Q: What does the “gauge” of the metal mean? A: The gauge is a measure of the thickness of the metal, but it’s important to remember that the metal increases in thickness as the gauge numbers decrease. Union offers several gauge options. Listed in order from thinnest to thickest, they are Utility, Econ 29, 29, 26, and 24. It’s important to note that 29 gauge is the thinnest metal recommended for residential applications. Our heavy duty 24 gauge is recommended for those areas with severe weather, high winds, or hail.