For round metal ducts in a single dwelling unit of 16" size, what gauge should they be?

For round metal ducts that are 16 inches in diameter, the appropriate gauge is 26 gauge. The selection of duct gauge is critical because it affects both the strength and the efficiency of the duct system. In residential applications, the gauge is determined by the size of the duct; as the diameter increases, a lighter gauge can still provide the necessary strength while optimizing airflow.

In the case of a 16-inch round duct, 26 gauge strikes the right balance between durability and weight. Thicker gauges, such as 24 or 22, may be unnecessarily heavy for this size, potentially adding to installation complexity and cost without providing significant benefits. Conversely, 28 gauge is too thin for this application; it may not adequately maintain structural integrity or withstand high airflow pressures, leading to potential issues like deformation or air leakage. Thus, 26 gauge is the optimal choice for a 16-inch round metal duct in a single dwelling unit.