How much minimum overlap is required for a 6 mil vapor retarder?

The minimum overlap required for a 6 mil vapor retarder is 6 inches. This specification is established to ensure an effective seal against moisture entering the building envelope. When vapor retarders are installed, overlapping is crucial to prevent any gaps that could allow moisture to penetrate, which can lead to potential problems such as mold growth and damage to building materials. A 6-inch overlap provides a sufficient barrier to enhance the vapor retarder’s effectiveness in controlling moisture movement and maintaining indoor air quality.

In practice, ensuring proper overlap also facilitates the installation process, as it allows for an appropriate amount of material to adhere to itself, which helps maintain its integrity over time. This measure aligns with best practices and codes to promote durable and efficient building construction.