What are the most standard sheet steel thicknesses?

Updated February 21, 2017

Sheet steel is metal formed into large, flat pieces and is used worldwide in the construction industry and metalworking. Thickness, or "gauge," of sheet steel varies from around 36- to 3-gauge (thin to thick), although very thin pieces are considered "foils" or "leaves," and pieces thicker than 6 mm (1/4 inches) are referred to as "plates."

Nominal base steel thicknesses

The nominal base steel thickness or "design thickness" is a list of the most commonly supplied standard sheet steel gauges used and supplied to the industry by engineers. It is used to determine the structural properties of the cold-formed steel and appears in product catalogues and load tables. Base steel thickness is the thickness of the steel before application of any additional coatings.

Gauge numbers

The gauge number refers to the thickness of each sheet of steel. It has no units, and is simply a scale of numbers from 3 to 36. Gauge numbers 8, 10, 12, 13, 14, 15, 16, 18, 20, 22, 24, 26, 28, 29 and 30 are the most standard sheet steel thicknesses in the construction industry.

Decimal thickness

Each gauge number has a different measurement of thickness, with units either in inches or in millimetres. The higher the gauge, the thinner the material. For gauges 8, 10, 12, 13, 14, 15, 16, 18, 20, 22, 24, 26, 28, 29 and 30 the thicknesses are 0.1644, 0.1345, 0.1046, 0.0897, 0.0747, 0.0673, 0.0598, 0.0478, 0.0359, 0.0299, 0.0239, 0.0179, 0.0149, 0.0135 and 0.0120 inches, respectively.

Lightweight steel frame

Lightweight sheet steel used for frames also has a list of common, standard thicknesses. For gauges 25, 20 drywall, 20 structural, 18, 16, 14, 12 and 10, the minimum base steel thickness is 0.0179, 0.0296, 0.0329, 0.0428, 0.0538, 0.0677, 0.0966 and 0.1180 inches, respectively.

Consumer products

The most common thicknesses of sheet metal seen by the average consumer, rather than the construction engineer, are 12 and 14 for basic framing applications and 29 for roof panels and side, supportive structures. These standard sheet steel materials are used around the home in, for example, carports.

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About the Author

Natasha Parks has been a professional writer since 2001 with work published online and in book format for "Thomson Reuters," the "World Patents Index" and Her areas of expertise are varied and include physics, biology, genetics and computing, mental health, relationships, family crises and career development. She holds a Bachelor of Science in Biophysics from King's College, London.