Structural Steel Protection
Structural fire protection: protect the member to the project requirement, not to a generic coating thickness.
Overview
Fire Rated Systems delivers passive fire protection to structural steel across new construction, refurbishment and existing buildings — vermiculite spray, intumescent coating and board encasement. The right system depends on the steel member, required fire performance, section geometry, design inputs, exposure, environment, finish, and the evidence supporting the proposed protection system.
Start with the design information
A useful structural-fire enquiry starts with the structural drawings, the fire-resistance requirement, the member schedule, and the protection system proposed or specified. If section factors, design temperatures or coating schedules already exist, send them. If they do not, tell us what information you have and we will identify what still needs design input before pricing or installation can be finalised.
What FRS can take on
- Sprayed and cementitious fire protection to structural steel.
- Intumescent coating systems, installed to the product evidence for the member and the rating.
- Board encasement or boxed protection where the tested or assessed system suits the condition.
- Repairs to damaged or incomplete protection where the original system and a supported repair path can be established — and where the material question has been resolved first, on any building of the relevant era.
- Coordination around interfaces with walls, ceilings, services and penetrations.
- QA photographs, member identification and thickness records for every member we protect.
Sprayed and cementitious protection
Sprayed fire protection forms an insulating layer around the steel member. The required thickness is not a universal number: it depends on the test evidence, member geometry, required fire resistance, design assumptions and the protection material. Surface condition, fixings or reinforcement where required, application thickness and curing all belong in the installation record.
Intumescent coatings
Intumescent coatings — intumescent paint, on most drawings and on most sites — are thin-film systems that expand when heated and form an insulating char. Their use depends on the tested or assessed system, the steel member and the design requirement, as well as primer compatibility, environmental exposure, dry-film thickness and any topcoat or finish requirement. A paint colour or a product name is not enough to establish the required build-up.
Board encasement
Board systems protect steel by enclosing the member in a tested construction. Board type, thickness, layer arrangement, framing or fixing method, joints, member geometry and interfaces all matter. The detail has to remain supportable where it meets walls, ceilings, penetrations or other construction.
Older sprayed protection and asbestos
Sprayed fire protection applied to structural steel between the 1930s and the 1970s can contain asbestos. It was used for exactly this purpose — insulating steel beams and columns — and some of those products were largely asbestos fibre.
This matters more than it does with most asbestos-containing materials, because sprayed coatings are friable. A bonded sheet has to be cut or drilled before it releases fibres. Sprayed protection can release them when it is brushed, knocked, or simply disturbed by work happening nearby.
So on any building of that era, the material question comes first and the fire-protection question comes second. Do not scrape, sand, drill or take a sample of damaged or suspect sprayed protection to find out what it is. Do not send a trade up there to patch it. Check the building's asbestos register, and if the material status is not established, treat it as asbestos until the appropriate assessment says otherwise.
Send us photographs taken without disturbing anything, the building age, the asbestos register if there is one, and any records of the original protection system. We will tell you what can be established from that, what needs assessment, and how the fire-protection scope and the material scope are planned around each other.
Technical library
Structural protection guides.
Can damaged structural fire protection be repaired?
Often, if the existing system can be identified and its repair instructions or supporting evidence cover the damage. A patch is not automatically valid just because it uses the same-looking material.
Scott CunninghamCan old sprayed fire protection on structural steel contain asbestos?
Yes. Sprayed coatings applied to steel between roughly the 1930s and the 1970s were often asbestos-based, and fire protection of beams and columns was one of their main uses. Appearance alone cannot tell you. Because sprayed coatings are friable, the safest assumption on a building of that era is that the material is asbestos until an assessment says otherwise.
Scott CunninghamHow does structural steel fire protection work?
Steel loses strength as it heats. Protection systems slow that heating so the member holds its required performance for the required period. The system is selected against the member, the design requirement and the supporting evidence — not against a general idea of thickness.
Scott CunninghamHow is the required thickness of steel fire protection determined?
Required thickness comes from the system's test or assessment evidence read against the member and the design requirement. There is no universal table, and any figure published without its system and conditions is misleading.
Scott CunninghamSprayed protection, intumescent coating or board encasement: what is the difference?
Sprayed, intumescent and board systems solve the same problem differently, and differ in cost, appearance, application conditions, environmental tolerance, programme and the evidence behind them. The choice is a design decision, not a finish preference.
Scott CunninghamWhat is a steel section factor and why does it matter?
A section factor expresses how much heated surface a steel member has relative to how much steel there is to absorb the heat — in Australian practice the exposed surface area divided by the mass of the member, expressed in square metres per tonne. European and ISO documents use a surface-area-to-volume form instead, so a figure taken from an overseas source is not directly comparable with the tables in an Australian assessment. A high section factor means a member heats quickly for its size and needs more protection; a low one means the opposite. It is one of the inputs that determines the protection thickness required, alongside the design requirement and the tested system. Who establishes it on a given project is a responsibility question rather than a technical one, and it is worth settling early.
Scott CunninghamQuestions
Frequently asked questions
- How thick does vermiculite or cementitious spray need to be?
- There is no useful universal thickness. The required build-up depends on the member and the system design. Send the member schedule and whatever product or system information you have.
- Can you use intumescent instead of sprayed protection?
- Sometimes, but it is a design and system-selection question, not a cosmetic substitution. The member, required fire performance, environment, finish, programme and supporting evidence all have to work.
- Can damaged fire protection be patched?
- Often, where the existing system can be identified and a supported repair method exists. If the material or original system cannot be established, the repair path needs technical review — and on an older building, the material question comes first.
- Our building is from the 1970s and the spray is damaged. What do we do first?
- Nothing to the spray. Sprayed fire protection from that era can be asbestos, and it is friable, so disturbing it is the thing to avoid. Check the asbestos register, photograph the condition from a distance, and send us what you have. We will work out the sequence with you.
- Do you calculate the steel section factor?
- Send the structural and fire information you have and we will tell you what we can work from. Where a member needs a section factor calculated, we will say so and tell you who has to produce it, before it holds up the programme.
Drawings, photos or a defect report in front of you?
Send what you already have. We will tell you what else is needed before the work can be reviewed, priced or booked for site inspection.