What is the appropriate seam lap distance for stapling 15lb asphalt building paper to the subfloor?

The appropriate seam lap distance for stapling 15lb asphalt building paper to the subfloor is 2 to 4 inches. This lap distance is crucial for ensuring that the seams of the building paper overlap sufficiently to prevent moisture infiltration, which can lead to damage or deterioration of the subfloor material. A proper overlap creates a continuous barrier against moisture, thereby enhancing the overall durability and effectiveness of the building paper in shielding the subfloor from water-related issues.

Using a seam lap within this range ensures that the joints remain secure while still allowing for ease of installation. It strikes a balance between providing enough coverage to protect the seams and minimizing waste of the building paper. Laps that are too small may not provide adequate protection, while laps that are too large could lead to unnecessary material use without additional benefit. Hence, a 2 to 4 inch lap distance is standard practice in the industry.