IICRC WRT PROFESSIONAL
CERTIFICATION EXAM 2027
QUESTIONS AND ANSWERS
1. According to the ANSI/IICRC S500-2021, which factor is most critical when determining the
initial number of air movers for a water damage restoration project?
A. The square footage of affected floor, wall, and ceiling surfaces
B. The total volume of the affected space in cubic feet
C. The grain per pound (GPP) differential between the air and the material
D. The specific type of dehumidifier being used on-site
Answer: A
Conceptual Explanation: The S500 standard provides a formula for the initial air mover
calculation based on the square footage of affected surfaces, including floors, walls, and
ceilings.
2. When air temperature increases while the actual moisture content (GPP) remains constant,
what happens to the relative humidity (RH)?
A. Relative humidity increases
B. Relative humidity remains unchanged
,C. Relative humidity decreases
D. Relative humidity fluctuates based on atmospheric pressure
Answer: C
Conceptual Explanation: As air temperature increases, its capacity to hold moisture
increases. If the moisture content remains the same, the relative humidity (the ratio of
current moisture to capacity) decreases.
3. Which Category of water originates from a source that does not pose a substantial risk
from any type of exposure, but can transition over time?
A. Category 2
B. Category 1
C. Category 3
D. Category 4
Answer: B
Conceptual Explanation: Category 1 water originates from a sanitary source. However,
once it contacts other surfaces or sits for over 24-48 hours, it can degrade into higher
categories.
4. What is the primary difference between an LGR (Low Grain Refrigerant) dehumidifier and a
conventional refrigerant dehumidifier?
A. LGR units pre-cool the intake air to remove moisture at lower GPP levels
, B. LGR units use desiccant wheels to absorb moisture
C. LGR units only work in temperatures above 90 degrees Fahrenheit
D. LGR units are specifically designed for Category 3 water only
Answer: A
Conceptual Explanation: LGR dehumidifiers use a double cooling or enhanced cooling
system to pre-cool the air, allowing them to continue removing moisture at much lower
GPP levels than conventional units.
5. Vapor pressure is directly related to which of the following psychrometric measurements?
A. Relative Humidity
B. Dew Point
C. Grains Per Pound (Humidity Ratio)
D. Dry Bulb Temperature
Answer: C
Conceptual Explanation: Vapor pressure is the force exerted by water vapor molecules in
the air and is directly proportional to the humidity ratio or Grains Per Pound (GPP).
6. In a Class 4 water intrusion, which material requires the use of specialized drying
equipment such as heat or high-pressure drying systems?
A. Standard gypsum board
B. Hardwood flooring or concrete
CERTIFICATION EXAM 2027
QUESTIONS AND ANSWERS
1. According to the ANSI/IICRC S500-2021, which factor is most critical when determining the
initial number of air movers for a water damage restoration project?
A. The square footage of affected floor, wall, and ceiling surfaces
B. The total volume of the affected space in cubic feet
C. The grain per pound (GPP) differential between the air and the material
D. The specific type of dehumidifier being used on-site
Answer: A
Conceptual Explanation: The S500 standard provides a formula for the initial air mover
calculation based on the square footage of affected surfaces, including floors, walls, and
ceilings.
2. When air temperature increases while the actual moisture content (GPP) remains constant,
what happens to the relative humidity (RH)?
A. Relative humidity increases
B. Relative humidity remains unchanged
,C. Relative humidity decreases
D. Relative humidity fluctuates based on atmospheric pressure
Answer: C
Conceptual Explanation: As air temperature increases, its capacity to hold moisture
increases. If the moisture content remains the same, the relative humidity (the ratio of
current moisture to capacity) decreases.
3. Which Category of water originates from a source that does not pose a substantial risk
from any type of exposure, but can transition over time?
A. Category 2
B. Category 1
C. Category 3
D. Category 4
Answer: B
Conceptual Explanation: Category 1 water originates from a sanitary source. However,
once it contacts other surfaces or sits for over 24-48 hours, it can degrade into higher
categories.
4. What is the primary difference between an LGR (Low Grain Refrigerant) dehumidifier and a
conventional refrigerant dehumidifier?
A. LGR units pre-cool the intake air to remove moisture at lower GPP levels
, B. LGR units use desiccant wheels to absorb moisture
C. LGR units only work in temperatures above 90 degrees Fahrenheit
D. LGR units are specifically designed for Category 3 water only
Answer: A
Conceptual Explanation: LGR dehumidifiers use a double cooling or enhanced cooling
system to pre-cool the air, allowing them to continue removing moisture at much lower
GPP levels than conventional units.
5. Vapor pressure is directly related to which of the following psychrometric measurements?
A. Relative Humidity
B. Dew Point
C. Grains Per Pound (Humidity Ratio)
D. Dry Bulb Temperature
Answer: C
Conceptual Explanation: Vapor pressure is the force exerted by water vapor molecules in
the air and is directly proportional to the humidity ratio or Grains Per Pound (GPP).
6. In a Class 4 water intrusion, which material requires the use of specialized drying
equipment such as heat or high-pressure drying systems?
A. Standard gypsum board
B. Hardwood flooring or concrete
