What is the main purpose of the paper that is stapled with batt insulation?

The paper that is stapled with batt insulation serves primarily to support the insulation material. This backing helps maintain the shape and position of the insulation within wall cavities, attics, or other areas where it is installed. By providing stability, the paper ensures that the insulation remains effective by preventing it from sagging or shifting, which can create gaps that reduce its thermal performance.

While vapor barriers and moisture prevention are important considerations in insulation applications, those functions typically relate to materials specifically designed for that purpose, such as polyethylene sheeting, rather than the paper backing of batt insulation itself. Enhanced thermal resistance is a characteristic of the insulation material itself, rather than the supporting paper. Therefore, the supporting role of the paper is crucial for effectively maintaining the insulation's performance.