minimum metal roof pitch
Match the roofing on the covered porch with the main roof. Determine the minimum slope of the roof based on the roofing material. The minimum pitch for shingles is 1:6, which is equivalent to 4 inches rise to 24 inches run. The minimum pitch for a standing seam metal roof is 1:4, or 3 inches rise to 12 inches run. The minimum pitch for roll roofing is 2:12, or 2 inches rise to 12 inches run.