- The exam is 50 multiple-choice questions in two hours, closed book, with a 70% passing score.
- Four reference areas drive preparation: AIHA Field Guide, ACGIH Bioaerosols, IICRC S500-2021 and IICRC S520.
- Initial cost is $100 exam plus $300 certification, $400 total; renewal is $300 every two years.
- Eligibility requires attestation of current employment in structural mold investigation; CSMI applicants skip project sheets.
Identity Check: Which CSMI This Sheet Covers
Several unrelated credentials share the letters CSMI, and exam-prep pages sometimes blur them together. This cheat sheet covers exactly one: the Council-certified Structural Mold Investigator, certified by the American Council for Accredited Certification (ACAC). If you want the plain-language background first, see What Is CSMI? or What Does CSMI Stand For?.
The CSMI body of knowledge addresses three broad ideas: structural mold sources, potential health effects, and methods of locating and identifying microbial contamination. Everything below is organized around that scope. Facts come from the ACAC CSMI Candidate Handbook and its exam study guide (current undated web edition, research checked October 5, 2026). Where a detail is not published, this sheet says so rather than guessing.
The Numbers at a Glance
This is the part to print and tape above your desk.
| Item | CSMI Fact |
|---|---|
| Certifying body | American Council for Accredited Certification (ACAC) |
| Question count | 50 multiple-choice questions |
| Time limit | Two hours (written exam duration only) |
| Format | Closed book; at least four answer choices per question |
| Passing score | 70% |
| Ordering | Question and answer order randomized |
| Results | Immediate electronic result plus emailed result |
| Testing provider | Kryterion, Inc. |
| Delivery | Authorized testing center, secure online video proctoring, or instructor-proctored vocational option by arrangement |
| Validity | Two years |
The Four Reference Areas
The four preparation headings below come straight from the handbook's reference-organized list. They are unweighted preparation categories, not official weighted exam domains, and no percentage weights have been published or verified. Do not trust any site that hands you a neat percentage split. For a deeper walkthrough, read CSMI Exam Domains 2026: Complete Guide to All 4 Content Areas.
Domain 1: AIHA, Field Guide
The AIHA Field Guide for the Determination of Biological Contaminants (second edition, 2005) is the field-investigation anchor. Think about how contamination is located and identified in real buildings.
- Locating and identifying microbial contamination in structures
- Sampling approaches and how results are interpreted in context
- Limits of what a given sample type can and cannot tell you
Domain 2: ACGIH, Bioaerosols: Assessment and Control
The accepted editions are the first (1999) or second (2024). This reference connects airborne biological agents to assessment strategy and control.
- Bioaerosol assessment logic and exposure context
- Potential health effects, treated as education rather than medical diagnosis
- Control principles for airborne biological contaminants
Domain 3: IICRC, S500-2021
ANSI/IICRC S500, fifth edition, is the water damage restoration standard. Mold investigation lives downstream of moisture, so this is where sources and causes get explained.
- Moisture and water-damage fundamentals that lead to structural mold
- Terminology: the public study guide points to glossary pages 99-118
- Study-guide reading locations include sections A, B and 1 through 8
Domain 4: IICRC, S520
The mold remediation standard. Accepted editions are S520-2015 with R520-2015 (third editions) or S520-2024 (fourth edition).
- Remediation concepts that an investigator must recognize and communicate
- Condition classifications and how investigation findings feed remediation planning
- Edition awareness: know which edition you studied
Eligibility and Application Facts
Do not repeat the claim that the CSMI has "no requirements." Here is what is actually published:
- Attestation of current employment in structural mold investigation.
- Application and identity verification.
- Successful examination.
- Certification-board approval.
No minimum experience duration and no compulsory preparatory course are specified. CSMI applicants are explicitly exempt from project sheets. But because current employment is required, this is not a prerequisite-free credential. The full breakdown is in CSMI Requirements 2026.
Exam-Day Mechanics
Closed book means retrieval, not lookup
With 50 questions in two hours, you have roughly two and a half minutes per question on average. That is generous for recall questions and tight only if you stall on scenario items. Because the exam is closed book and the source material is four dense references, the real skill is knowing which reference owns which kind of answer.
Know which reference answers which question type
- "How do you find or identify it?" leans toward the AIHA Field Guide.
- "What does airborne exposure or health context imply?" leans toward ACGIH Bioaerosols.
- "Where did the moisture come from and what is it called?" leans toward S500 terminology.
- "What happens in remediation and how is it framed?" leans toward S520.
This mapping is a study heuristic, not an official blueprint. Real questions can blend references, so read every answer choice (at least four are offered) before committing.
Proctoring options
Kryterion delivers the exam either at an authorized testing center or through secure online video proctoring. An instructor-proctored vocational option exists by arrangement. Whichever route you choose, results appear immediately on screen and arrive by email.
Money, Validity and Renewal
| Cost Item | Amount (USD) |
|---|---|
| Examination fee | $100 |
| Certification fee | $300 |
| Initial total | $400 |
| Retake | $100 |
| Renewal (every two years) | $300 |
For the full picture including prep materials, see CSMI Certification Cost 2026.
Renewal checklist
Certification lasts two years. Current renewal procedures require:
- An updated photo
- 40 recertification credits: 10 for continued field activity plus 30 professional-development hours
- Supporting records retained in case of audit
Certificants are also bound by the ACAC Code of Conduct. Start logging credits from day one of your two-year cycle rather than hunting for documentation in the final month.
What CSMI Is Not
This sheet keeps the vocational CSMI scope separate from two other ACAC credentials, CMI and CMC. Their content charts must never be mixed into CSMI prep, and a "pooled" practice test that blends them will mislead you.
| Point | CSMI | CMI / CMC |
|---|---|---|
| Category | Vocational designation | Separate credentials |
| CESB accreditation | Not CESB-accredited | CESB-accredited |
| Project sheets | CSMI applicants exempt | Different application requirements |
Also remember that completing a course, or passing an exam taken solely for state licensing, does not confer ACAC certification. Only the ACAC process, ending in certification-board approval, does. For how the credential relates to job titles and employers, see CSMI Jobs and the broader overview in CSMI Certification.
Reading the Reported Pass Result Carefully
ACAC's 2025 exam pass ratio report was attributed in a prior review to 29 passes from 32 exam administrations, which ACAC rounded to 91%. Treat that with care:
- It was not independently re-verified from the full document for this article, since the PDF could not be re-fetched.
- It reportedly includes retakes and state-licensing-only exams, so it is not a first-attempt rate.
- It is a cohort statistic, not a guarantee for any individual.
- It is not the same thing as the 70% passing threshold, which is the score you personally need on your attempt.
The sample is also small, so a single result moves the percentage substantially. For a fuller treatment, read CSMI Pass Rate 2026: What the Data Shows, and for a realistic difficulty read see How Hard Is the CSMI Exam?
Key Takeaway
Do not let a high cohort percentage convince you to under-prepare. The exam is closed book and spans four substantial references. Your target is 70% on your own attempt, and a retake costs $100.
A Domain-Ordered Last-Week Plan
This is the one study-method section in the article, and it is tied to the reference areas. The ordering logic: start with moisture terminology because it underpins everything else, then move to field identification, then airborne assessment, then remediation, and finish with mixed review.
IICRC S500-2021 vocabulary and moisture sources
- Re-read the glossary pages (99-118 in the study guide's references)
- Explain, aloud, how water damage leads to structural mold
AIHA Field Guide and ACGIH Bioaerosols
- Review locating and identifying contamination, and how results are interpreted
- Review airborne assessment logic and health-effects education
IICRC S520 and mixed scenarios
- Connect investigation findings to remediation framing
- Work original scenario questions that cross references
Timed run
- Simulate 50 questions in under two hours
- Review misses by reference, not by question number
For a longer-horizon plan, use CSMI Study Guide 2026: How to Pass on Your First Attempt. For timed practice that matches the 50-question format, try the CSMI practice tests, and remember that any practice bank is a rehearsal tool, not proof of what appears on the real exam.
A Note on Pay and Return on Investment
It is tempting to quote a salary figure on a cheat sheet, but none is published for this credential in the sources behind this article, so none is given here. What can be said honestly: mold inspection is an occupation with its own pay patterns, and no source here proves that holding the CSMI causes a pay premium. Evaluate the $400 initial cost against your employer's expectations, your local market and any state licensing rules. Further analysis is in CSMI Salary Guide 2026 and Is the CSMI Certification Worth It?
Frequently Asked Questions
The CSMI exam has 50 multiple-choice questions with a two-hour limit. It is closed book, and each question offers at least four answer choices. The two hours refer to the written exam only, not course or practical-assessment time.
The passing score is 70%. You receive an immediate electronic result at the end of the exam and an emailed copy as well. The reported cohort pass result is a separate statistic and not your personal threshold.
The initial cost is $100 for the examination plus $300 for certification, totaling $400. A retake costs $100, and renewal every two years costs $300. Confirm current amounts on the ACAC fees page before paying.
Yes, in the sense that the application requires attestation of current employment in structural mold investigation. No minimum experience duration or mandatory preparatory course is specified, and CSMI applicants are exempt from project sheets, but the credential is not prerequisite-free.
Certification is valid for two years. Renewal currently involves an updated photo and 40 recertification credits, made up of 10 for continued field activity and 30 professional-development hours, plus the $300 fee. Keep supporting records because they may be audited.
One last reminder: this sheet is a memory aid built on the published handbook, not a substitute for the references themselves. Confirm any date, fee or deadline with ACAC before acting, and use the CSMI Exam Prep practice test site to pressure-test what you remember.