What results from compressing batt insulation?

• A. Compression changes color of insulation.
• B. Compression improves R-value.
• C. Compression lowers R-value and can cause gaps.
• D. Compression eliminates air leaks.

Answer: (C)

R-value measures how well insulation resists heat flow, and batt insulation is rated at its full, intended thickness. When you compress batt insulation, you squeeze the material thinner and reduce the trapped air pockets that help slow heat transfer. That means the effective R-value drops below the labeled value. In addition, compression can prevent the cavity from being filled evenly, creating gaps or tight spots around framing where heat can slip through. So compressing batt insulation lowers its R-value and can cause gaps. It doesn’t change color, it doesn’t improve insulation performance, and it doesn’t eliminate air leaks—the insulation itself isn’t a complete air barrier.