Which of the following is not a function of exterior house wrap?

• A. Insulate the wall
• B. Help keep water out
• C. Allow water vapor passage
• D. Help keep air out

Answer: (A)

Exterior house wrap acts as a weather-resistive barrier: it blocks liquid water from entering the wall, allows water vapor to diffuse outward so the wall can dry, and helps reduce air leakage. It does not provide meaningful thermal insulation, since it doesn’t add R-value to the wall. Insulation comes from the cavity or continuous insulation installed behind or around the wrap. So the statement that the wall is insulated by the wrap is not a function of exterior house wrap.