Structural steel is the foundation of modern construction, forming the skeleton of offices, schools, hospitals and residential buildings. Although steel is non-combustible, it rapidly loses strength when exposed to high temperatures, making structural steel fire protection essential to prevent collapse during a fire.
Under UK structural steel fire protection building regulations, every load-bearing element must achieve a specified level of fire resistance to ensure safety and compliance. That’s why effective fire protection for structural steel in buildings is necessary to preserve structural stability, protect lives and reduce damage.
In this guide, we'll explain how to protect structural steel from fire and everything you need to know about fire protection for structural steel in buildings.
How Does Structural Steel React to Fire?
The inherent fire resistance of steel depends on its exposure and the load it carries. Steel begins to deform and lose strength at around 550°C, known as the critical steel temperature, and can melt at approximately 1,500°C. Without adequate protection, this can lead to the collapse of a building during a fire.
It is therefore crucial to ensure structural stability for as long as possible so that emergency services can safely evacuate people from the building and effectively combat the fire. Structural steel fire protection ensures that the structure remains intact, safeguarding both lives and property.
Why Does Structural Steel Protection Matter?
Structural steel is a popular choice in modern construction due to its versatility, strength and durability. It is commonly used in offices, schools, hospitals and residential buildings. Despite its advantages, steel must still be fireproofed to meet steel fire protection requirements under UK building regulations and to ensure it performs effectively during a fire. While structural steel is non-combustible, extreme heat can cause it to lose strength and stiffness. Proper fire protection for structural steel in buildings is therefore essential to maintain structural stability and safety during a fire.
To learn more about why protecting load-bearing steel is essential, read our article on the importance of fire protection of structural steel.
How to Protect Structural Steel From Fire
In most modern buildings, the load-bearing framework consists of steel columns and beams that carry the main structure. The level of protection required depends on the building’s height, use and occupancy.
The most effective way to protect structural steel from fire is through passive fire protection. These systems insulate the steel columns and beams that support the building so they can maintain their strength for a specified period during a fire.
Steel softens at high temperatures, so its load-bearing capacity must be maintained by encasing it in a fire-resistant material. Passive fire protection systems work by slowing heat transfer and delaying structural collapse.
What Are the Main Types of Structural Steel Fire Protection?
There are two main approaches to fire protection for structural steel in buildings: non-reactive and reactive systems.
Non-Reactive Fire Protection
Non-reactive fire protection includes cementitious coatings, plaster or fire-resistant mineral boards that insulate steel from heat. These systems can be spray-applied, trowel-applied or enclosed around the steel members. They are suitable for both internal and external environments and provide a durable form of passive fire protection.
Reactive Fire Protection
Reactive fire protection mainly involves intumescent fire protection for structural steel. Intumescent coatings are paint-like materials that expand at around 250–275°C, forming a thick, insulating char layer that slows heat transfer. Thin-film intumescent coatings are ideal for architectural buildings, while thicker films are often used in industrial or hydrocarbon environments.
Both systems help maintain the temperature of structural steel below critical levels during a fire, preserving its load-bearing capacity for a specified duration. Learn more about how intumescent fire protection for structural steel works in our detailed guide to fire intumescent paint.
Cementitious Coatings
Cementitious coatings are lightweight, spray-applied materials that provide robust thermal insulation to structural steel. They are thicker than intumescent coatings and are often used in industrial environments. This form of structural steel fire protection offers excellent performance for long fire durations.
Fire Boarding
Fire boarding involves attaching fire-resistant boards, such as calcium silicate, gypsum or mineral fibre, around steel members to shield them from direct heat exposure. The thickness and type of board are chosen based on the required fire rating. Once installed, the enclosure creates a sealed barrier that delays heat transfer. Fire boards can also be finished or painted for a clean appearance, making them a practical and aesthetic solution for many projects.
What’s the Best Fire Protection for Exposed or Architectural Steel Beams?
A popular architectural trend is to leave steel beams exposed to create an industrial aesthetic. These visible elements still require protection, and intumescent coatings are the preferred solution.
Intumescent paints appear normal in everyday use but react to heat by expanding, forming a protective layer that insulates the steel. When choosing a product, it’s important to select one tested for fire resistance rather than a coating that only offers surface flame spread protection, as these are not the same thing.
During application, ensure there is adequate space for the coating to expand and avoid surrounding it with combustible materials, as this can limit its effectiveness.
Structural Steel Fire Protection Building Regulations in the UK
Structural steel fire protection building regulations require all load-bearing elements in a structure to achieve a specific fire resistance level. Approved Document B (England and Wales) sets out these standards, typically requiring 30 or 60 minutes of protection, depending on the building’s height and purpose.
Compliance also depends on product testing and certification to confirm suitability for the intended use. All materials used for fire protection of structural steel must meet recognised performance standards to ensure safety and durability.
Additional Guidance
BS 9999: Provides a performance-based approach to fire safety design, allowing flexibility while maintaining protection.
Eurocode 3: Offers calculation methods for determining steel performance under fire conditions, taking into account load and temperature.
Find out more about why compliance with fire protection for structural steel in buildings should be a priority for businesses for safety and regulation.
How Often Should Structural Steel Fire Protection Be Inspected and Maintained?
Structural steel fire protection should be inspected at least once a year by qualified fire professionals. For systems like intumescent coatings, inspections every one to two years are recommended. The exact frequency can depend on environmental conditions, building use and coating type.
Regular inspections identify issues such as mechanical damage, corrosion or coating failure, allowing timely maintenance. Professional assessment helps confirm that your fire protection for structural steel in buildings continues to perform as designed.
A professional inspection service should begin with a detailed evaluation by trained fire engineers. Based on their findings, they will recommend the best measures to maintain compliance and ensure your building remains protected in a fire situation.
Structural Steel Fire Protection at GRJ Contracting
At GRJ Contracting, we have over 30 years of experience designing, supplying and installing passive fire protection systems across the UK. One of our areas of expertise is delivering compliant solutions for the fire protection of structural steel within buildings of all sizes. If you are seeking fire protection for structural steel in buildings for a new‑build project or need remedial works to meet the structural steel fire protection building regulations, our team of certified installers and fire engineers can help. We work to the highest industry standards, holding Kiwa IFC, ASFP and ISO 9001 accreditations to ensure our solutions meet the strictest requirements.
For reliable, professional service you can trust, contact GRJ Contracting today and secure your building with our structural steel fire protection services.
Share this post:
