防火・耐火等級基準は鉄骨構造建築物にどのように適用されますか？

Why Fire Protection Matters for Steel Structure Buildings

Steel is one of the most widely used construction materials in the world, prized for its strength, speed of assembly, and adaptability. But there is a critical fact every project owner and procurement manager must understand: structural steel loses approximately 50% of its load-bearing capacity at 550°C — a temperature that a typical building fire can reach within the first 5 to 10 minutes. Without proper fire protection measures, a Steel Structure Building can suffer progressive collapse far sooner than most people expect.

This is why fire safety is not an optional add-on but a mandatory engineering requirement embedded in every major building code worldwide. Whether you are planning a Prefabricated Steel Building for manufacturing, a Steel Warehouse for logistics, or a multi-span Steel Workshop for heavy industry, understanding fire rating standards helps you specify the right materials, pass inspections, and protect both your investment and the people inside.

Jidian Construction Materials Co., Ltd., based in Xiamen, Fujian, China, has participated in the formulation and review of China's national steel structure standards and specifications. With an annual steel structure capacity of 360,000 tons and more than 2,000 completed projects across 50+ countries, we integrate fire protection engineering into every stage of design, manufacturing, and construction. This article breaks down the key fire rating standards, protection methods, and compliance considerations you need to know before placing your next order.der.

Understanding Fire Resistance Ratings: What Do the Numbers Mean?

Fire resistance rating — often expressed in hours — measures how long a structural element can maintain its load-bearing capacity, integrity, and insulation properties under standard fire conditions. The most commonly referenced standards include:

• GB 50016 (China): Code for Fire Protection Design of Buildings, which classifies building fire resistance into four levels — Level I through Level IV — with Level I offering the highest protection.
• EN 13501 (Europe): Classifies construction products by reaction-to-fire (A1 to F) and fire resistance (R, E, I ratings with time periods like R30, R60, R90, R120).
• ASTM E119 (United States): Standard fire test method that assigns hourly ratings (1-hour, 2-hour, 3-hour, 4-hour) to structural assemblies.
• ISO 834 (International): Standard fire resistance test adopted by many countries as the basis for their national codes.

For a typical Industrial Building, the required fire resistance rating depends on the building's occupancy category, height, floor area, and the presence of hazardous materials. For example, a single-story steel workshop with non-hazardous operations may require only a 1-hour rating for primary structural members, while a multi-story warehouse storing flammable goods may demand 2-hour or even 3-hour protection for columns and beams.ams.

Key Fire Protection Methods for Steel Structures

There are three primary approaches to protecting structural steel against fire, each with distinct cost, performance, and application characteristics:

1. Intumescent Coatings

Intumescent paint expands when exposed to high temperatures, forming a thick insulating char layer that slows heat transfer to the steel substrate. These coatings are widely used where aesthetics matter or where space is limited. Typical dry film thickness ranges from 1 mm to 5 mm depending on the target rating, and they can achieve fire resistance periods from 30 minutes up to 120 minutes. For a Prefabricated Steel Building with exposed architectural steel, intumescent coatings offer a clean, visually acceptable solution.

2. Board and Blanket Systems

Fire-rated boards (such as calcium silicate or gypsum boards) and mineral wool blankets encase the steel member, creating a physical barrier against heat. Board systems are durable and suitable for areas prone to impact or abrasion. They are commonly specified in Steel Warehouse environments where forklifts and machinery may damage softer coatings. A typical board enclosure can achieve 1- to 4-hour fire ratings depending on the number of layers and board thickness.

3. Sprayed Fire-Resistive Materials (SFRM)

SFRM — including cementitious sprays and mineral fiber sprays — is the most cost-effective method for achieving high fire ratings on large steel members. It is widely applied in industrial facilities, power plants, and large-span structures. The thickness required depends on the steel section factor (Hp/A ratio), target rating, and the specific product's tested performance. Jidian's portal frame industrial steel workshops, for instance, use ce, use rock wool panels with ≥2-hour fire resistance, combining enclosure and fire protection in a single system.

How to Determine the Right Fire Rating for Your Project

Selecting the appropriate fire rating is not a one-size-fits-all decision. Several factors influence the requirement:

• Building occupancy and function: A power plant, chemical storage facility, or aircraft hangar carries far higher fire risk than a standard distribution warehouse. Each occupancy type triggers different code requirements.
• Building height and footprint: Taller and larger buildings generally require higher fire resistance ratings for primary structural elements to allow safe evacuation and firefighting access.
• Local code jurisdiction: Your project site's national or regional building code dictates minimum requirements. Projects in the Middle East may follow Civil Defense codes, while those in the EU must comply with EN standards, and U.S. projects adhere to IBC and ASTM.STM.
• Insurance requirements: Even when local codes set a baseline, insurance underwriters may mandate stricter fire protection to reduce risk premiums. Always confirm with your insurer early in the design phase.
• Owner specifications: Some project owners specify fire ratings above code minimums to enhance safety, protect high-value contents, or future-proof the facility for regulatory changes.

For a Steel Workshop housing overhead cranes and heavy machinery, fire protection design must also account for the structural implications of crane-induced vibrations on coatings and board systems over time. Jidian's crane-rated steel workshops, designed for 10-50 ton bridge cranes, incorporate fatigue-rated welds per GB 50017 and ISO 10721 — and the fire protection system must be equally durable to match the structure's service life.ce life.

Common Fire Protection Mistakes in Steel Building Projects

In our experience delivering steel structures across Southeast Asia, Africa, the Middle East, and Latin America, we have seen several recurring mistakes that compromise fire safety:

• Treating fire protection as an afterthought: Fire protection should be specified during the structural design phase, not added after fabrication. Retrofitting coatings or boards can conflict with connection details, clearances, and finishing schedules.
• Underestimating the section factor: Thinner steel sections have a higher Hp/A ratio and heat up faster, requiring thicker protection. Using the same coating thickness across all members regardless of section size is a common error.
• Ignoring topcoat compatibility: Some intumescent coatings require a compatible topcoat for weather resistance. Using the wrong topcoat can compromise the coating's expansion behavior.ior.
• Inadequate surface preparation: Fire-rated coatings require proper surface preparation — typically Sa 2.5 blasting — and a qualified primer. Poor preparation leads to delamination and loss of fire protection within years.
• Neglecting maintenance inspection: Fire protection systems degrade over time. Without periodic inspection and repair of damaged areas, the effective fire rating may drop below the designed level well before the building's end of life.ife.

Fire Protection and Prefabricated Steel Building Design: An Integrated Approach

The advantage of a Prefabricated Steel Building lies in its precision engineering and controlled factory environment. Fire protection can — and should — be integrated into the fabrication process rather than treated as a separate site activity. At Jidian, our fabrication follows ISO 15614 welding qualifications and achieves ±2 mm fabrication tolerance with 100% ultrasonic testing on primary welds. This level of precision matters for fire protection because:

• Consistent member dimensions ensure uniform coating thickness and predictable fire performance.
• Pre-engineered connection details accommodate required fireproofing clearances without field modifications.
• Factory-applied primers and base coats provide a controlled surface for subsequent fire-rated coatings applied on site.
• Enclosure systems like rock wool panels serve dual functions — thermal insulation and fire resistance — reducing installation time and total project cost.

This integrated approach is particularly valuable for an Industrial Building where schedule compression is critical. By combining structural steel fabrication with pre-engineered fire-rated enclosure systems, Jidian has delivered portal frame workshops with clear spans up to 36 meters and erection timelines of 25-30 days — all while meeting ≥2-hour fire resistance requirements.

International Compliance: Navigating Multiple Standards

For B2B buyers sourcing steel structures internationally, fire protection compliance can be complex. A single project may need to satisfy the building code of the destination country, the insurance underwriter's requirements, and the manufacturer's quality system. Key considerations include:include:

• Documentation: Request fire test reports from accredited laboratories for all fire-rated materials. Jidian's products carry ISO 9001, CE, SGS, and BV certifications, and we provide full material traceability for every project.ect.
• Code mapping: A 2-hour rating under ASTM E119 is not automatically equivalent to an R120 classification under EN 13501. Work with your supplier's engineering team to map requirements correctly.tly.
• On-site inspection: Many jurisdictions require third-party inspection of applied fire protection. Confirm whether your supplier can coordinate with local inspection authorities or arrange international third-party verification.
• Maintenance manuals: A complete fire protection handover should include maintenance instructions, repair procedures for damaged areas, and inspection intervals to ensure long-term compliance.

Frequently Asked Questions

What fire rating do I need for my steel warehouse?

It depends on your building's occupancy, height, floor area, and local code. A single-story ory Steel Warehouse storing non-combustible goods typically requires a 1- to 2-hour rating for primary structural members. Warehouses with high-piled combustible storage may require 2- to 3-hour ratings. Always confirm with your local building authority and fire protection engineer.

Can fireproofing be applied in the factory before shipment?

Some systems — such as primers and base coats — can be factory-applied. However, most intumescent coatings and SFRM are applied on site after erection to avoid damage during transport and bolting. Board systems are typically installed after the steel frame is complete. Discuss the sequencing with your supplier during the design phase.

How does fire protection affect the cost of a prefabricated steel building?

Fire protection typically adds 5-15% to the structural steel cost, depending on the method and target rating. Intumescent coatings are generally the most expensive per square meter, while SFRM is the most economical for high ratings. Rock wool panel enclosures can offset costs by replacing separate insulation and cladding systems.

Does Jidian provide fire protection design as part of the package?

Yes. As a company that participated in the formulation of China's national steel structure standards, Jidian integrates fire protection engineering into the structural design from the outset. We provide structural calculations for building permits, including fire resistance design, and supply fire-rated enclosure systems such as rock wool panels with documented ≥2-hour fire resistance.nce.

Conclusion: Build Fire Safety Into Your Steel Structure From Day One

Fire protection is not a finish-line task — it is a core engineering discipline that runs parallel to structural design, fabrication, and construction. By understanding the relevant fire rating standards, selecting the right protection method, and working with a supplier who integrates fire safety into every stage, you ensure that your Steel Structure Building meets code, passes inspection, and stands strong when it matters most.

At Jidian Construction Materials Co., Ltd., we bring decades of steel structure expertise, national-standard participation, and a 360,000-ton annual capacity to every project. Whether you need a fire-rated Steel Workshop, a large-span Steel Warehouse, or a custom Industrial Building solution, our engineering team is ready to help you navigate fire protection requirements from specification to handover.

Ready to discuss fire protection for your next steel structure project? Contact Jidian Construction Materials Co., Ltd. for a customized proposal with full fire resistance documentation and structural calculations.