- ACI certification is awarded by ASHI after passing the NHIE and meeting field-experience requirements.
- The NHIE has 200 questions (175 scored, 25 pretest) with a 4-hour limit and closed-book format.
- Passing requires a scaled score of 500 on a 200-800 scale, not a raw percentage.
- ASHI's $449 certification application fee is separate from the $225 NHIE exam fee.
What ACI Certification Actually Is
ACI stands for ASHI Certified Inspector, a credential awarded by the American Society of Home Inspectors (ASHI) - one of the oldest and most respected professional associations in the home inspection industry. It is not a self-contained exam program; instead, ASHI ties ACI status to a candidate's performance on the National Home Inspector Examination (NHIE), a standardized test developed by the Examination Board of Professional Home Inspectors (EBPHI) and used broadly across state licensing programs.
Because so many people search "ACI" expecting a single certifying exam, it helps to be precise: passing the NHIE is a necessary step toward ACI, but it is not the same thing as ACI certification, and it does not by itself grant a state home inspector license. If you're still getting oriented, our overview pages on What Is ACI? and ACI Meaning walk through the terminology in more depth.
The Full Certification Requirements
To earn ACI status from ASHI, a candidate must satisfy several distinct requirements - not just pass a test. According to ASHI's published certification criteria:
- Pass the National Home Inspector Examination (NHIE)
- Complete at least 250 fee-paid home inspections that comply with ASHI's Standard of Practice
- Submit five compliant inspection reports for review and verification
- Agree to adhere to ASHI's Code of Ethics on an ongoing basis
These experience and reporting requirements belong specifically to ACI certification - they are not part of every candidate's eligibility to sit the NHIE itself. Someone new to the field may take the NHIE as part of a state licensing pathway long before they've logged 250 inspections. For a full breakdown of eligibility mechanics, timing, and documentation, see ACI Requirements 2026: Eligibility, Prerequisites & How to Qualify.
Key Takeaway
Passing the NHIE is the academic gate; the 250-inspection and five-report requirements are the professional-experience gate. Both must be cleared before ASHI confers ACI status.
The National Home Inspector Examination
The NHIE is a computer-based, closed-book exam delivered at proctored testing centers. PSI administers the exam in most states, while Pearson handles selected state programs. Regardless of vendor, the exam format is consistent nationwide:
- 200 total multiple-choice questions - 175 scored and 25 unscored pretest items mixed in without identification
- Four hours allotted to complete the exam
- Closed-book conditions - no personal notes, reference materials, or calculators permitted
- Scaled scoring on a 200-800 range, with 500 required to pass
Because pretest questions are unscored but indistinguishable from scored ones, candidates should treat every question on the screen as if it counts. For a deeper look at what the scaled score actually means and how it's calculated, read ACI Passing Score 2026: Exactly What You Need to Pass. And if you're weighing how difficult this exam really is relative to your background, How Hard Is the ACI Exam? Complete Difficulty Guide 2026 breaks down the format and content load in detail.
Exam Domains You Must Master
The NHIE content outline, effective April 1, 2024, organizes exam content into three domains. Knowing the weight of each domain should directly shape how you allocate study time.
Domain 1: Property and Building Inspection/Site Review (70%)
This is by far the largest domain and the one that determines most of your final score. It covers the physical systems and components inspectors evaluate on-site.
- Electrical systems, panels, and wiring conditions
- Structural components including foundations and framing
- Roofing materials, flashing, and drainage issues
- HVAC systems and their inspection points
- Plumbing supply, drainage, and fixture evaluation
- Life-safety concerns such as smoke and carbon monoxide detection
- Electric vehicle service equipment (EVSE) inspection basics
- Smart-home devices and their impact on inspection scope
Domain 2: Analysis of Findings and Reporting (20%)
This domain tests how well you interpret what you observe and translate it into a compliant, defensible report - a skill distinct from simply identifying defects.
- Prioritizing findings by safety and functional significance
- Writing clear, non-ambiguous report language
- Aligning report conclusions with the Standard of Practice
Domain 3: Professional Responsibilities (10%)
The smallest domain by weight, but still capable of costing points if ignored. It covers the ethical and procedural obligations inspectors carry.
- Code of Ethics obligations and conflict-of-interest scenarios
- Client communication expectations before and after inspection
- Scope-of-inspection boundaries and disclosure requirements
Because Domain 1 carries 70% of the exam, most of your preparation time should go there - but don't neglect Domains 2 and 3 simply because they're smaller; missing easy points on reporting and ethics questions is an avoidable mistake. A full walkthrough of each domain, with sample question styles, is available at ACI Exam Domains 2026: Complete Guide to All 3 Content Areas.
| Domain | Weight | Core Focus |
|---|---|---|
| Property and Building Inspection/Site Review | 70% | Systems: electrical, structural, roofing, HVAC, plumbing, life-safety, EVSE, smart-home |
| Analysis of Findings and Reporting | 20% | Interpreting observations, report writing, Standard of Practice alignment |
| Professional Responsibilities | 10% | Ethics, client communication, scope boundaries |
Fees and Costs Breakdown
ACI certification involves two separate fee categories that candidates frequently confuse:
- NHIE exam fee: $225 per attempt in most US states
- ASHI certification application fee: $449, paid separately from the exam fee
These figures don't include any prep materials, membership dues, or costs tied to accumulating your 250 fee-paid inspections. For a complete cost picture - including how retake fees and application timing interact - see ACI Certification Cost 2026: Complete Pricing Breakdown. If you're trying to decide whether the investment makes sense for your career goals, Is the ACI Certification Worth It? Complete ROI Analysis 2026 weighs the trade-offs directly.
Who Hires ACI-Certified Inspectors
ACI status signals to clients, real estate professionals, and employers that an inspector has cleared a standardized national exam and demonstrated a substantial track record of compliant, fee-paid inspections. Independent inspection firms, franchise inspection companies, and solo practitioners building a referral network all use ACI status as a credibility marker when pitching to real estate agents and homebuyers. Some multi-inspector firms specifically look for ACI credentials when hiring because it shortens the vetting process - the 250-inspection and five-report requirements have already done some of that work. For a broader look at where the credential opens doors, browse ACI Jobs, and for how ACI status can translate into compensation, see ACI Salary Guide 2026: Complete Earnings Analysis.
Building a Study Timeline Around the Domains
Generic study techniques only matter here insofar as they map onto the NHIE's domain weighting. Because Domain 1 covers 70% of the exam, it deserves the majority of your weeks - not an even three-way split.
Property and Building Inspection/Site Review
- Work through electrical, structural, and roofing content in depth
- Review HVAC and plumbing inspection points with practice questions
- Study EVSE and smart-home topics - newer additions to the outline
Analysis of Findings and Reporting
- Practice converting observed defects into report-ready language
- Drill scenario questions that test prioritization of findings
Professional Responsibilities
- Review Code of Ethics scenarios and scope-of-inspection boundaries
- Run a full 200-question timed simulation under closed-book conditions
This weighting-first approach avoids the common mistake of spending equal time on all three domains when Domain 1 alone determines the bulk of your scaled score. For a structured, week-by-week plan with more detail, see ACI Study Guide 2026: How to Pass on Your First Attempt, and pair it with realistic practice conditions using timed sets on our practice test platform before test day.
Key Takeaway
Spend roughly 70% of your study hours on property and building systems, since that domain determines 70% of your exam score.
Maintaining Your ACI Credential
Earning ACI status isn't the finish line. ASHI requires certified inspectors to complete 20 continuing education credits annually and to remain in adherence with professional standards, including the Code of Ethics. Skipping continuing education requirements can jeopardize active certification status, so many inspectors track CE credits alongside their inspection volume from the start rather than scrambling near a renewal deadline.
If you want a condensed reference for facts like these while you study - fee amounts, question counts, domain weights, and renewal requirements - bookmark ACI Cheat Sheet 2026: One-Page Review of Must-Know Facts.
Frequently Asked Questions
No separate ACI-only exam exists. ASHI ties ACI certification to passing the National Home Inspector Examination (NHIE), developed by EBPHI, plus additional experience and reporting requirements.
The NHIE contains 200 multiple-choice questions - 175 scored and 25 unscored pretest questions - with four hours allowed to complete the test.
You need a scaled score of 500 on a 200-800 scale. This is not a raw percentage of correct answers; see ACI Passing Score 2026 for more detail.
No. Passing the NHIE alone does not confer ACI certification or a state home inspector license. Licensing requirements vary by state and are separate from ASHI's certification process.
The NHIE fee is $225 per attempt in most states, and ASHI's certification application fee is $449, charged separately. See ACI Certification Cost 2026 for a full breakdown.