Glossary

Light gauge steel, defined.

Plain-English definitions of the light gauge steel (LGS) and cold-formed steel (CFS) terms used across our work and these guides.

Light gauge steel (LGS): Structural framing made from thin sheets of galvanized steel cold-formed into shapes such as studs, tracks, and joists. Used as the structural skeleton of a building in place of dimensional lumber. Also called cold-formed steel (CFS) or, generically, steel framing.
Cold-formed steel (CFS): The formal engineering name for light gauge steel: steel shaped at room temperature (cold) by roll-forming or pressing, rather than by heating. LGS, CFS, and cold-formed steel framing all refer to the same material; CFS is the term used in the AISI S240 and S100 framing standards.
Steel framing: A general term for a building's structural frame built from steel. In residential, ADU, and mid-rise construction it most often means light gauge (cold-formed) steel framing, as distinct from heavy hot-rolled structural steel. People searching for steel framing, cold-formed steel framing, or light gauge steel framing are describing the same system.
Roll-forming: The manufacturing process that shapes thin sheet steel into structural profiles by passing it through a series of rollers at room temperature.
Slitting: Cutting a wide master coil of steel lengthwise into narrower strips of the exact widths required to roll-form a given profile.
Master coil: A large coil of sheet steel that serves as the raw input to a steel fabrication line, before slitting and roll-forming.
Galvanized steel: Steel coated with zinc to resist corrosion. Light gauge steel framing is typically galvanized for durability.
Stud: A vertical framing member in a wall. In light gauge steel, studs are roll-formed C-shaped sections.
Track: The horizontal member at the top and bottom of a light gauge steel wall that the studs seat into.
Joist: A horizontal framing member that supports a floor or roof. Light gauge steel joists span between walls or beams.
Panelized construction: A method in which wall, floor, and roof panels are fabricated in a factory, shipped flat, and assembled (erected) on site. The process of building in panels is also called panelization.
Volumetric modular: A method in which complete three-dimensional building modules are built in a factory, often with finishes and systems installed, then transported and set on the foundation.
Module: A complete three-dimensional section of a building, such as a room or group of rooms, fabricated in a factory for volumetric modular construction.
Podium (Type III) construction: A mid-rise approach that places several storeys of residential framing over a concrete podium containing parking or retail. Common for mid-rise multifamily.
Wet-room pod: A factory-built bathroom or kitchen module, complete with plumbing and fixtures, that is installed into a building as a finished unit.
Prefabrication: Building components or assemblies in a factory before delivery to the jobsite, rather than building everything in place on site.
Non-combustible: A material that does not ignite, burn, or contribute fuel to a fire. Steel is non-combustible.
Chapter 7A: The long-standing name for California's wildfire construction requirements for buildings in wildland-urban interface (WUI) fire areas and fire hazard severity zones, covering roofing, vents, cladding, glazing, decking, and more. As of January 1, 2026 the requirements moved out of Building Code Chapter 7A into a standalone code, the California Wildland-Urban Interface Code (Title 24, Part 7), but the name Chapter 7A is still used across the industry.
Seismic retrofit: Strengthening an existing building to better resist earthquakes, for example soft-story retrofits of multifamily buildings in California.
Structural steel: Heavy hot-rolled steel members such as beams and columns, distinct from light gauge (cold-formed) steel. The two are often used together in a building.
ADU: Accessory dwelling unit: a secondary home on a residential lot, such as a backyard unit or garage conversion. ADUs can be single-family or part of a multifamily property.

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Read the light gauge steel guides.

Light Gauge Steel: the overview All insights