What is the minimum horizontal overlap required for building paper?

The minimum horizontal overlap required for building paper is 100mm or 4 inches. This specification is essential to ensure that the building paper effectively acts as a barrier against moisture infiltration. Proper overlap helps to direct water away from the seams and prevents dampness that could lead to mold and structural damage.

When the building paper overlaps by the specified amount, it enhances the overall durability and function of the weather-resistive barrier. A sufficient overlap also ensures that the seams are not exposed, reducing the risk of water penetration at the joints. The choice of 100mm aligns with industry standards aimed at providing adequate protection for the underlying structures in various weather conditions.

In contrast, lesser overlaps would not provide the same level of protection, as they could leave gaps in the moisture barrier. This could potentially compromise the integrity of the building envelope over time. Thus, ensuring a 100mm overlap is a code requirement that underscores the importance of adhering to standards for building practices.