What is on the Missouri Master Mechanical exam, and how do KC and St. Louis differ?
Missouri does not issue a single statewide mechanical contractor license. Each major metro runs its own program, and most of them lean on the ICC Master Mechanical (M-3) exam as the pass/fail gate.
Who licenses what in Missouri
- Kansas City, MO Trades Licensing uses the ICC Master Mechanical (M-3) for the Master tier
- Jackson County (outside KC city limits) reciprocates with KC for active Masters in good standing
- St. Louis City has its own Mechanical Contractor license and a separate written exam with a different code adoption year
- St. Louis County runs its own Tradesmen examination and accepts the ICC Mechanical with conditions
- Springfield uses ICC Mechanical and adds a business and law section
- Columbia uses ICC Mechanical with local amendments around hydronic snowmelt
What the Kansas City version actually tests
The KC Master Mechanical license is two written parts, taken separately, both open book, both administered at PSI.
Part one (General and Code): 80 questions, 70 percent to pass. Source material is IMC 2018 with KC amendments, IFGC 2018, IECC 2018, and Chapter 18 of the KC Code of Ordinances.
Part two (Specialty): 80 questions, 70 percent to pass. Topics: refrigeration, sheet metal, hydronics, gas piping sizing, ventilation, combustion air.
- PSI seat fee: $90 per part
- City license fee after passing: $200
- License validity: 2 years
- CEU requirement for renewal: 16 hours total, 8 of which must be code update hours
Study path that actually works
| Week | Focus | Hours |
|---|---|---|
| 1 | Tab the IMC, IFGC, IECC. Highlight KC amendments. | 8 |
| 2 | Combustion air, venting, gas pipe sizing tables | 10 |
| 3 | Refrigeration mechanical code, ASHRAE 15 references | 8 |
| 4 | Hydronics, expansion tank sizing, glycol percentages | 8 |
| 5 | Sheet metal duct sizing, equivalent length tables | 8 |
| 6 | Mock exams, timed, open book, full code in hand | 10 |
Where most candidates fail
1. Gas pipe sizing. Candidates memorize the standard CFH tables. The KC amendment adds an equivalent length factor that the NFPA chart does not assume. Apply the equivalent length before the table lookup, not after.
2. Combustion air on units over 400,000 BTU input. IFGC Section 304 gives you two methods, indoor and outdoor. KC accepts both but requires the calculation be shown on submitted plans. The amendment lives in Chapter 18, not the parent code.
3. Code section navigation under time pressure. Open book is only an advantage if your tabs are right. Bring paper code books, not a PDF on a laptop.
FAQ
Can I take the ICC Master Mechanical at home? ICC offers PRONTO remote proctoring for the M-3. KC accepts the PRONTO score certificate.
Does Missouri accept reciprocity? KC reciprocates with Lee''s Summit, Independence, and Olathe (KS). St. Louis City does not reciprocate with KC.
How long is the license good for? Two years in KC. 16 CEUs required to renew, of which 8 must be code update hours.
Disclosure: I built Master Mechanical Buddy, the app this guide is about. It includes Missouri amendments and a Socratic AI tutor that explains the gas pipe sizing tables in plain English.