IICRC WRT EXAM 2026/2027 ADVANCED
CERTIFICATION PREP QUESTIONS
AND ANSWERS
1. According to the ANSI/IICRC S500, which category of water originates from a source that
does not pose substantial harm to humans but may transition due to contact with building
contents?
A. Category 1
B. Category 2
C. Category 3
D. Special Situations
Answer: A
Conceptual Explanation: Category 1 water originates from a sanitary source. However,
once it contacts other surfaces or sits stagnant, it can transition to Category 2 or 3.
2. What is the primary difference between a Class 3 and a Class 4 water intrusion?
A. The amount of water surface area involved.
B. The permeance and porosity of the affected materials.
,C. The presence of pathogenic contaminants.
D. The temperature of the water during the intrusion.
Answer: B
Conceptual Explanation: Class 3 involves the fastest evaporation rate with highly porous
materials, whereas Class 4 involves ‘deep-seated’ moisture in low-porosity materials like
hardwood or concrete.
3. A technician records an indoor temperature of 80°F and a relative humidity (RH) of 60%.
What is the approximate Grains Per Pound (GPP)?
A. 92 GPP
B. 72 GPP
C. 110 GPP
D. 128 GPP
Answer: A
Conceptual Explanation: Using a psychrometric chart, 80°F at 60% RH intersects near the
92 GPP line.
4. Which process describes the movement of moisture from an area of high vapor pressure to
an area of low vapor pressure?
A. Vapor diffusion
B. Capillary action
, C. Condensation
D. Sublimation
Answer: A
Conceptual Explanation: Vapor diffusion is the movement of water vapor molecules
through porous materials driven by vapor pressure differentials.
5. When using an LGR dehumidifier, at what GPP level does its efficiency significantly
decrease compared to a desiccant dehumidifier?
A. Below 55 GPP
B. Below 34 GPP
C. Below 70 GPP
D. Below 45 GPP
Answer: B
Conceptual Explanation: Low Grain Refrigerants (LGR) are effective down to about 34
GPP, whereas desiccants can continue to pull moisture at much lower levels.
6. Which tool is most effective for finding ‘hidden’ moisture behind ceramic tile without
damaging the surface?
A. Penetrating moisture meter
B. Thermal imaging camera
C. Thermo-hygrometer
CERTIFICATION PREP QUESTIONS
AND ANSWERS
1. According to the ANSI/IICRC S500, which category of water originates from a source that
does not pose substantial harm to humans but may transition due to contact with building
contents?
A. Category 1
B. Category 2
C. Category 3
D. Special Situations
Answer: A
Conceptual Explanation: Category 1 water originates from a sanitary source. However,
once it contacts other surfaces or sits stagnant, it can transition to Category 2 or 3.
2. What is the primary difference between a Class 3 and a Class 4 water intrusion?
A. The amount of water surface area involved.
B. The permeance and porosity of the affected materials.
,C. The presence of pathogenic contaminants.
D. The temperature of the water during the intrusion.
Answer: B
Conceptual Explanation: Class 3 involves the fastest evaporation rate with highly porous
materials, whereas Class 4 involves ‘deep-seated’ moisture in low-porosity materials like
hardwood or concrete.
3. A technician records an indoor temperature of 80°F and a relative humidity (RH) of 60%.
What is the approximate Grains Per Pound (GPP)?
A. 92 GPP
B. 72 GPP
C. 110 GPP
D. 128 GPP
Answer: A
Conceptual Explanation: Using a psychrometric chart, 80°F at 60% RH intersects near the
92 GPP line.
4. Which process describes the movement of moisture from an area of high vapor pressure to
an area of low vapor pressure?
A. Vapor diffusion
B. Capillary action
, C. Condensation
D. Sublimation
Answer: A
Conceptual Explanation: Vapor diffusion is the movement of water vapor molecules
through porous materials driven by vapor pressure differentials.
5. When using an LGR dehumidifier, at what GPP level does its efficiency significantly
decrease compared to a desiccant dehumidifier?
A. Below 55 GPP
B. Below 34 GPP
C. Below 70 GPP
D. Below 45 GPP
Answer: B
Conceptual Explanation: Low Grain Refrigerants (LGR) are effective down to about 34
GPP, whereas desiccants can continue to pull moisture at much lower levels.
6. Which tool is most effective for finding ‘hidden’ moisture behind ceramic tile without
damaging the surface?
A. Penetrating moisture meter
B. Thermal imaging camera
C. Thermo-hygrometer
