What minimum overhang, in inches, should a chimney cap provide?

A chimney cap should provide a minimum overhang of 2 inches to effectively protect the chimney from water infiltration, debris accumulation, and various weather elements. This overhang ensures that rainwater is directed away from the chimney structure, which helps prevent moisture-related problems such as mold growth and deterioration of the chimney materials.

The 2-inch overhang strikes a balance between providing adequate protection while not being excessively large, which could lead to other issues such as wind stress or aesthetic concerns. It's important that the cap extends far enough to shield the flue openings without obstructing them, allowing for proper ventilation while still enhancing the overall integrity of the chimney system.