CMA CMA Moisture & Building Science 2 — Questions and Answers
Question 1: What does the term 'Equilibrium Moisture Content' (EMC) mean in the context of building materials?
- The moisture level at which a material neither gains nor loses moisture to the surrounding air (Correct answer)
- The maximum moisture a material can hold before structural failure
- The moisture content required for mold germination
- The moisture reading taken 24 hours after water intrusion
Correct answer: The moisture level at which a material neither gains nor loses moisture to the surrounding air
EMC is the point at which a hygroscopic material's moisture content is in balance with the relative humidity of the surrounding environment.
Question 2: Which psychrometric property represents the total heat content (sensible + latent) of moist air?
- Wet-bulb temperature
- Specific humidity
- Enthalpy (Correct answer)
- Vapor pressure
Correct answer: Enthalpy
Enthalpy (measured in BTU/lb or kJ/kg) represents the total heat energy in moist air including both sensible heat and latent heat of water vapor.
Question 3: In a hot-humid climate like Florida, where should the vapor retarder be placed in a wall assembly?
- On the interior (warm-in-winter) side
- On the exterior (warm-in-summer) side (Correct answer)
- In the middle of the insulation layer
- No vapor retarder is needed in hot-humid climates
Correct answer: On the exterior (warm-in-summer) side
In hot-humid climates, the dominant moisture drive is inward (from hot, humid exterior), so the retarder belongs on the exterior side.
Question 4: What is the term for water moving upward through concrete or masonry due to capillary action?
- Condensation wicking
- Rising damp (Correct answer)
- Lateral infiltration
- Efflorescence flow
Correct answer: Rising damp
Rising damp describes the upward migration of ground moisture through porous masonry or concrete via capillary action.
Question 5: Which window condition is a reliable indicator of high indoor relative humidity and potential mold risk?
- Frosting on exterior pane in winter
- Condensation on interior pane in winter (Correct answer)
- UV discoloration of window frames
- Air leakage around window seals
Correct answer: Condensation on interior pane in winter
Condensation forming on the interior surface of windows in winter indicates indoor relative humidity is high enough that the glass surface has reached dew point.
Question 6: What does a high WUFI (Wärme- und Feuchtetransport) simulation result indicating 'mold growth potential' primarily depend on?
- Structural load calculations
- Temperature and relative humidity at the material surface over time (Correct answer)
- Building orientation relative to prevailing winds
- HVAC equipment sizing
Correct answer: Temperature and relative humidity at the material surface over time
WUFI is hygrothermal simulation software that calculates mold risk based on the surface temperature and relative humidity history of building assemblies.
CMA CMA Moisture & Building Science 2
What does the term 'Equilibrium Moisture Content' (EMC) mean in the context of building materials?