- Understanding the Two-Part MA-MP Exam Structure
- Part I Written Domains (1-12)
- Part II Practical Domains (13-16)
- Why Domain Weighting Should Drive Your Study Plan
- Building a Domain-by-Domain Study Timeline
- Codes and References Behind Each Domain
- Registration, Retakes, and What Happens After Each Part
- Frequently Asked Questions
- The MA-MP exam has 16 domains split across two parts: 12 on the 80-question Written exam, 4 on the 40-question Practical exam.
- Gas Piping, Equipment, and Appliances is the largest Part I domain at 21 of 80 questions.
- Isometric Analysis dominates Part II with 20 of 40 questions - half the practical exam.
- Each part is scored independently and requires 70%; a passed part stays valid for one year while you retake only the failed one.
Understanding the Two-Part MA-MP Exam Structure
Before diving into the 16 individual content areas, it helps to understand how the Massachusetts Board of State Examiners of Plumbers and Gas Fitters, working through the Division of Occupational Licensure and PSI Services LLC, actually splits the MA-MP exam into two separately timed and separately scored sections.
Master Plumber Part I - Written covers 80 questions in 160 minutes and houses domains 1 through 12. Master Plumber Part II - Practical covers 40 questions in another 160 minutes and houses domains 13 through 16. Combined, the exam totals 120 questions across 320 minutes, but candidates should never treat that as one interchangeable pool of time - PSI's bulletin (dated October 3, 2025) makes clear the two parts run on independent clocks and independent 70% passing thresholds. A strong performance on Part I cannot offset a weak Part II, and vice versa.
If you're still mapping out how this structure fits into your overall prep timeline, our MA-MP Study Guide 2026 walks through pacing for both parts, and the MA-MP Passing Score guide breaks down exactly what a 70% on each part means in raw question counts.
Part I Written Domains (1-12)
Part I's 80 questions are distributed unevenly across 12 domains, and that imbalance is the single most important piece of strategic information a candidate can use when allocating study hours.
Domain 1: General Regulations, Inspections, and Permits - 9 items
Covers licensing structure, permitting workflow, and inspection authority under Massachusetts plumbing regulation.
- Know when permits are required versus exempt work
- Understand inspection sequencing and sign-off requirements
Domain 2: Gas Piping, Equipment, and Appliances - 21 items
The single largest domain in the entire exam, worth over a quarter of Part I. Expect deep coverage of gas appliance installation, sizing, and equipment clearances.
- Master gas pipe sizing methodology
- Know appliance connection and shutoff requirements cold
Domain 3: Venting - 12 items
The second-largest Part I domain. Covers venting configurations, sizing, and code-compliant termination.
- Distinguish venting requirements by fixture type and system design
Domain 4: Traps and Cleanouts - 2 items
Small in item count but tested precisely - trap seal requirements and cleanout placement rules.
Domain 5: Fixtures, Equipment, and Clearances - 2 items
Fixture spacing, access clearances, and equipment installation minimums.
Domain 6: Water Heaters - 3 items
Installation, venting interaction, and safety device requirements for water heating equipment.
Domain 7: Piping, Valves, and Controls - 3 items
Valve selection, control placement, and piping material compatibility.
Domain 8: Water Supply - 6 items
Supply sizing, backflow prevention, and water distribution system design basics.
Domain 9: Hangers and Supports - 2 items
Support spacing and material requirements across pipe types.
Domain 10: Drain, Waste, and Vent - 13 items
The third-largest Part I domain. DWV sizing, slope, and system layout are tested extensively.
- Practice sizing horizontal and vertical drainage runs
- Know minimum slope requirements by pipe diameter
Domain 11: Separators, Interceptors, and Grease Traps - 5 items
Sizing and placement rules for grease interceptors and oil/water separators.
Domain 12: Joints and Connections - 2 items
Approved joining methods across pipe materials and transition fittings.
Notice the pattern: Gas Piping, Equipment, and Appliances, Venting, and Drain, Waste, and Vent together account for 46 of the 80 Part I questions - well over half the written exam. If your prep time is limited, these three domains deserve first priority. For a broader look at how difficult candidates generally find this weighting, see How Hard Is the MA-MP Exam?.
Part II Practical Domains (13-16)
Part II shifts from regulatory recall to applied problem-solving. The 40 questions test isometric analysis and trade/gas calculations rather than pure code memorization, which changes the study approach entirely.
Domain 13: Isometric Analysis - 20 items
Exactly half of Part II. Candidates must read isometric drawings and apply code logic to piping runs, fixture connections, and system layout shown in diagram form.
- Practice reading isometric drawings under time pressure
- Cross-reference drawn systems against DWV and venting rules from Part I
Domain 14: General Trade Calculations - 5 items
Numeric problem-solving covering pipe sizing math, offsets, and fixture unit calculations.
Domain 15: Gas Piping - 7 items
Applied gas pipe sizing and layout calculations, distinct from the regulatory Gas Piping content tested in Part I.
Domain 16: Gas Venting - 8 items
Applied gas appliance venting calculations and configuration analysis.
Key Takeaway
Isometric Analysis alone is half of Part II. Candidates who can memorize code but struggle to interpret drawings under time pressure often lose points here - practicing with actual isometric problems matters more than re-reading code text for this section.
Why Domain Weighting Should Drive Your Study Plan
Treating all 16 domains as equally important is one of the most common planning mistakes. The table below lines up every domain against its part and item count so you can see exactly where the exam concentrates its questions.
| Domain | Part | Items |
|---|---|---|
| 1. General Regulations, Inspections, and Permits | I | 9 |
| 2. Gas Piping, Equipment, and Appliances | I | 21 |
| 3. Venting | I | 12 |
| 4. Traps and Cleanouts | I | 2 |
| 5. Fixtures, Equipment, and Clearances | I | 2 |
| 6. Water Heaters | I | 3 |
| 7. Piping, Valves, and Controls | I | 3 |
| 8. Water Supply | I | 6 |
| 9. Hangers and Supports | I | 2 |
| 10. Drain, Waste, and Vent | I | 13 |
| 11. Separators, Interceptors, and Grease Traps | I | 5 |
| 12. Joints and Connections | I | 2 |
| 13. Isometric Analysis | II | 20 |
| 14. General Trade Calculations | II | 5 |
| 15. Gas Piping | II | 7 |
| 16. Gas Venting | II | 8 |
Six domains - Gas Piping, Equipment, and Appliances; Venting; Drain, Waste, and Vent; Isometric Analysis; Gas Venting; and Gas Piping (Part II) - carry the bulk of the exam's scoring weight. The remaining ten domains combine for a much smaller share of total questions but still require a passing understanding, since Part I and Part II are each scored as a whole rather than domain-by-domain. For a deeper dive into how this weighting affects overall difficulty perception among candidates, check MA-MP Pass Rate 2026: What the Data Shows.
Building a Domain-by-Domain Study Timeline
Generic study techniques only help if they're mapped to the actual weight of each MA-MP domain. Below is one way to sequence preparation across several weeks, front-loading the heaviest domains first.
Gas Piping, Equipment, and Appliances + Venting
- Drill gas sizing tables and appliance clearance requirements
- Work through venting configuration scenarios repeatedly
Drain, Waste, and Vent + General Regulations
- Practice DWV sizing and slope problems
- Review permitting and inspection sequencing from Domain 1
Smaller Part I Domains (4-9, 11, 12)
- Batch-review traps, fixtures, water heaters, valves, water supply, hangers, separators, and joints
- These combine for meaningful points even though each is individually small
Isometric Analysis
- Practice reading and marking up isometric drawings against a clock
- Cross-check drawing interpretations against Part I venting and DWV rules
Gas Venting, Gas Piping (Part II), and General Trade Calculations
- Run applied sizing and venting calculations without reference material
- Simulate the closed-book, calculator-only conditions of test day
This sequencing isn't a universal formula - some candidates coming straight from apprenticeship-level Tier Five education may already be strong on regulatory domains and weaker on applied calculations, or the reverse. Use the domain weight table above to adjust your own order. Our MA-MP Cheat Sheet 2026 condenses the highest-yield facts from each domain into a single quick-reference page for final review.
Codes and References Behind Each Domain
Every domain traces back to a specific set of published references, and knowing which code governs which domain helps you study smarter rather than re-reading entire code books cover to cover.
- 248 CMR 10.00-10.23, the Massachusetts Uniform State Plumbing Code (2023 edition), underpins most Part I domains including venting, DWV, water supply, and fixtures.
- Specified 2021 and 2014 sections of 248 CMR apply to select regulatory and installation questions across several domains.
- NFPA 54 (National Fuel Gas Code, 2012) and NFPA 58 (Liquefied Petroleum Gas Code, 2011) govern the gas-related domains: Gas Piping, Equipment, and Appliances (Domain 2), Gas Piping (Domain 15), and Gas Venting (Domain 16).
- MGL Chapter 142 covers the statutory framework behind licensing and regulatory domains, feeding into Domain 1.
Because none of these references are permitted in the testing center, candidates preparing for domains tied to NFPA 54 and NFPA 58 in particular should work practice problems until the sizing logic is automatic, not something requiring a table lookup mid-exam.
Registration, Retakes, and What Happens After Each Part
Domain mastery only matters if you also understand the mechanics surrounding the exam itself. A few facts worth knowing before you schedule:
- The examination administration fee is $80 for an initial attempt or a retake, separate from the $31 application fee and $78 initial license fee.
- A minimum of 70% is required on each part independently - Part I and Part II do not average together.
- A passing part remains valid for one year, so if you pass Part I but fail Part II, you only need to retake Part II within that window.
- Master-level attempts are unlimited under the current bulletin.
- Eligible veterans receive a five-percent examination credit upon submission of DD214 documentation.
This retake structure is exactly why domain weighting matters so much: if you fail Part II because Isometric Analysis tripped you up, you don't need to re-study Gas Piping, Equipment, and Appliances from Part I - your focus narrows entirely to the failed part. For the full cost breakdown across application, examination, and licensing fees, see MA-MP Certification Cost 2026. For eligibility details including the journeyman license, work-hour, and Tier Five education requirements, see MA-MP Requirements 2026.
Once you're confident in your domain-by-domain readiness, running full-length timed simulations on our practice test platform is the best way to confirm you can hit 70% on both Part I and Part II under real exam conditions. Repeated practice through realistic MA-MP practice questions mapped to these exact 16 domains is far more useful than generic plumbing trivia, since question style and phrasing on PSI's computer-generated exam has its own rhythm you want to get used to before test day.
Frequently Asked Questions
There are 16 domains total: 12 in Part I - Written (80 questions) and 4 in Part II - Practical (40 questions), for 120 questions across both parts.
Gas Piping, Equipment, and Appliances is the largest domain in Part I at 21 of 80 questions. Isometric Analysis is the largest in Part II at 20 of 40 questions.
No. Scoring is by part, not by individual domain. You need a minimum of 70% on Part I as a whole and 70% on Part II as a whole.
No. A passing part remains valid for one year, so you only need to retake the part you failed, paying the $80 administration fee for that retake attempt.
No. Both parts are closed-book. Only a silent, non-printing, non-programmable calculator without alphabet keys is allowed, and PSI provides scratch paper at the test center.
Understanding exactly how these 16 domains are distributed across Part I and Part II is the foundation for every other piece of MA-MP preparation - from budgeting study hours to interpreting your eventual score report. For related groundwork before you get to domain-level studying, browse What Is MA-MP? and MA-MP Certification for the bigger licensing picture this exam sits within.
Ready to pass your MA-MP exam?
Put this into practice with free MA-MP questions across every exam domain.