How to Become a Plumber in Kentucky

The Licensing Path: Apprentice to Master

Kentucky licenses plumbers through a centralized state system administered by the Department of Housing, Buildings and Construction (DHBC). For the standard in-state path, plumbers advance through the same credential tiers regardless of which county they work in; active, valid out-of-state licensees may use the exam pathway described below.

The path runs: Registered Apprentice → Licensed Journeyman → Licensed Master Plumber → Plumbing Contractor (business entity). Each personal credential step requires specific experience and, except apprentice registration, an examination; the contractor step adds business registration and compliance requirements under KRS Chapter 318 and 815 KAR Chapter 20.

Step 1: Register as an Apprentice

There is no exam and no state fee for apprentice registration, but you must register with the DHBC before your field hours count toward licensing. Apprentices work under the direct physical supervision of a licensed journeyman, who in turn operates under a master plumber's general oversight.

Standard apprenticeship programs — whether through a joint apprenticeship training committee (JATC), a union local, or a non-union employer — typically span four to five years and accumulate up to 8,000 field hours. However, the state's legal minimum under 815 KAR 20:030 to sit for the journeyman exam is two consecutive years of registered apprenticeship.

One critical task during apprenticeship: document everything. If you change employers, immediately get a signed experience affidavit from your supervising master plumber and secure copies of your W-2 tax forms. The DHBC scrutinizes undocumented gaps, and losing track of your hours when switching jobs is the single most common reason applications get delayed or denied.

Step 2: Pass the Journeyman Exam

After meeting the experience requirement, submit Form PLB-3 (exam registration) to the DHBC Licensing Branch in Frankfort with a $50 non-refundable exam fee and a recent passport photo. Forms must arrive at least three weeks before the exam date.

Exams are administered quarterly — February, May, August, and November — at testing centers in larger Kentucky cities. The journeyman exam has two parts, each lasting 2.5 hours:

• Written portion: Size pipe on a prepared drawing showing stacks, wastes, vents, and fixtures. You can bring a tabbed copy of the Kentucky Plumbing Code.
• Practical portion: Demonstrate physical plumbing connections using materials you bring yourself. The DHBC mails the required materials list one week before the test.

You need 75% overall with at least 70% on each section. If you do not pass within one year of your first exam notice, your application voids entirely and you must resubmit everything — fees, forms, and experience verification.

Step 3: Activate the Journeyman License

After passing, submit Form PLB-2 (license application) with a $60 license fee, a background check, and proof of U.S. citizenship or work authorization. The journeyman license authorizes independent installation, repair, and maintenance of plumbing systems — but you still cannot pull permits, advertise independently, or contract directly with the public. All work must be performed under the employment and oversight of a licensed master plumber.

Step 4: Advance to Master Plumber

After holding an active journeyman license for at least two of the preceding five years under a master plumber's supervision, you can sit for the master exam. Register with Form PLB-3 again, this time paying a $150 exam fee.

The master exam is written only (no practical section), covers advanced code application, system design, and business law, and requires 80% overall with 75% per section — a higher bar than the journeyman test.

To activate the master license: submit Form PLB-1 with a $250 license fee and proof of at least $250,000 in general liability insurance naming the DHBC as certificate holder. If you employ anyone, workers' compensation and unemployment insurance are also required.

What Comes After the Master License

A master plumber license is an individual credential. To operate a plumbing business, you need to register a business entity with the Kentucky Secretary of State, file a Letter of Representation designating yourself (or another active master) as the qualifying agent, and secure a $10,000 surety license bond.

The Kentucky Plumber License Guide covers every form, fee, and deadline across all four credential tiers — plus the local permitting layers in Louisville and Lexington that catch new licensees off guard.

See more Kentucky guides →