The minimum overlap of vertical joints of felt or paper, which is applied to exterior walls as a weather-resistant barrier, is how many inches?

The minimum overlap of vertical joints of felt or paper applied to exterior walls as a weather-resistant barrier is crucial for ensuring the material effectively protects against moisture infiltration. An overlap of not less than 6 inches is specified to create a sufficient barrier that prevents water from seeping through the joints, particularly during heavy rain or adverse weather conditions.

The rationale behind this requirement lies in the need to account for various factors such as wind-driven rain, the potential for material shrinkage over time, and the importance of maintaining a continuous barrier against moisture. A 6-inch overlap provides an adequate margin for error and enhances the overall integrity of the weather-resistant barrier, ensuring that outside moisture does not compromise the building's structure or interior environments.

This practice conforms to industry standards and building codes, which have been developed through numerous studies and practical observations regarding moisture control in building construction. Having a reliable and durable waterproofing layer is essential in maintaining the longevity and performance of any exterior wall system.