What is a primary difference between continuous insulation and cavity insulation?

• A. Continuous insulation provides uninterrupted thermal resistance across the envelope.
• B. They are the same in performance.
• C. Continuous insulation increases interior surface roughness.
• D. Cavity insulation has no effect on R-value.

Answer: (A)

Continuous insulation provides uninterrupted thermal resistance across the building envelope, eliminating heat flow through framing members. This means the insulation runs continuously over studs and other framing, so there are no cold bridges that let heat bypass the insulation. That makes the overall R-value higher and the envelope more energy-efficient than a wall where insulation is only in the cavities.

Cavity insulation, by contrast, fills the spaces between studs but leaves the structural members as less insulated paths, so heat can still travel through those bridges. Because of that bridging, the same amount of insulation in cavities doesn’t achieve the same continuous resistance as a full, continuous layer. The idea that they perform the same or that cavity insulation has no effect on R-value isn’t accurate, and the notion that continuous insulation mostly changes interior surface roughness isn’t the defining difference.