What is the best fire protection for structural steel?

The best fire protection for structural steel depends on the building type, required fire resistance period, project environment and whether the steel is exposed or concealed. Intumescent coatings are often suitable for visible steelwork where appearance matters, while board systems and spray-applied systems are commonly used for hidden or functional areas. The right option should always be based on the building’s fire strategy, the steel section being protected, relevant test evidence and competent specification.

Why does structural steel need fire protection if steel does not burn?

Steel is non-combustible, but it can still lose strength when exposed to high temperatures. During a fire, unprotected steel can heat rapidly and may lose its ability to support the loads it was designed to carry. Structural steel fire protection slows this heating process, helping beams, columns and frames maintain loadbearing capacity for the required fire resistance period.

What are the main types of structural fireproofing systems?

The main structural fireproofing systems include intumescent coatings, cementitious or fibrous spray-applied systems, and fire encasement boarding. Intumescent coatings are often used where steel is visible and a cleaner finish is needed. Spray-applied systems are useful for large commercial or industrial structures, while board systems provide robust protection where steelwork is concealed or where durability is important.

What is the difference between intumescent coatings and fire encasement boards?

Intumescent coatings are applied directly to the steel and expand when exposed to heat, forming an insulating layer that slows temperature rise. Fire encasement boards are fixed around the steel to physically surround and protect it. Coatings are usually preferred for exposed architectural steelwork, while boards are often used in hidden areas, service spaces, plant rooms or locations where a stronger physical barrier is required.

Are spray-applied systems suitable for commercial and industrial buildings?

Yes, spray-applied structural steel fire protection can be suitable for both commercial and industrial buildings, especially where large areas of steel need to be protected efficiently. These systems are often used in warehouses, car parks, basements, plant areas and large structural frames. They are generally chosen for functional spaces where appearance is less important than speed, coverage and fire performance.

How is the required fire resistance period decided?

The required fire resistance period is usually determined by the building’s fire strategy, use, height, layout, occupancy and relevant Building Regulations guidance. Common requirements may include 30, 60, 90 or 120 minutes of fire resistance. A competent specialist should review the project details and specification before selecting the right fire protection system for structural steel.

Can structural steel fire protection be added to an existing building?

Yes, fire protection for structural steel can often be added or upgraded in existing buildings. This may be required after a fire risk review, refurbishment, change of use, or where previous protection is missing, damaged or no longer suitable. Retrofitting may involve intumescent coatings, board systems or spray-applied protection depending on access, condition of the steelwork and required performance.

What common defects are found in structural steel fire protection?

Common issues include inadequate coating thickness, damaged intumescent coatings, missing protection around connections, poorly fitted boards, gaps in coverage, damaged spray-applied materials, poor surface preparation and lack of supporting documentation. These defects can reduce the effectiveness of the system and may mean the steel does not achieve the required fire resistance period.

Does structural steel fire protection need to be inspected or maintained?

Yes, structural steel fire protection should be inspected as part of ongoing building maintenance, especially after refurbishment, impact damage, water leaks or other works that may disturb the protection. Even durable systems can be compromised over time. Regular inspection helps identify defects early and supports long-term compliance with the building’s fire safety strategy.

Can FIS help choose the right structural steel fire protection system?

Yes, FIS can help assess your building, review the required fire resistance period and recommend a suitable system based on the project environment, finish, durability and compliance needs. Our team can support intumescent coatings, spray-applied systems, fire encasement boarding and remedial works, helping ensure structural steel is protected correctly and in line with the building’s fire strategy.

Structural Steel Fire Protection

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Structural steel fire protection is an essential part of passive fire protection, helping steel columns, beams and loadbearing frames maintain their strength during a fire. Although steel is non-combustible, it can lose loadbearing capacity when exposed to high temperatures. Without suitable protection, this can affect the stability of the structure and increase the risk of building failure.

At Fire Industry Specialists Ltd, we provide fire protection for structural steel in commercial and industrial buildings across the UK. Our team can support new builds, refurbishments, remedial works and wider passive fire protection projects, helping contractors, developers, building owners and facilities managers protect steel structures and meet fire safety requirements.

Whether your project requires intumescent coatings, cementitious or fibrous spray systems, or fire encasement boarding, we can help specify and install the right solution for your building.

What is structural steel fire protection?

Structural steel fire protection refers to the materials and systems used to protect steelwork from heat during a fire. These systems are designed to insulate steel and slow down the rate at which it reaches critical temperatures.

In practical terms, fire protection of steel structures helps loadbearing steel elements retain their strength for a defined period. This may be 30, 60, 90 or 120 minutes, depending on the building’s use, fire strategy and required level of fire resistance.

Typical steel elements requiring protection can include:

columns
beams
trusses
structural frames
mezzanine supports
roof and floor support members

The correct fire protection for steel structures will depend on where the steel is located, whether it is visible or concealed, the required fire rating, and the environmental conditions within the building.

Why does structural steel need fire protection?

Steel is widely used in construction because it is strong, versatile and durable. However, during a fire, unprotected steel can heat up quickly. As its temperature rises, it begins to lose strength and stiffness, which can reduce its ability to support the building.

This makes steel structure fire protection critical for three main reasons.

Protecting life safety: If structural steel remains stable for longer during a fire, occupants have more time to evacuate safely. This is especially important in commercial, industrial, healthcare, education and multi-storey buildings, where evacuation may be more complex.
Maintaining structural integrity: Steel columns and beams often form the main framework of a building. Protecting them helps reduce the risk of structural failure during a fire, supporting the wider fire safety strategy and helping limit damage.
Supporting compliance: Fire protection for structural steel in buildings is often required to meet the fire resistance expectations set out in the building’s design and fire strategy. This may include requirements under Approved Document B, British Standards and project-specific fire engineering guidance.

Fire protection of steel structures: our core systems

Intumescent paint coatings

Intumescent coatings are one of the most common forms of fire protection for structural steel, particularly where the steelwork is visible. The coating is applied to the steel like paint and then finished with a decorative topcoat where required.

During a fire, the intumescent coating reacts to heat and expands to form an insulating char. This layer slows heat transfer and helps the steel maintain its loadbearing capacity for the required period.

Intumescent coatings are often used in:

commercial offices
retail environments
public buildings
exposed architectural steelwork
projects where appearance is important

Cementitious and fibrous spray coatings

Cementitious and fibrous spray systems are commonly used where steelwork is concealed or where a functional finish is acceptable. These systems are applied directly to the steel to create an insulating layer that protects it from high temperatures.

Spray-applied systems are often suitable for large-scale commercial and industrial projects because they can cover significant areas efficiently. They may be used in:

warehouses
industrial units
car parks
basements
plant areas
large commercial structures

Fire encasement boarding

Fire encasement boarding involves surrounding steel elements with fire-resistant boards. This method is often chosen where a robust, defined and durable protective system is required.

Board systems are commonly used for hidden steelwork, service areas, plant rooms, corridors, car parks and areas where impact resistance may be important. They can provide consistent protection when correctly fixed and detailed around joints, corners and connections. Fire encasement boarding can be a strong option where:

steel is concealed within the building fabric
a dry installation method is preferred
durability is important
a more robust physical barrier is needed
the finish does not need to resemble exposed steel

structural-steel-fire-protection

Our structural steel fire protection process

1. Initial review and specification

We begin by reviewing the building requirements, fire strategy, steel layout and required fire resistance rating. Where drawings or project specifications are available, we use these to understand which steel elements require protection and what level of performance is needed.

This stage helps determine whether intumescent coatings, spray-applied systems, encasement boards or a combination of systems is the most suitable option.

2. Surface preparation

Correct surface preparation is essential, particularly for intumescent coatings and spray-applied systems. Steel may need to be cleaned, primed or prepared to ensure the protective system bonds correctly and performs as intended.

Poor preparation can affect adhesion, finish and long-term durability, so this stage is key to a compliant installation.

3. Installation or application

Once the system has been specified and the steel prepared, our team carries out the installation or application in line with manufacturer guidance and relevant test evidence.

This may involve applying intumescent coatings to the required thickness, spraying cementitious or fibrous materials, or fitting fire-resistant boards around steel sections. Attention to detail is essential, particularly around connections, joints, corners and areas where the steel meets other building elements.

4. Inspection, documentation and handover

After installation, the work should be inspected and recorded. This may include visual checks, thickness measurements where applicable, photographic evidence and documentation to support the building’s fire safety records.

Clear documentation helps building owners, contractors and facilities managers demonstrate that fire protection structural steel works have been completed in line with the required specification.

Which structural steel fire protection system is right for your building?

Choosing the right fire protection for steel structure applications depends on several practical and compliance-led factors. No single system is best for every building, so specification should always be based on the fire strategy, site conditions and long-term use of the space. Key considerations include:

the required fire resistance period
whether the steel is exposed or hidden
the desired appearance and finish
internal or external environmental conditions
programme and installation timescales
durability and risk of impact
access for future inspection and maintenance
compatibility with other building materials and finishes
whether the project is commercial, industrial or mixed-use

For visible steelwork, intumescent coatings may be preferred because they provide a more attractive finish. For hidden or high-impact areas, board systems may be more suitable. For large industrial or back-of-house spaces, spray-applied systems may offer a practical and efficient solution.

At FIS, we can help assess your building and recommend a suitable structural steel fire protection system based on performance, compliance and project needs.

Compliance, testing and fire resistance ratings

Structural steel fire protection must be selected and installed in line with the building’s fire strategy, relevant regulations and product test evidence.

In England, Approved Document B provides guidance on fire safety in building design, including fire resistance for structural elements. Depending on the system and project, standards such as BS 476, BS EN 13381 and BS EN 13501 may also be relevant.

It is important that any fire protection for structural steel in buildings is supported by system-specific evidence. This means the product or system should have been tested for the intended application, steel section, protection thickness and required fire resistance period.

Competent specification and installation are essential. If the wrong system is chosen, applied incorrectly or installed without the correct thickness or detailing, the steel may not achieve the required level of protection.

Why choose FIS for structural steel fire protection?

At Fire Industry Specialists Ltd, we provide structural steel fire protection as part of our wider passive fire protection service. Our team understands how steel protection works alongside fire stopping, fire barriers, compartmentation and fire doors to support the overall fire strategy of a building.

We can support your project from initial assessment through to installation and remedial works. Our team can help identify which steel elements require protection, recommend suitable systems, install them correctly and provide practical guidance to support compliance.

As part of the LS Fire Group, we provide UK-wide coverage while maintaining a responsive and specialist service. We work with commercial and industrial clients across a wide range of sectors, including construction, manufacturing, warehousing, education, healthcare, residential and public sector buildings.

Book structural steel fire protection with FIS

Structural steel fire protection plays a vital role in protecting buildings, supporting safe evacuation and helping steel structures maintain their strength during a fire.

Whether your project requires intumescent coatings, spray-applied protection, fire encasement boarding or remedial works to an existing system, FIS can help.

Contact Fire Industry Specialists Ltd today to discuss your structural steel fire protection requirements, arrange a site assessment or speak to our team about the most suitable solution for your building.

Fire safety is a responsibility that never rests and we’re here to implement complete fire protection for your business. Get in touch with our industry-leading experts to learn how we prevent fires, protect lives, and ensure compliance for you.

0333 444 0070

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