What is the purpose of a continuous exterior insulation (CEI) layer?

• A. CEI reduces thermal bridging, increases overall R-value, and helps create a continuous thermal envelope on the exterior.
• B. CEI primarily improves interior acoustic performance.
• C. CEI seals the interior surfaces to prevent moisture.
• D. CEI is only for aesthetic purposes.

Answer: (A)

Continuous exterior insulation wraps insulation around the outside of the wall so there’s no gap where the framing breaks the insulation. This creates a continuous thermal barrier that covers the studs and other structural members, which are normally points of heat loss. By eliminating these thermal bridges, the wall’s overall R-value increases and heat moves more slowly between indoors and outdoors, leading to more stable interior temperatures and better energy efficiency. It also helps form a true exterior thermal envelope around the entire wall, including corners and openings, reducing drafts. The other options miss the main purpose: CEI isn’t primarily about interior acoustics, interior moisture sealing, or cosmetic considerations.