- How the MS-RB Exam Domains Are Structured
- Domain 1: Site Work, Footings and Foundations
- Domain 2: Concrete and Concrete Reinforcement
- Domain 3: Masonry
- Domain 4: Carpentry
- Domain 5: Associated Trades and Drywall
- Domain 6: Roofing
- Domain 7: Estimating, Plan Reading and General Code Requirements
- Domain 8: OSHA Safety
- Domain 9: Licensing
- Open-Book Rules and Approved References
- Scheduling Study Time Around Domain Weight
- Frequently Asked Questions
- The MS-RB trade exam covers 9 domains across 80 scored questions in three hours.
- Estimating, Plan Reading and General Code Requirements is the largest domain at 18 questions.
- Carpentry (15 questions) and Site work, Footings and Foundations (13 questions) round out the top three.
- Passing requires 70%, or 56 correct answers, on a computer-delivered, open-book PSI exam.
How the MS-RB Exam Domains Are Structured
The Mississippi Residential Builder License Exam (MS-RB) is administered by PSI Services LLC on behalf of the Mississippi State Board of Contractors (MSBOC) under the Residential Building classification. Candidates who pursue this classification are approved for new construction, construction management, remodeling, and roofing work on one- and two-family residential projects not exceeding three stories. Actual license scope is governed separately by MSBOC, but the exam itself is organized into nine content domains that PSI weights according to real-world frequency and importance in residential construction.
Unlike a generic contractor's test, the MS-RB trade exam is built specifically around Mississippi's approved code edition and residential building practices. Every one of the 80 scored questions falls into one of the nine domains below, and PSI may also insert one to ten additional unscored experimental questions per its April 23, 2026 bulletin - these count against your three-hour time limit even though they aren't scored. If you haven't already reviewed how these domains fit into overall exam difficulty, the MS-RB difficulty guide breaks down how question style and time pressure interact with content weight.
Domain 1: Site Work, Footings and Foundations
Site Work, Footings and Foundations - 13 Questions
This domain tests your understanding of how a residential structure interacts with the ground beneath it, from initial excavation through the foundation system that supports the framing above.
- Soil bearing capacity, grading, and drainage requirements around foundations
- Footing sizing, depth, and placement relative to frost lines and load paths
- Foundation wall types, waterproofing, and backfill practices
- Pipe and excavation safety considerations, which tie directly into the approved pipe/excavation reference material
Because this domain draws on one of the eight approved reference categories dedicated specifically to pipe and excavation work, candidates should be comfortable locating tables and specifications quickly rather than memorizing every value outright - the exam is open-book, and speed of reference navigation matters as much as raw recall.
Domain 2: Concrete and Concrete Reinforcement
Concrete and Concrete Reinforcement
This domain covers concrete mix design basics, placement, curing, and the reinforcement details that keep slabs, footings, and foundation walls structurally sound.
- Rebar sizing, spacing, and placement conventions
- Slab-on-grade construction and control joint placement
- Curing time and weather-related concrete practices
- Cross-referencing the approved concrete reference during scenario-based questions
Concrete questions often present a scenario - a described project condition - and ask you to identify the correct construction response. Being fluent with the approved concrete reference category ahead of test day speeds up these lookups considerably.
Domain 3: Masonry
Masonry
Masonry questions focus on brick, block, and mortar practices common to residential foundations, veneers, and chimneys.
- Mortar types and joint tooling
- Masonry wall bracing and lateral support requirements
- Veneer ties and flashing at masonry-to-frame transitions
- Chimney and fireplace construction basics
Masonry is a smaller-weighted domain compared to Carpentry or Estimating, but it still draws from its own dedicated approved reference category, so don't skip building familiarity with that document before exam day.
Domain 4: Carpentry
Carpentry - 15 Questions
Carpentry is the second-largest domain on the MS-RB trade exam, reflecting how central framing knowledge is to residential building work.
- Floor, wall, and roof framing systems and load paths
- Header and beam sizing for typical residential spans
- Truss installation and the bracing requirements covered in the BCSI truss bracing reference
- Fastener schedules and connection details from the 2021 International Residential Code
Because Carpentry carries 15 of the 80 scored questions, it deserves a dedicated review block using both the IRC and BCSI truss bracing reference. Candidates preparing a study plan should treat this domain with the same seriousness as Estimating - see the MS-RB Study Guide for a walkthrough of how to sequence review across the highest-weighted domains.
Domain 5: Associated Trades and Drywall
Associated Trades and Drywall
This domain rounds out the building envelope and interior finish knowledge a residential builder needs to coordinate subcontractors and pass inspections.
- Drywall hanging, taping, and finishing standards
- Insulation placement and vapor barrier requirements
- Coordination points with electrical, plumbing, and HVAC trades on the residential builder's scope
Even though a residential builder doesn't typically perform electrical or plumbing work directly, the exam expects you to know how those trades interface with framing, insulation, and finish schedules on a jobsite.
Domain 6: Roofing
Roofing
Roofing is explicitly listed among the scopes covered by the Residential Building classification, and this domain tests the technical knowledge behind that scope.
- Roof covering materials and installation methods
- Flashing details at valleys, penetrations, and roof-to-wall transitions
- Ventilation requirements for attic spaces
- Referencing the approved roofing reference category for material-specific specs
Domain 7: Estimating, Plan Reading and General Code Requirements
Estimating, Plan Reading and General Code Requirements - 18 Questions
This is the single largest domain on the exam, and it functions almost as a cross-cutting category that touches every other domain.
- Reading residential plans, elevations, and details for material takeoffs
- Basic quantity and cost estimating for common residential components
- General code requirements pulled from the 2021 International Residential Code
- Interpreting specifications and identifying code-compliant construction methods across trades
Because this domain touches so many other content areas, strengthening your plan-reading and IRC navigation skills has a ripple effect across the rest of the exam. For a deeper dive into exactly how many correct answers you need and how the scoring works, see the MS-RB Passing Score guide.
Key Takeaway
Because Domain 7 is worth more than double most other domains, prioritize plan-reading practice and IRC code lookups early in your prep - proficiency here reinforces nearly every other content area.
Domain 8: OSHA Safety
OSHA Safety
This domain draws directly from the OSHA 29 CFR 1926 construction standard, one of the eight approved reference categories permitted during the exam.
- Fall protection requirements on residential jobsites
- Excavation and trenching safety
- Personal protective equipment standards
- General jobsite hazard communication practices
Bring a tabbed copy of 29 CFR 1926 if you plan to reference it, since pre-exam highlighting, underlining, and permanent tabs are allowed - but handwritten notes, loose papers, and temporary tabs are not.
Domain 9: Licensing
Licensing
The Licensing domain covers the regulatory framework surrounding the Residential Building classification itself, tying the trade exam back to MSBOC's application and compliance requirements.
- Classification scope and permitted project types
- Application requirements, including qualifying owner/officer or responsible managing employee criteria
- Insurance and workers' compensation obligations tied to licensure
- Renewal timelines and continuing education obligations for active qualifiers
Note that this trade exam's Licensing domain is separate from the standalone Law and Business Management examination, which MSBOC also requires. Reciprocity-based waivers of the trade exam do not waive that separate business-law requirement. For the full breakdown of who needs to apply and what documentation is required, see the MS-RB Requirements guide.
Open-Book Rules and Approved References
The MS-RB trade exam is computer-delivered and open-book, but "open-book" comes with strict limits. Only eight approved reference categories may be used:
- 2021 International Residential Code
- OSHA 29 CFR 1926
- Concrete references
- Masonry references
- Carpentry references
- BCSI truss bracing references
- Pipe/excavation references
- Roofing references
Using an older or newer edition than the one specified is done entirely at the candidate's risk - always confirm you're bringing the correct code edition. A silent, nonprinting, nonprogrammable calculator is allowed, and you may highlight, underline, and apply permanent tabs to your references before the exam. Handwritten notes, loose or attached papers, and temporary tabs are prohibited, so prepare your materials well before test day rather than scrambling at the testing center.
| Domain | Approx. Questions |
|---|---|
| Estimating, Plan Reading and General Code Requirements | 18 |
| Carpentry | 15 |
| Site work, Footings and Foundations | 13 |
| Concrete and Concrete Reinforcement | Remaining allocation |
| Masonry | Remaining allocation |
| Associated Trades and Drywall | Remaining allocation |
| Roofing | Remaining allocation |
| OSHA Safety | Remaining allocation |
| Licensing | Remaining allocation |
PSI's official bulletin confirms the 80-question total is scored, with the three heaviest domains identified above; the remaining six domains share the balance of the allocation. Passing requires 70%, equivalent to 56 correct answers, within the three-hour testing window.
Scheduling Study Time Around Domain Weight
Rather than studying all nine domains equally, allocate time proportional to question weight. This is one of the few places where a structured weekly approach genuinely pays off for MS-RB candidates specifically, because the domain sizes are so uneven.
Domain 7: Estimating, Plan Reading and General Code Requirements
- Practice plan takeoffs and quantity estimates
- Build fluency navigating the 2021 IRC quickly
Domain 4: Carpentry and Domain 1: Site Work, Footings and Foundations
- Review framing load paths and truss bracing requirements
- Study footing depth, soil bearing, and drainage rules
Domains 2, 3, 5, 6
- Concrete reinforcement, masonry, drywall/associated trades, and roofing details
- Cross-check each against its dedicated approved reference
Domain 8: OSHA Safety and Domain 9: Licensing
- Review 29 CFR 1926 fall protection and excavation rules
- Confirm application and renewal requirements
Eligibility to test lasts six months from approval, and retakes are unlimited as long as you pay the $120 fee each time - so there's no penalty for scheduling extra review time if your first attempt falls short. If eligibility expires, you'll need to reapply through MSBOC. For guidance on testing windows and how to schedule with PSI once approved, see MS-RB Exam Dates 2026.
If you're still deciding whether to pursue this path or want a broader primer before diving into domain-level study, start with What Is MS-RB? and then return to practice questions on our main practice test platform to test your domain-by-domain readiness. Running full-length, timed simulations on the practice site is one of the most reliable ways to gauge whether your 18-question weak spot in Domain 7 has actually closed before you pay for a real attempt.
Frequently Asked Questions
There are nine domains: Site work, Footings and Foundations; Concrete and Concrete Reinforcement; Masonry; Carpentry; Associated Trades and Drywall; Roofing; Estimating, Plan Reading and General Code Requirements; OSHA Safety; and Licensing.
Estimating, Plan Reading and General Code Requirements is the largest domain with 18 of the 80 scored questions, followed by Carpentry at 15 and Site work, Footings and Foundations at 13.
Yes, it's a computer-delivered, open-book exam limited to eight approved reference categories, including the 2021 International Residential Code and OSHA 29 CFR 1926. Non-approved or wrong-edition materials are used at the candidate's risk.
No. The nine domains cover only the residential builder trade exam. The Law and Business Management exam is a separate, required test with its own fee, and reciprocity waivers for the trade exam do not waive it.
You need 70% overall on the 80 scored questions, equivalent to 56 correct answers, within the three-hour time limit. There's no requirement to pass each domain individually.