Moisture Control & Building Science Flashcards

What is the primary driver of mold growth in buildings?

Answer: Presence of moisture or water

Moisture is the single most critical factor for mold growth; without adequate water activity, mold cannot colonize or proliferate regardless of other conditions.

Which relative humidity (RH) level is generally considered the threshold above which mold growth risk increases significantly indoors?

Answer: 60%

Most guidance, including EPA recommendations, identifies sustained indoor RH above 60% as a condition that significantly promotes mold colonization on common building materials.

In building science, what is the 'dew point'?

Answer: The temperature at which air becomes saturated and moisture condenses

The dew point is the temperature at which a given parcel of air reaches 100% relative humidity and water vapor begins to condense into liquid on surfaces.

A vapor barrier installed on the wrong side of a wall assembly in a cold climate can:

Answer: Trap moisture within the wall cavity and promote mold

In cold climates, placing a vapor retarder on the cold (exterior) side traps interior moisture-laden air within the wall cavity, causing condensation and creating ideal conditions for mold growth.

Which of the following is a common intrusion pathway for liquid water into a building that a mold remediator should assess?

Answer: Roof flashing failures and foundation cracks

Roof flashing failures and foundation cracks are primary bulk water intrusion points that introduce liquid water directly into the building envelope, often leading to hidden mold growth.

What does 'equilibrium moisture content' (EMC) refer to in building materials?

Answer: The moisture level at which a material neither gains nor loses moisture to its surrounding environment

EMC is the moisture level at which a hygroscopic material is in balance with the relative humidity of its surrounding air, neither absorbing nor releasing moisture.

When using a pin-type moisture meter on drywall, what does a reading significantly above the baseline dry reading most likely indicate?

Answer: Presence of elevated moisture within the gypsum board or behind it

A pin-type moisture meter measures electrical resistance between probes; elevated readings in drywall indicate increased water content in the material or water migration from behind the surface.