IICRC WRITTEN TEST 2025/2026 |REAL EXAM
QUESTIONS, ANSWERS & RATIONALES GRADED A+
1. Which category of water contains only non-harmful, non-pathogenic
contaminants?
A. Category 1
B. Category 2
C. Category 3
D. Category 4
Answer: A.
Rationale: Category 1 is “clean water” from a sanitary source (e.g., supply
lines); Category 2 is gray water; Category 3 is black/unsanitary.
2. Which water “class” indicates fast evaporation with large surface area
and minimal intrusion into materials?
A. Class 1
B. Class 2
C. Class 3
D. Class 4
Answer: A.
Rationale: Class 1: minimal water, low porosity materials, fast evaporation.
Class 4 involves low-porosity materials requiring specialized drying.
3. What does the term “psychrometrics” refer to?
A. Measurement of concrete humidity
B. Study of properties of air-water vapor mixtures
C. Testing of microbial colonies
D. Electrical safety testing
Answer: B.
Rationale: Psychrometrics is the science of air/vapor properties (temp, RH,
dew point, vapor pressure).
4. Which instrument directly measures relative humidity (RH)?
A. Thermometer
B. Hygrometer
C. Moisture meter pin probe
D. Anemometer
, Answer: B.
Rationale: Hygrometers measure air humidity; moisture meters measure
material moisture content.
5. An air mover increases drying by:
A. Lowering air temperature only
B. Increasing air velocity and evaporation at wet surfaces
C. Raising RH near the surface
D. Pressurizing building envelope
Answer: B.
Rationale: Air movers enhance convective airflow across wet surfaces,
increasing evaporation.
6. Which dehumidifier type is best for cold environments (low ambient
temps)?
A. Refrigerant (conventional) dehumidifier
B. LGR (low-grain refrigerant) dehumidifier
C. Desiccant dehumidifier
D. Centrifugal dehumidifier
Answer: C.
Rationale: Desiccant units perform well at low temps and low grain loads;
refrigerant units lose efficiency when near freezing.
7. What is the correct order of drying goals?
A. Raise humidity, raise temperature, document
B. Lower moisture content of materials to preloss, manage environment,
document
C. Remove contents first, then dry structure
D. Demolish wet materials immediately
Answer: B.
Rationale: Goal: return materials to normal moisture content safely; control
environment and document progress.
8. Which safety device protects workers from inhaling airborne
particulates during mold remediation?
A. Hard hat
B. NIOSH-approved N95 or higher respirator (as required)
C. Safety glasses
D. Steel-toe boots
, Answer: B.
Rationale: Respirators filter particulates; N95 or higher (e.g., half-face
P100) are used per risk assessment.
9. When is containment (isolation) generally required during mold
remediation?
A. For surface dusting only
B. When work is likely to generate significant airborne spores or disturb
large contaminated areas
C. For minor carpet cleaning only
D. Never required
Answer: B.
Rationale: Containment limits cross-contamination when spores are likely
to spread during disturbance.
10. Which of the following best describes “saturation” regarding a
hygroscopic material?
A. When the material’s internal moisture equals equilibrium relative
humidity (ERH) of air
B. When the material is dry to the touch
C. When the material releases all moisture
D. When the material color changes only
Answer: A.
Rationale: Saturation occurs when material moisture is at equilibrium with
surrounding air humidity.
11. An infrared (IR) camera is most useful for:
A. Measuring microbial count
B. Locating temperature differentials that may indicate moisture behind
surfaces
C. Measuring RH
D. Sealing containment
Answer: B.
Rationale: IR reveals thermal anomalies; wet areas often show different
temperatures due to evaporative cooling.
12. HEPA filters remove particles of what minimum size with high
efficiency?
A. 10 microns
QUESTIONS, ANSWERS & RATIONALES GRADED A+
1. Which category of water contains only non-harmful, non-pathogenic
contaminants?
A. Category 1
B. Category 2
C. Category 3
D. Category 4
Answer: A.
Rationale: Category 1 is “clean water” from a sanitary source (e.g., supply
lines); Category 2 is gray water; Category 3 is black/unsanitary.
2. Which water “class” indicates fast evaporation with large surface area
and minimal intrusion into materials?
A. Class 1
B. Class 2
C. Class 3
D. Class 4
Answer: A.
Rationale: Class 1: minimal water, low porosity materials, fast evaporation.
Class 4 involves low-porosity materials requiring specialized drying.
3. What does the term “psychrometrics” refer to?
A. Measurement of concrete humidity
B. Study of properties of air-water vapor mixtures
C. Testing of microbial colonies
D. Electrical safety testing
Answer: B.
Rationale: Psychrometrics is the science of air/vapor properties (temp, RH,
dew point, vapor pressure).
4. Which instrument directly measures relative humidity (RH)?
A. Thermometer
B. Hygrometer
C. Moisture meter pin probe
D. Anemometer
, Answer: B.
Rationale: Hygrometers measure air humidity; moisture meters measure
material moisture content.
5. An air mover increases drying by:
A. Lowering air temperature only
B. Increasing air velocity and evaporation at wet surfaces
C. Raising RH near the surface
D. Pressurizing building envelope
Answer: B.
Rationale: Air movers enhance convective airflow across wet surfaces,
increasing evaporation.
6. Which dehumidifier type is best for cold environments (low ambient
temps)?
A. Refrigerant (conventional) dehumidifier
B. LGR (low-grain refrigerant) dehumidifier
C. Desiccant dehumidifier
D. Centrifugal dehumidifier
Answer: C.
Rationale: Desiccant units perform well at low temps and low grain loads;
refrigerant units lose efficiency when near freezing.
7. What is the correct order of drying goals?
A. Raise humidity, raise temperature, document
B. Lower moisture content of materials to preloss, manage environment,
document
C. Remove contents first, then dry structure
D. Demolish wet materials immediately
Answer: B.
Rationale: Goal: return materials to normal moisture content safely; control
environment and document progress.
8. Which safety device protects workers from inhaling airborne
particulates during mold remediation?
A. Hard hat
B. NIOSH-approved N95 or higher respirator (as required)
C. Safety glasses
D. Steel-toe boots
, Answer: B.
Rationale: Respirators filter particulates; N95 or higher (e.g., half-face
P100) are used per risk assessment.
9. When is containment (isolation) generally required during mold
remediation?
A. For surface dusting only
B. When work is likely to generate significant airborne spores or disturb
large contaminated areas
C. For minor carpet cleaning only
D. Never required
Answer: B.
Rationale: Containment limits cross-contamination when spores are likely
to spread during disturbance.
10. Which of the following best describes “saturation” regarding a
hygroscopic material?
A. When the material’s internal moisture equals equilibrium relative
humidity (ERH) of air
B. When the material is dry to the touch
C. When the material releases all moisture
D. When the material color changes only
Answer: A.
Rationale: Saturation occurs when material moisture is at equilibrium with
surrounding air humidity.
11. An infrared (IR) camera is most useful for:
A. Measuring microbial count
B. Locating temperature differentials that may indicate moisture behind
surfaces
C. Measuring RH
D. Sealing containment
Answer: B.
Rationale: IR reveals thermal anomalies; wet areas often show different
temperatures due to evaporative cooling.
12. HEPA filters remove particles of what minimum size with high
efficiency?
A. 10 microns
