What is the required overlap for vapor retarders?

The required overlap for vapor retarders is 6 inches. This measurement is crucial for ensuring the effectiveness of the vapor retarder in preventing moisture migration within wall assemblies, ceilings, and floors. Proper overlapping helps create a continuous barrier against moisture, which can lead to problems such as mold growth and deterioration of building materials.

Using a 6-inch overlap helps to achieve the necessary performance requirements according to building codes, which aim to maintain the integrity and durability of the structure. A smaller overlap may not provide adequate protection, while a larger overlap, while not incorrect, may be unnecessarily excessive and could complicate installation without providing additional benefits. Therefore, following the 6-inch overlap guideline is essential for compliance with the code and protection of the building.