Describe how to avoid compression of batt insulation during installation and why it matters.

• A. Compress the batts slightly to fit more insulation.
• B. Do not compress batts; install without forcing into cavities; use proper supports or netting; compression lowers R-value and can cause gaps.
• C. These steps are unnecessary.
• D. Compression improves fit and does not affect R-value.

Answer: (B)

Maintaining the full thickness of batt insulation is essential for its performance. The insulating value comes from trapped air within the fibers, which slows heat flow. When batts are compressed to fit a tight space, that air space is reduced, the material becomes denser, and the effective R-value drops. Compression can also create gaps around edges, corners, or around wires, leading to drafts and thermal bridging.

To avoid this, install batts without forcing them into cavities. Cut pieces to fit around obstacles and around outlets, then place them gently so they sit between the framing members without squeezing. Use proper supports—like netting, wire, or batt holders—to hold the insulation in place and preserve the full thickness. Fill irregular spaces with appropriately sized off-cuts rather than compressing the main portions. The goal is a continuous, full-thickness layer that provides the intended R-value and minimizes gaps.