Which material is most commonly used as a vapor retarder in faced batts?

Kraft paper is the most commonly used material as a vapor retarder in faced batts due to its effective moisture barrier properties. This paper is often integrated into insulation products, providing a convenient solution that reduces moisture migration from a warmer area to a cooler area, which is crucial in preventing mold growth and structural damage. Kraft paper is cost-effective and serves as a sufficient barrier for vapor control, particularly in residential buildings.

In building construction, managing moisture is critical for maintaining indoor air quality and the integrity of building materials. The faced batts with Kraft paper help to regulate the level of humidity within walls and ceilings, creating a healthier living environment.

Other materials listed, such as plastic sheeting, are also used for vapor barriers but are typically applied in different contexts, such as on the ground in crawl spaces. Aluminum foil is an effective vapor barrier as well but is less common in insulation due to its cost and specific use cases. Fiberglass mesh does not serve as a vapor retarder and is instead used for reinforcement in various applications. Therefore, Kraft paper remains the preferred choice due to its balancing of cost, efficacy, and ease of installation.