- Overview: The Three NHIE Content Areas Behind ACI Certification
- Domain 1: Property and Building Inspection/Site Review (70%)
- Domain 2: Analysis of Findings and Reporting (20%)
- Domain 3: Professional Responsibilities (10%)
- Exam Format, Fees, and Delivery Mechanics
- Mapping a Study Plan to the Domain Weights
- What Happens After You Pass the NHIE
- Frequently Asked Questions
- Property and Building Inspection/Site Review makes up 70% of the NHIE - study it first and longest.
- The NHIE has 200 questions (175 scored, 25 unscored) with a four-hour time limit.
- A scaled score of 500 on a 200-800 scale is required to pass - not a percentage.
- Passing the NHIE is one requirement; ACI also demands 250 fee-paid inspections and five reviewed reports.
Overview: The Three NHIE Content Areas Behind ACI Certification
The ASHI Certified Inspector (ACI) credential is awarded by the American Society of Home Inspectors, but the knowledge test candidates actually sit for is the National Home Inspector Examination (NHIE), developed by the Examination Board of Professional Home Inspectors (EBPHI). ASHI does not administer a separate proprietary exam for ACI - the NHIE is the examination component of the certification pathway, delivered on a content outline effective April 1, 2024. That outline is organized into three domains, and understanding how those domains are weighted is the single most useful piece of intelligence you can have before you start studying.
Unlike generic test-prep advice that treats every topic as equally important, the NHIE content outline is explicit: one domain - Property and Building Inspection/Site Review - accounts for 70% of the scored questions. The other two domains split the remaining 30% between report writing and analysis (20%) and professional conduct and standards (10%). If you've read a broad ACI Study Guide 2026: How to Pass on Your First Attempt already, this article goes deeper into exactly what each domain tests and how to prioritize your remaining prep time.
Domain 1: Property and Building Inspection/Site Review (70%)
This is by far the largest and most technically demanding domain on the exam, and it is where most candidates either build a comfortable margin above the passing score or fall short of it. The domain covers the physical inspection knowledge a home inspector applies on-site: identifying conditions, understanding system function, and recognizing defects across every major building component.
Property and Building Inspection/Site Review
Candidates must demonstrate working knowledge across the full range of residential systems and components an inspector encounters in the field.
- Electrical systems - service entrances, panels, wiring methods, grounding and bonding
- Structural components - foundations, framing, load paths, and common deficiencies
- Roofing - materials, drainage, flashing, and signs of failure or age-related wear
- HVAC systems - heating and cooling equipment, distribution, and ventilation
- Plumbing - supply, drain-waste-vent systems, water heaters, and fixtures
- Life-safety issues - smoke and carbon monoxide detection, egress, and related hazards
- Electric vehicle service equipment - increasingly common in newer content outlines
- Smart-home inspection issues - connected devices and systems inspectors now encounter regularly
Because this domain spans nearly every physical system in a house, candidates coming from a single trade background (say, electrical or HVAC) often underestimate how much breadth is required outside their specialty. The exam does not expect contractor-level depth in any one trade, but it does expect an inspector's-level familiarity across all of them - enough to recognize a defect, understand its implications, and know when a condition warrants further evaluation by a specialist.
The inclusion of electric vehicle service equipment and smart-home systems in the current outline reflects how quickly residential construction has evolved. These aren't legacy topics you can skip because they weren't emphasized in older prep materials. If your study resources predate the outline effective April 1, 2024, make sure you're supplementing with current content - this is one of the most frequent gaps candidates report when reviewing a ACI Cheat Sheet 2026: One-Page Review of Must-Know Facts built from outdated sources.
Key Takeaway
Because Domain 1 is worth 70% of the exam, even modest gains in electrical, structural, and roofing knowledge move your scaled score more than deep mastery of a narrow topic elsewhere.
Domain 2: Analysis of Findings and Reporting (20%)
The second domain shifts focus from "what did you observe" to "what do you do with what you observed." This is the analytical and communication layer of the profession - taking raw field observations and turning them into a defensible, client-usable report.
Analysis of Findings and Reporting
This domain tests an inspector's ability to interpret conditions correctly and communicate them clearly and appropriately.
- Distinguishing between cosmetic issues, maintenance items, and safety-significant defects
- Prioritizing findings by severity and urgency for the client
- Applying correct terminology and avoiding overstepping into areas outside the inspection scope
- Understanding how reporting choices connect to liability and client expectations
This domain matters even after you're certified: ACI candidates must submit five compliant reports for review and verification as part of the certification process, separate from the NHIE itself. That means the analytical skills tested in Domain 2 aren't just exam material - they're directly evaluated again when ASHI reviews your actual field reports. Strengthening this domain during exam prep pays off twice.
Domain 3: Professional Responsibilities (10%)
The smallest domain by weight, but not by consequence. Professional Responsibilities covers the ethical, legal, and procedural framework inspectors operate within - the rules that govern how an inspection is conducted and how an inspector interacts with clients, agents, and the property itself.
Professional Responsibilities
Expect questions on the standards and conduct expectations that frame every inspection, not just the technical findings.
- Adherence to a recognized standard of practice during inspections
- Code of ethics obligations, including conflicts of interest and client communication
- Scope-of-inspection boundaries and appropriate disclaimers
- General procedural and legal considerations relevant to the inspection process
Because ACI certification itself requires ongoing adherence to ASHI's Code of Ethics - not just a one-time exam answer - this domain is a preview of an obligation you carry for as long as you hold the credential. It also connects directly to ACI Requirements 2026: Eligibility, Prerequisites & How to Qualify, since ethical compliance is baked into the certification's ongoing standards, not just its entry exam.
Exam Format, Fees, and Delivery Mechanics
Knowing the content domains only helps if you also understand how the exam is actually delivered. The NHIE consists of 200 multiple-choice questions total: 175 are scored, and 25 are unscored pretest items used to evaluate future questions. You won't know which is which during the test, so every question deserves full attention. Candidates are given four hours to complete the exam.
Passing requires a scaled score of 500 on a 200-800 scale. This is not a raw percentage - a deeper explanation of how scaled scoring works is covered in ACI Passing Score 2026: Exactly What You Need to Pass, but the short version is that 500 represents a fixed competency bar rather than a fixed percentage of questions answered correctly.
| Exam Detail | Specification |
|---|---|
| Total Questions | 200 (175 scored, 25 unscored) |
| Time Allowed | 4 hours |
| Passing Score | 500 (scaled, 200-800 range) |
| Standard Exam Fee | USD $225 per attempt (most US states) |
| ASHI Certification Application Fee | USD $449 (separate from exam fee) |
| Delivery | Computer-based, proctored testing centers (PSI most states; Pearson selected state programs) |
| Materials Allowed | None - closed book, no notes, no calculators |
The exam is closed book. Personal notes, study materials, and calculators are all prohibited at the testing center, which means memorization and applied understanding matter more than reference lookups. For a full cost breakdown including how the exam fee and ASHI application fee interact, see ACI Certification Cost 2026: Complete Pricing Breakdown. If you're still working out when and where to sit for the exam, ACI Exam Dates 2026: Testing Windows, Deadlines & Scheduling walks through scheduling considerations across PSI and Pearson-administered states.
Mapping a Study Plan to the Domain Weights
A study schedule that ignores domain weighting wastes time. Since Domain 1 carries 70% of the exam, the majority of your study weeks should be allocated there, with Domains 2 and 3 layered in progressively as you approach test day rather than treated as separate, equal blocks.
Domain 1 Foundations
- Work through electrical, structural, and roofing systems in depth
- Add HVAC and plumbing once the structural basics are solid
- Review current material covering EV service equipment and smart-home systems
Domain 1 Reinforcement + Domain 2 Introduction
- Practice identifying defect severity and appropriate report language
- Continue drilling weaker Domain 1 subtopics identified from practice questions
Domain 3 and Integration
- Review code of ethics and standard-of-practice scope questions
- Take full-length timed practice sessions replicating the four-hour format
Final Review
- Focus remaining hours on lowest-scoring domain areas
- Simulate exam-day conditions: closed book, no calculator, timed
If you're unsure how this pacing compares to the overall difficulty of the exam, How Hard Is the ACI Exam? Complete Difficulty Guide 2026 discusses what makes the breadth of Domain 1 challenging for candidates from narrower trade backgrounds. And for a sense of how outcomes vary across candidates, ACI Pass Rate 2026: What the Data Shows puts the domain weighting in context with what the available data shows.
Throughout your prep, running full-length timed sets on our ACI practice test platform is one of the most direct ways to see which domain is actually costing you points - theory review only goes so far without exam-style repetition.
What Happens After You Pass the NHIE
It's worth being precise here: passing the NHIE alone does not confer ACI certification, and it does not grant a state home inspector license. The exam is one piece of a larger certification pathway. To actually earn the ACI credential, candidates must also complete at least 250 fee-paid home inspections that comply with ASHI's Standard of Practice and submit five compliant reports for review and verification, all while adhering to ASHI's Code of Ethics.
These field-based requirements are separate from exam eligibility - the 250-inspection and five-report thresholds apply to full ACI certification, not to every candidate simply sitting the NHIE. A detailed breakdown of how these pieces fit together, including timing and sequencing, is available in ACI Requirements 2026: Eligibility, Prerequisites & How to Qualify.
Once certified, maintaining ACI status requires 20 ASHI continuing education credits annually along with continued adherence to professional standards - a reminder that Domain 3's ethical content isn't a one-time hurdle but an ongoing obligation. If you're weighing whether the full pathway is worth the time and cost investment, Is the ACI Certification Worth It? Complete ROI Analysis 2026 and ACI Salary Guide 2026: Complete Earnings Analysis address that question directly, while ACI Jobs covers the kinds of employers and inspection firms that look for this credential.
For readers who arrived here still clarifying terminology, What Is ACI Certification? and ACI Certification lay out the full picture of what the credential represents beyond just the exam domains covered here.
Frequently Asked Questions
Start with Property and Building Inspection/Site Review since it represents 70% of the exam. Build a solid foundation there before layering in Analysis of Findings and Reporting and Professional Responsibilities.
Yes. Domain 1 explicitly includes electric vehicle service equipment and smart-home inspection issues as part of the current content outline effective April 1, 2024.
No. ASHI awards the ACI credential, but the examination component is the National Home Inspector Examination, developed by the Examination Board of Professional Home Inspectors and delivered through PSI or Pearson depending on the state.
Of the 200 total multiple-choice questions, 175 are scored and 25 are unscored pretest items, all within a four-hour testing window.
No. The NHIE produces a single scaled score of 500 on a 200-800 scale rather than separate pass/fail results per domain, so strong performance in one domain can offset a weaker showing in another.