When performing inspections of cold-formed steel framing, one of the most obvious things to check for is the material thickness (mils or gauge). Some experienced tradespeople can tell the difference between standard thicknesses by feel alone. Less experienced folks must rely on other methods. Metal stud manufacturers are required to stamp the stud size and gauge on each product.
For instance, Clark Dietrich studs label 6-inch, 16-gauge studs with CD600S162-54 50 KSI. This tells you the stud is 6 inches wide with a 1-5/8 inch (1.62 inch) flange and is 16-ga (54 mils) thick. Lastly, it shows the steel strength to be 50 ksi. However, some studs are cut or positioned in a fashion that makes reading these labels difficult. In those cases, inspectors can look for paint markings. Before leaving the factory, ends of steel studs and tracks are painted with color markings to indicate thicknesses. For example, green paint indicates 16-ga (54 mils) and yellow paint indicates 18-ga (43-mils). If no identifying marks are visible, one can use a micrometer to measure the material thickness. We recommend using a C-shaped outside micrometer. Inside micrometers are hard to use with the rounded, sheared edges of cold-formed steel, making reliable measurements difficult. Take multiple measurements to gain confidence that you have accurately estimated the thickness.
There are several metal thickness gauges available online. Unfortunately, most of these gauges are for sheet metal thicknesses and not for cold-formed structural steel. Still, they can get you close enough to allow you to make a good judgement about the thickness. It is best to make measurements at the stud knockouts and away from rolled edges.
When all else fails, remember these common thickness reference materials that you might have in your pocket.
A quarter is 0.069 inches thick, roughly 14-ga
A dime is 0.053 inches thick, roughly 16-ga
- Blue – 118 mils (10-ga)
- Red – 97 mils (12-ga)
- Orange – 68 mils (14-ga)
- Green – 54 mils (16-ga)
- Yellow – 43 mils (18-ga)
- White – 33 mils (20-ga)
- Pink – 30 mils (20-ga; interior only)
- Black – 27 mils (22-ga)