What is the minimum slope for lapped, non-soldered seam metal roofs with applied lap sealant?

The minimum slope for lapped, non-soldered seam metal roofs with applied lap sealant is established to ensure proper water drainage and to minimize the potential for water infiltration. A slope of 1/2 inch per 12 inches (which is about 4.2 degrees) is often adequate for these types of roofs because it allows for a slight pitch that helps direct water away from seams and joints.

This slope is significant, especially in regions that may not experience heavy rainfall; it still allows for effective water runoff while also accommodating the use of lap sealant to enhance waterproofing at the seams. In roofing applications, maintaining this minimum slope helps prevent water pooling, which could lead to seam failure and leaks over time.

Higher slopes, such as 2 in 12 or 3 in 12, are often recommended for different types of roofing systems or materials, particularly those not utilizing sealants or where enhanced drainage is necessary. However, for lapped, non-soldered metal roofs with the appropriate use of lap sealant, the 1/2 in 12 slope is specifically designed to strike a balance between functionality and practicality.