CMA Moisture & Building Science Flashcards

Which ASHRAE standard provides guidance on ventilation rates to maintain acceptable indoor air quality and control moisture?

Answer: ASHRAE 62.1

ASHRAE 62.1 (Ventilation for Acceptable Indoor Air Quality) specifies minimum ventilation rates for commercial buildings to control contaminants including moisture.

What is the primary function of a rain screen wall system in relation to moisture control?

Answer: To create a drainage and drying space between cladding and the weather-resistant barrier

A rain screen system creates an air gap behind the cladding that allows water to drain down and air to circulate, promoting drying and preventing moisture accumulation.

What moisture measurement unit is commonly used to express the permeance of vapor retarders?

Answer: Perm

Permeance is measured in perms (grains of water vapor per hour, per square foot, per inch of mercury pressure difference).

In building diagnostics, what does a blower door test primarily measure?

Answer: Overall air leakage rate of the building envelope

A blower door test depressurizes or pressurizes a building to measure total air infiltration/exfiltration, which affects moisture transport and indoor air quality.

Which type of crawl space design is recommended by building science experts to minimize moisture and mold problems?

Answer: Conditioned (sealed) crawl space with vapor barrier on the ground

Research shows that sealed, conditioned crawl spaces with a ground vapor barrier consistently perform better for moisture control than vented crawl spaces.

What is the significance of 'thermal bridging' to mold risk in building assemblies?

Answer: It increases condensation risk at cold spots on interior surfaces

Thermal bridges create locally cold spots on interior surfaces where warm, moist indoor air can reach dew point and condense, creating conditions favorable for mold.