By the LGS FrameX Team · Updated October 2026
A common question from owners and builders: is steel framing fireproof? The accurate answer is that steel does not burn, but fire resistance is a property of the whole assembly.
Non-combustible is not the same as fireproof
Steel does not ignite or add fuel to a fire, which is why cold-formed steel is accepted in non-combustible construction types under the building code. But steel loses strength at high temperature, so fire-rated walls and floors rely on protection such as gypsum board layers and listed assembly details.
Fire-rated assemblies
Ratings of one hour, two hours and more are obtained from tested assemblies published by testing agencies and listing bodies. The designer selects an assembly that includes the stud size, board type and layers, fasteners and insulation, and the contractor must build it exactly as listed.
Practical tips
Keep penetrations sealed with listed firestop systems, follow the assembly listing for fastener spacing, and do not substitute materials without approval. Local officials make the final call, so involve them early.
How fire resistance is tested
Fire-resistance ratings come from standardized furnace tests. In the United States the common reference is ASTM E119, which exposes a wall or floor assembly to a controlled heating curve and measures how long it keeps its structural capacity, resists the passage of flame and limits temperature rise on the unexposed side. Results are published by listing bodies as tested assemblies that include the exact stud size, board type, number of layers, fastener spacing and insulation.
What happens to steel at high temperature
Steel does not burn, but its strength drops as temperature rises, and thin cold-formed members heat up quickly. That is why load-bearing steel walls and floors rely on protection, most often layers of fire-rated gypsum board, to keep the steel cool for the required time. Unprotected steel is not a rated assembly.
Details that make or break a rating
Small details matter. Board joints must be staggered as listed, fasteners must be the specified type and spacing, and penetrations for pipes, ducts and cables must be sealed with listed firestop systems. Replacing a listed insulation type or cutting back board at a corner can void the tested assembly. Construction teams should keep the listing document on site and inspectors should compare the work against it.
Steel and fire in context
Compared with wood framing, steel adds no fuel to a fire and does not char, which can simplify some code paths and is one reason it is used in multi-family and commercial buildings. It does not replace sprinklers, fire alarms, compartmentation or good egress design, which work together to protect people and property.
Frequently asked questions
Does steel framing burn?
No. Steel is non-combustible and does not feed a fire, but it needs protection in fire-rated assemblies.
How do steel walls get a fire rating?
Through tested assemblies that combine steel studs with gypsum board and other listed components.
Is steel framing allowed in non-combustible construction?
Cold-formed steel is a non-combustible material under the code, subject to the specific provisions and your local authority.
Related guides
Talk to LGS FrameX about your project
Tell us your building type, height and timeline, and our team will help you choose the right light gauge steel framing approach or Fx series machine.
