For lapped, nonsoldered seam metal roof panels with applied lap sealant, what is the minimum slope required?

The required minimum slope for lapped, nonsoldered seam metal roof panels using applied lap sealant is indeed 1/2 unit vertical in 12 units horizontal. This specific slope is critical because it helps ensure proper drainage and prevents water from pooling on the roof surface.

A slope of 1/2:12 translates to approximately 4.2 degrees, which is sufficient to allow rainwater and melting snow to flow off the roof effectively, thereby reducing the risk of leaks or water damage at the seams where the panels are lapped together. This configuration is particularly beneficial when using sealants, as it minimizes the stress on the sealants that could lead to failure.

Steeper slopes, such as those suggested by the other choices, are generally not required for this type of metal roofing system. In fact, greater slopes can lead to increased installation complexity and cost without significantly enhancing performance for lapped, nonsoldered seams.