What is the purpose of the paper backing on a batt of insulation?

What is the purpose of the paper backing on a batt of insulation?

• A. to keep the batt from sagging
• B. To refuse the flame spread
• C. to hold the batt together
• D. to form a vapor barrier

Answer: (D)

The main idea is moisture control in wall assemblies. The paper backing on batt insulation acts as a vapor barrier on the interior side, slowing the movement of water vapor into the wall cavity. This helps prevent condensation on cold surfaces, reducing the risk of mold and wood rot. It isn’t meant to stop flames, hold the batt together, or prevent sagging—the stapling aid is secondary to its primary role as a vapor barrier.

The main idea is moisture control in wall assemblies. The paper backing on batt insulation acts as a vapor barrier on the interior side, slowing the movement of water vapor into the wall cavity. This helps prevent condensation on cold surfaces, reducing the risk of mold and wood rot. It isn’t meant to stop flames, hold the batt together, or prevent sagging—the stapling aid is secondary to its primary role as a vapor barrier.