What is the primary purpose of the paper backing on blanket or batt insulations?

The primary purpose of the paper backing on blanket or batt insulations is to provide a vapor barrier. This backing helps to control moisture in building assemblies, which is essential for preventing issues such as mold growth, wood rot, and a decrease in insulation effectiveness. A vapor barrier restricts the movement of water vapor through walls, ceilings, and floors, protecting the integrity of the building materials and ensuring that the insulation performs optimally.

While there are other considerations when it comes to insulation, such as structural support, appearance, and thermal resistance, the specific role of the paper backing is primarily focused on moisture control. This function is critical in maintaining a healthy indoor environment and ensuring the longevity of both the insulation and the building structure.