Mechanical is major classification 6 on a Louisiana commercial license, and it is broad: heating, ventilation, air conditioning, refrigeration, hydronic and steam systems, pressure vessels, plumbing, gas piping, process piping and mechanical equipment. The license is required at a much lower value than general construction, and its trade exam, Mechanical Work, is given at PSI and is open book. This guide covers the threshold, how plumbing and the HVAC subclassification fit, and what PSI's content outline says about the exam.
The Contractors Licensing Law defines a mechanical contractor by the work, not the building: air conditioning, refrigeration, heating and plumbing for residential, commercial and industrial applications, plus ventilation, mechanical controls, boilers and other pressure vessels, steam and hot-water systems, gas piping and fuel storage, chilled-water and condensing-water systems, and industrial process piping, whenever the project value is $10,000 or more (La. R.S. 37:2150.1(13)). That threshold is a fifth of the $50,000 that triggers a general commercial license, and it applies to residential jobs too. The Board's classification list marks Mechanical “Trade Exam”.
A major classification covers its subclassifications (LAC 46:XXIX §301). Under Mechanical the list places 6.1 Heat, Air Conditioning, Ventilation, Duct Work and Refrigeration, which has its own, narrower exam, and 3.4 Industrial Pipe Work and Insulation. If your work is only HVAC and refrigeration, compare the 6.1 HVAC license before you choose.
Louisiana handles plumbing differently. Plumbing, major classification 7, is marked “Credential” rather than “Trade Exam” on the Board's list, and the Mechanical entry says that a mechanical contractor who performs plumbing work with a value over $10,000 must hold a master plumber license from the State Plumbing Board of Louisiana. The statute exempts a plumbing contractor who holds that master plumber license from any trade examination requirement, and the Board's FAQ adds the reverse point: a master plumber doing plumbing work valued at $10,000 or more also needs a commercial plumbing license from the LSLBC. Even so, plumbing code makes up a large part of the Mechanical Work exam, as the outline below shows.
A statewide license matters more for mechanical contractors than for most trades. Under section 37:2156.1(H), mechanical, plumbing and electrical contractors licensed by the Board are excluded from local, municipal and parish examination procedures and may bid and perform work in any local jurisdiction once they pay the appropriate fees, and the employees of statewide-licensed mechanical contractors are excluded from local examination or certification as a condition of working for them. Local permits and inspections still apply. Solar thermal work is also mechanical: a Mechanical license is required to connect piping or equipment for any solar thermal system with a project value of $10,000 or more (section 37:2156.3).
PSI's Louisiana outline sets the format: 100 questions, 240 minutes, and a minimum passing score of 70 correct, which is 70 percent. The fee is $140, and a retake is another $140. The questions come from 23 content areas. The largest are Gas Systems (10), Isometric Analysis (8), Boilers and Hydronics (6) and Sheet Metal and Ducts (6). The plumbing areas together make up 35 of the 100 questions: Water Supply 5, Plumbing Fixtures and Equipment 5, Drain, Waste and Vent 5, Traps and Interceptors 4, Cleanouts 3, Developed Length 3, Joints and Connections 3, General Plumbing Regulations 3, Water Heaters 2 and Backflow 2. The rest: Piping, Valves and Controls 5, Load Calculations 5, Hangers and Supports 4, Fire Sprinklers 4, Safety 4, Refrigerants and Refrigeration 4, Heating and Cooling Principles 4, HVAC Equipment 4, and Testing, Adjusting and Balancing 1.
It is open book, and the reference list is long: the 2018 International Plumbing Code, International Mechanical Code and International Fuel Gas Code; NFPA 13 (2002) for sprinklers and NFPA 58 (2011) for LP gas; ACCA Manual N (fifth edition, 2008), Manual D (2016) and the ACCA Ductulator; SMACNA's HVAC Duct Construction Standards (2005); Modern Refrigeration and Air Conditioning (20th edition); the Pipefitters Handbook (third edition); and 29 CFR Part 1926, or PSI's printed selections of it. For code questions the exam uses only the edition listed, so bring the 2018 codes whatever your parish enforces; for the other books, later editions are acceptable.
PSI's March 2026 bulletin applies to every Louisiana trade exam: you bring your own references, which you may highlight, annotate and tab with permanent tabs beforehand but not write in during the exam; loose papers are removed, so printed material must be bound; and only a silent, non-programmable calculator without an alphabet keyboard is allowed, with no scientific calculators. Eligibility from PSI lasts one year, cancellations need two days' notice, and a failed exam cannot be retaken for 30 days (LAC 46:XXIX §111).
With 240 minutes for 100 questions you have about two and a half minutes each, enough to look things up but not to read a chapter. Tab the sizing tables in the IPC and IFGC, the duct and ventilation chapters of the IMC, and the fixture-unit and developed-length material, and practice reading isometric piping drawings, since that skill alone is worth 8 questions. Separately from any state license, federal rules require anyone who could open the refrigerant circuit of an appliance during maintenance, service, repair or disposal to hold EPA Section 608 technician certification (40 CFR 82.161); our free EPA 608 practice covers Core and Types I to III. LICENA's Louisiana Mechanical Work bank follows the 23 outline areas, with a written explanation on every answer.
Practice the Mechanical Work exam LICENA's Louisiana Mechanical Work bank follows PSI's 23 content areas, with a written explanation on every answer in English, Spanish and Russian. The sample is free, no sign-up.
Try the free practice test → Louisiana HVAC license (6.1)