Is SFS Fire Rated? Steel Frame Systems Fire Safety & Compliance Explained

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Steel Frame Systems (SFS) are built from non-combustible galvanised steel, which does not burn, ignite or add to the fire load — steel achieves the top Euroclass A1 reaction-to-fire classification. However, the overall fire resistance of an SFS wall (typically 30, 60, 90 or 120 minutes) comes from the complete build-up — the steel studs plus fire-rated boards, mineral wool insulation and cavity barriers — not the steel alone. Correctly specified and installed to a tested system, SFS readily meets UK Building Regulations (Approved Document B), including the stricter rules for high-rise residential buildings introduced after Grenfell.

"Is SFS fire rated?" is one of the most common questions we are asked about Steel Frame Systems — and the honest answer is that it depends on what you mean by "fire rated." The steel itself is non-combustible, but a wall's fire performance is a property of the whole assembly. Below, our design team explains the two different fire concepts that matter, how an SFS wall actually achieves its rating, and why non-combustible SFS systems have become so important in the post-Grenfell regulatory landscape.

Is the Steel in SFS Combustible?

No. The cold-formed galvanised steel used in Steel Frame Systems is non-combustible — it does not burn, ignite, spread flame or release smoke and toxic gases when exposed to fire. Under the European reaction-to-fire classification (BS EN 13501-1), steel achieves Euroclass A1, the highest possible rating, meaning it makes no contribution to the fire load of a building.

This is a fundamental difference from timber frame, where the structural frame itself is combustible and contributes fuel to a fire. With SFS, the load-bearing structure adds nothing to the fire — a property that becomes increasingly valuable as buildings get taller and fire-safety requirements get stricter.

It is worth noting that non-combustible does not mean unaffected by heat. Steel does not burn, but like all structural materials it loses strength as its temperature rises. That is why fire protection is designed into every SFS wall by our design team from the outset, rather than treated as an afterthought.

Reaction to Fire vs Fire Resistance — The Crucial Distinction

Most confusion about SFS fire performance comes from mixing up two separate things. Reaction to fire describes how a material behaves when exposed to fire — whether it ignites and contributes fuel. This is where steel scores its top A1 rating. Fire resistance, by contrast, is measured in minutes and describes how long a complete building element (a wall, floor or compartment) continues to perform its job during a fire.

Fire resistance is assessed against three criteria, often written as R, E and I: load-bearing capacity (R), integrity against the passage of flame and hot gases (E), and insulation against excessive temperature rise on the unexposed face (I). A wall might be rated REI 60, meaning it satisfies all three for 60 minutes.

So when a client asks whether SFS is "fire rated," the technically correct response is that the steel has an excellent reaction-to-fire classification, and the wall as a whole is designed and tested to achieve a specific fire-resistance period appropriate to the building.

How an SFS Wall Achieves Its Fire Rating

An SFS wall earns its fire-resistance rating from the entire build-up working together, not from any single component. A typical fire-rated external or separating wall combines light gauge steel studs and tracks, one or more layers of fire-rated plasterboard (such as Type F / fire-line board) on each face, mineral wool insulation within the stud cavity, and a sheathing board on the external face.

The boards are the primary line of defence: they shield the steel from heat, delaying the temperature rise in the frame and maintaining the insulation and integrity criteria. Adding board layers or specifying thicker, denser boards increases the rating — which is how the same basic steel frame can deliver anything from 30 to 120 minutes of fire resistance.

Crucially, these ratings only hold if the wall is built exactly as the tested system specifies — correct board type, fixing centres, joint treatment and insulation. This is why we supply the specified, certified board and insulation products and why our installation teams build strictly to the approved details. Substituting a cheaper board or widening fixing centres can invalidate the entire rating.

Cavity Barriers, Fire Stopping and Compartmentation

Fire resistance is not only about the face of the wall — it is also about stopping fire and smoke spreading through hidden cavities and around penetrations. SFS walls incorporate cavity barriers at junctions, around openings and at floor levels to close off the routes fire would otherwise travel.

Every service penetration — for pipes, cables, ducts and sockets — must be fire-stopped with a tested product to maintain the wall's integrity. Compartmentation (dividing a building into fire-resisting cells) limits how far a fire can spread and protects escape routes. Getting these details right is as important as the wall build-up itself, and it is a core part of how we design fire-compliant SFS.

SFS and the Post-Grenfell Regulatory Landscape

The 2017 Grenfell Tower fire transformed UK fire regulation, particularly for tall residential buildings. The combustible cladding ban now requires materials in the external walls of relevant high-rise residential buildings to achieve Euroclass A1 or A2-s1,d0 — effectively non-combustible. The Building Safety Act has introduced a much stricter regime of accountability, the "golden thread" of information, and oversight by the Building Safety Regulator for higher-risk buildings.

In this environment, a non-combustible structural system is a significant advantage. Because SFS contributes nothing to the fire load and pairs naturally with non-combustible boards, insulation and cladding, it is well suited to mid-rise and high-rise residential and commercial buildings where the rules are most demanding. It is one of the reasons SFS systems have grown so rapidly in UK construction over the past decade.

Standards and Building Regulations You Should Know

Fire safety for SFS in England is governed primarily by Building Regulations Approved Document B (Fire Safety), with equivalent guidance in the devolved nations. Reaction-to-fire performance is classified under BS EN 13501-1, while fire-resistance test methods follow the BS EN 1364 and BS EN 1365 series (with the older BS 476 parts still referenced in some contexts).

Designers select the required fire-resistance period based on the building's use, height and the role of each element. Our design team works with accredited fire engineers and uses manufacturer-tested system specifications so that every wall, floor and junction has a clear, evidenced route to compliance — and so the "golden thread" of fire information is complete and traceable.

How Basframes Delivers Fire-Compliant SFS

At Basframes we treat fire performance as a design input, not a box to tick at the end. We specify tested wall and floor systems, supply the exact certified products those systems require, and our SMAS and SSIP-accredited installation teams build to the approved details with documented quality control. A dedicated Health & Safety Manager visits every site weekly throughout the programme.

Whether you are planning steel framed houses, a mid-rise residential block or commercial buildings, we can advise on the right fire-resistance strategy and provide the evidence trail your building control body and warranty provider will require. Explore our completed projects or get in touch to discuss the fire requirements of your project.