CMA CMA Moisture & Building Science

Question 1

What is the primary driving force that allows moisture to move through building materials by capillary action?

Accepted Answer

Surface tension in pore spaces

Answer

Capillary action is driven by surface tension within small pores, pulling liquid water through materials without pressure.

Question 2

Which relative humidity (RH) range is generally considered the threshold above which mold growth is likely to begin on building materials?

Accepted Answer

Above 60% RH

Answer

Sustained relative humidity above 60% at material surfaces creates conditions favorable for mold colonization.

Question 3

In building science, what does the term 'dew point' refer to?

Accepted Answer

The temperature at which condensation forms on a surface

Answer

Dew point is the temperature to which air must be cooled for water vapor to condense into liquid at a given moisture content.

Question 4

Which type of vapor retarder is classified as Class I under the International Residential Code (IRC)?

Accepted Answer

Polyethylene sheeting (6 mil)

Answer

Class I vapor retarders have a permeance of 0.1 perm or less, which includes materials like polyethylene sheeting.

Question 5

What is the primary cause of interstitial condensation in wall assemblies?

Accepted Answer

Warm moist air meeting a cold surface within the wall cavity

Answer

Interstitial condensation occurs when warm, humid interior air migrates into a wall and contacts a surface below the dew point.

(CMA) Certified Mold Assessor Practice Test