How to Measure the Gauge on Metal Roofs

Steel, galvanized steel, and copper are common metal roofing materials.

Typically, the lower the number of the gauge, the thicker the metal sheet actually is. The Union Corrugating Company website recommends using 24 gauge metal for roofs subject to severe weather conditions; 29 gauge metal is the thinnest suggested for home roofing needs.

1. Set up a ladder against or next to your home or shed. Check that the ladder is positioned in a safe and secure manner prior to climbing it.

2. Look for a section of the roof where you can measure the thickness of the metal roofing from top to bottom. Check at the edges of the roof or between panels.

3. Not all metal roofs are painted. However, if your roof is painted, scrape away a small section of paint near the edge of the metal where the caliper will grip the roofing. Use a wire brush, and avoid scraping away more paint than is necessary to collect the measurement. Brush away the excess dust and paint chips.

4. Close the tips of the caliper jaws around the freed portion of metal roofing. Grip the roofing firmly, but not so tight that the metal is deformed. The jaws' flat edges should lie fully flush against the metal. Record the thickness of the metal.

5. Repeat in several places around the roof if possible. Add the various measurements together, then divide the sum by the number of measurements taken to determine the average thickness of the metal roofing.

6. Consult a metal gauge conversion chart and identify which gauge is closest to the thickness of your metal roofing. Look in the column listing thicknesses for your specific roofing material. Check the 24 to 29 gauge range first, as those are the most common roofing gauges.