BPI Moisture Management 2

Question 1

What is the primary function of a Class II vapor retarder?

Accepted Answer

Slow vapor diffusion without eliminating it

Answer

A Class II vapor retarder (permeance 0.1–1.0 perm) slows but does not stop vapor diffusion, allowing some drying potential.

Question 2

In a cold climate, where should the vapor retarder be located in a wall assembly?

Accepted Answer

On the warm-in-winter (interior) side of the insulation

Answer

In cold climates, the vapor retarder belongs on the interior (warm) side to prevent interior moisture from diffusing into the cold wall cavity.

Question 3

Which diagnostic tool is most appropriate for detecting moisture trapped inside wall cavities without invasive sampling?

Accepted Answer

Infrared thermography camera

Answer

Infrared thermography detects temperature differentials caused by evaporative cooling from wet materials, revealing hidden moisture.

Question 4

What does a dew point calculation help determine in building science?

Accepted Answer

The surface temperature at which condensation will occur

Answer

Dew point calculation identifies the temperature at which air becomes saturated and condensation begins on a surface.

Question 5

Which of the following building materials has the HIGHEST vapor permeance?

Accepted Answer

Unpainted gypsum board

Answer

Unpainted gypsum board is highly permeable (50+ perms), freely passing water vapor, unlike poly, kraft facing, or XPS.

(BPI) Building Performance Institute Certified Practice Test