Iowa’s Master Plumber with Gas examination is administered through Kirkwood Community College, the board-approved examination provider for the Iowa Plumbing and Mechanical Systems Board. It is an open-book examination of 125 questions in six hours, passed at 75 percent, tested on the 2024 Uniform Plumbing Code together with the Iowa State Plumbing Code 2024 Amendment Booklet. The PassProfessor Iowa Master Plumber with Gas program prepares candidates for that sitting and for the Iowa rules layered around it.
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What this credential certifies
The Iowa Master Plumber license, in the plumbing discipline, is the top individual plumbing license in Iowa’s system under Iowa Code chapter 105, the Iowa Plumber, Mechanical Professional, and Contractor Licensing Act. Licensing is overseen by the Iowa Plumbing and Mechanical Systems Board, within the Iowa Department of Inspections, Appeals, and Licensing. The board’s rules sit in Iowa Administrative Code agency 481, chapters 425 through 435 — chapter 425 for the State Plumbing Code, chapter 428 for licensure fees, chapter 429 for application, licensure, and examination, and chapter 432 for continuing education. Candidates who have seen older citations to agency 641 chapters should note that those chapter numbers are superseded; the operative rules are the agency 481 chapters.
The credential carries gas in its title for a reason. The examination title as printed by the provider is Master Plumber with Gas, and fuel gas piping is examined inside the plumbing code itself, as Chapter 12 of the 2024 Uniform Plumbing Code — part of the same code, the same sitting, and the same pass mark, not a separate gas add-on.
The examination at a glance
| Item | Verified position |
|---|---|
| Program | Iowa Master Plumber with Gas: the master examination in the plumbing discipline |
| Regulator | Iowa Plumbing and Mechanical Systems Board, within the Iowa Department of Inspections, Appeals, and Licensing, under Iowa Code chapter 105 and 481 IAC chapters 425–435 |
| Examination provider | Kirkwood Community College, the board-approved examination provider. There is no PSI bulletin for Iowa plumbing |
| Examination structure | Single written, proctored examination, delivered in person or online; open book |
| Size and time | 125 questions in 6 hours |
| Passing standard | 75 percent — a score of 75 percent or better is passing under 481 IAC 429.6(2)d |
| Tested references | 2024 Uniform Plumbing Code and the Iowa State Plumbing Code 2024 Amendment Booklet — the only two references allowed during the exam |
| Fees, kept distinct | $119 Kirkwood examination fee per attempt, payable to Kirkwood; plus a separate $35 board examination application fee per trade examination under 481 IAC 428.1(4) |
| Administrator note | PassProfessor is independent and is not affiliated with the Iowa Plumbing and Mechanical Systems Board, the Iowa Department of Inspections, Appeals, and Licensing, or Kirkwood Community College |
Tested code and adopted code are the same here — and that matters
In several states a candidate must keep two editions in mind at once: the code the state has adopted for field work and an older or different edition the exam still tests. Iowa is not one of those states for this examination. Tested equals adopted.
The adopted code is set at 481 IAC 425.1: Sections 101 and 102, Chapters 2 to 17, and Appendices A and M of the Uniform Plumbing Code, 2024 Edition, with Iowa amendments, effective March 26, 2025. The tested references are the same 2024 Uniform Plumbing Code plus the Iowa State Plumbing Code 2024 Amendment Booklet. Preparation that works from an earlier Uniform Plumbing Code edition, or from the unamended model code alone, is preparation for a different sitting.
Two Iowa specifics deserve emphasis. First, Iowa replaces the Uniform Plumbing Code trap-arm table with its own table in the adopted code, so trap-arm questions must be answered from the Iowa amendment, not from the model-code table a candidate may have memorised elsewhere. Second, the provider states the edition position precisely: although exam questions are based off information from a certain book edition, references brought to the exams can be from any edition — and the questions remain based on the 2024 edition. Bringing a different edition is permitted by that statement; answering from it where the 2024 text changed is the candidate’s own risk.
Fuel gas follows the same discipline. Fuel gas piping must comply with Chapter 12 of the 2024 Uniform Plumbing Code unless Iowa Code chapter 661, chapter 226 conflicts, in which case chapter 226 governs. No standalone NFPA 54 volume, mathematics book, or OSHA volume is listed for the Iowa plumbing examinations. Candidates who see such a book on a list for Iowa mechanical, HVAC, hydronics, or sheet metal examinations should not import it into the plumbing room: its absence from the plumbing list is deliberate.
What the master examination covers
Kirkwood publishes the master outline as percentages, not as fixed question counts, and this page follows that form exactly. The percentages sum to 100 percent of the 125 questions:
- Chapter 3, General Regulations — 5 percent. The code’s general rules for how plumbing work is governed and installed.
- Chapter 4, Fixtures and Fittings — 8 percent. Fixture requirements and the fittings that serve them.
- Chapter 5, Water Heaters — 5 percent. Water heater installation and protection.
- Chapter 6, Water Supply and Distribution — 11 percent. Supply systems, distribution, and sizing reasoning.
- Chapter 7, Sanitary Drainage — 18 percent. One of the two heaviest areas of the paper: drainage systems in depth.
- Chapter 8, Indirect Wastes — 5 percent. Indirect waste arrangements and air-gap protection.
- Chapter 9, Vents — 18 percent. The other heaviest area, equal in weight to sanitary drainage: venting systems in depth.
- Chapter 10, Traps and Interceptors — 5 percent. Traps — including Iowa’s own trap-arm table — and interceptors.
- Chapter 11, Storm Drainage — 10 percent. Storm and roof drainage systems.
- Chapter 12, Fuel Gas Piping — 7 percent. The gas content that gives this examination its full title.
- Isometric — 8 percent. Isometric reading and analysis as a written content area.
The shape of the outline is the study plan in miniature. Drainage and vents together account for more than a third of the paper. A candidate who is strong on fixtures and water heaters but thin on venting has the preparation exactly backwards for Iowa. Note also what distinguishes the master paper from the journeyperson paper beneath it: the journeyperson outline has no Isometric cell. The isometric work is a master-level expectation, examined here as written questions, not as a separate drawing examination.
There is no hands-on practical in this examination. The examination in rule is written and proctored, and no source describes a practical component or a separate drawing sitting for Iowa. Preparation should not promise one, and candidates should not expect one.
The room, the books, and the clock
The examination is open book, and the book rules are specific. Only the two listed references may be used. Bound or loose-leaf copies are allowed; photocopies are not. Highlighting and permanent tabbing done before arrival are allowed; Post-it notes are not. No handwritten notes may be in the books, references may not be shared, and they are checked before and after the sitting. Six hours rewards a candidate whose books are organised for retrieval — tabbed, familiar, and in the 2024 edition the questions are keyed to.
The sitting is offered periodically at rotating Iowa sites, with sixteen test cities listed by the provider, and the examination may be conducted in person or online. The score is shown on screen at the end as a percent correct. Results are confidential to the applicant and the Board, the exam is not subject to review, and the vendor will identify failed sections on request — a failed candidate therefore leaves knowing which outline areas to rebuild.
Who may sit, and the order the steps run in
Board approval comes before Kirkwood registration; that order is mandatory. A master candidate qualifies by one of two routes: previously licensed as a journeyperson in the discipline with at least two years of journeyperson work experience in the discipline, or previously licensed as master in the applicable discipline in another state or local jurisdiction. Every license applicant must be at least 18 years old.
The application for examination must be submitted at least 15 business days before taking an examination. Approval is valid for one year, during which the candidate may test as many times as necessary, paying the Kirkwood fee for each attempt; after that year, the candidate reapplies with a new application and a new $35 board fee. Passing is not the last step: a passing score expires if licensure is not applied for within two years of passing notification, and a license is not automatically issued on passing.
The two fees must never be merged. The $119 is Kirkwood’s examination fee — non-refundable, non-transferable, payable to Kirkwood for each attempt. The $35 is the Board’s examination application fee per trade examination, set in rule at 481 IAC 428.1(4) and stated on the Department’s examination page. Figures of five hours or $109 for this examination circulate in secondary material; both are superseded. Six hours and $119 govern.
After passing: the license, its term, and its renewal
The master license runs on a three-year term. The master license fee in rule is $240 for the initial license and $240 for renewal, with initial licenses for less than three years prorated by a one-sixth deduction per six-month period. All Iowa licenses in this system expire June 30 every three years, and renewal — without examination — is due at least 30 days before expiration. The late-renewal ladder in rule is short and worth knowing before it is needed: on or before July 31 there is no late fee; from August 1 through August 31 the late fee is $60 plus the renewal fee; after August 31 through the following June 30 it is $100 plus the renewal fee. All fees in this system are nonrefundable.
Continuing education applies to each active or inactive master licensee across the license term. For a single license the total is eight hours per three-year term, in three named parts: two hours of Safety covering Iowa OSHA Act content, two hours of Code covering the Iowa plumbing code, and four hours of Discipline content. A licensee holding multiple licenses completes four hours of Safety and eight hours of Discipline, with the Code hours unchanged. Up to one-half of the continuing education may be computer-based or online.
If the first sitting does not pass
Iowa’s retake position is plain. A candidate who does not pass must register and pay for a new exam with Kirkwood. No waiting period between attempts is stated in the primary sources, and no numeric retake cap exists in the statute or the rule — the statute provides that failing applicants shall be allowed to retake the examination at a future scheduled time. The practical limits are the ones already described: the one-year approval validity, the per-attempt Kirkwood fee, and the two-year life of a passing score once one is earned.
What the PassProfessor program will cover
The 2024 code, as Iowa amended it. Our catalog now includes preparation built specifically for the Iowa Master Plumber with Gas sitting: the 2024 Uniform Plumbing Code chapters in the weights Kirkwood publishes, with sanitary drainage and vents given the depth their combined share of the paper demands, the Iowa State Plumbing Code 2024 Amendment Booklet treated as a tested reference in its own right, Iowa’s own trap-arm table taught in place of the model-code table, fuel gas piping taught as Chapter 12 work, and the isometric content that appears on the master outline and not on the journeyperson outline.
Open-book performance, not just code knowledge. Because this is an open-book, six-hour sitting with strict rules about what may be in the books, the program trains retrieval: knowing which chapter answers which kind of question, and reaching it quickly in a properly tabbed 2024 edition and Amendment Booklet.
Independence, stated plainly. PassProfessor is an independent preparation provider, not affiliated with the Iowa Plumbing and Mechanical Systems Board, the Iowa Department of Inspections, Appeals, and Licensing, or Kirkwood Community College. Completing this program confers no license and no examination approval; the Board approves candidates, Kirkwood administers the examination, and the Board licenses.
Tell me when enrollment opens. The Iowa Master Plumber with Gas program is in the works and enrollment is not yet open. Leave an email address and PassProfessor will write to you when the program is ready — and only about this program. Our companion guide, the Iowa Master Plumber with Gas Exam Guide, works through the credential, the outline, and the licensing route in full.
Frequently asked questions
Who administers the Iowa Master Plumber with Gas examination?
Kirkwood Community College, as the Board’s approved examination provider. Board approval is required before a candidate registers with Kirkwood. There is no PSI bulletin for Iowa plumbing.
How many questions are on the master examination, and how long does it run?
125 questions in 6 hours, open book. A score of 75 percent or above is required to pass.
What does the examination cost?
Two separate fees: a $119 examination fee payable to Kirkwood for each attempt, and a $35 board examination application fee per trade examination. They are charged by different parties for different steps.
Which code edition is tested?
The 2024 Uniform Plumbing Code together with the Iowa State Plumbing Code 2024 Amendment Booklet. Tested equals adopted in Iowa: the same 2024 edition, with Iowa amendments effective March 26, 2025, is the adopted State Plumbing Code.
Is there a practical or drawing examination?
No hands-on practical is described for this examination, which is written and proctored. Isometric content appears as a written area worth 8 percent of the master outline; it is not a separate drawing sitting.
Who is eligible for the master examination?
A candidate previously licensed as a journeyperson in the discipline with at least two years of journeyperson work experience in the discipline, or previously licensed as master in the discipline in another state or local jurisdiction. Applicants must be at least 18.
How long is the master license term, and what renewal education applies?
Three years, with all licenses expiring June 30 every three years. A single-license master completes eight hours of continuing education per term: two hours Safety, two hours Code, and four hours Discipline.
What happens if I fail?
You register and pay for a new exam with Kirkwood. No waiting period or numeric attempt cap is stated in the primary sources; your examination approval remains valid for one year.
Is PassProfessor affiliated with the Board or with Kirkwood?
No. PassProfessor is an independent preparation provider. The Board approves and licenses; Kirkwood administers the examination.
When does enrollment open?
The program is in the works and enrollment is not yet open. Leave an email address on this page and PassProfessor will write to you when the program is ready — and only about this program. For the full route and outline, see the Iowa Master Plumber with Gas Exam Guide.