registered program)

St. Louis County's Board of Plumbing Examiners is particularly strict — they require formal registration as an apprentice before they start counting your hours. Hours worked before registration may not count, even if you were employed by a licensed master. Register first, then accumulate.

The Journeyman Exam

Your exam depends on jurisdiction:

The ICC G28 exam (Journeyman Plumber with Gas) covers the International Plumbing Code and International Fuel Gas Code. Acceptance depends on the local jurisdiction.

For St. Louis County, budget for rising exam costs — IAPMO testing fees are escalating through January 2027. The journeyman written exam (online) hits $175 by July 2026, and the in-person written reaches $250 by January 2027.

Applying for Your Trade Card

Once you pass, submit your score report to the local building division or plumbing board. Processing times depend on the issuing jurisdiction. Fees for the card itself range from $30 (St. Louis County, St. Louis City) to $117 (Jefferson City).

Some boards require a local background check or reference letters — Kansas City asks for two reference letters from licensed plumbers who can vouch for your competence. Get those commitments lined up before exam day.

Planning Ahead

The journeyman license is a milestone, not the finish line. To eventually pull permits and run your own business, you need the master plumber credential — which requires one to five more years as a licensed journeyman, depending on jurisdiction. Start documenting your journeyman hours from day one.

The Missouri Plumber License Guide includes a jurisdiction-by-jurisdiction timeline and an experience hour tracker formatted for local board submissions.

See more Missouri guides →