1. Fire Standards & A1 Classification
What makes a material truly non-combustible? Understanding the classification system is essential for specifiers, architects, and fire engineers selecting a calcium silicate fire board.
Key Takeaways
- A1 Non-Combustible: GF-1100 achieves EN 13501-1 Class A1 and GB 8624 Grade A1 without fire retardant additives — inherently non-combustible by xonotlite chemistry.
- 1100°C Rated: Maximum service temperature 1100°C with endothermic dehydration absorbing ~2,260 kJ/kg, maintaining structural integrity throughout.
- 120-Minute Fire Door Rating: 40mm core achieves EI 120 per GB 12955 Class A; 30mm for EI 60; suitable for steel fire doors, cable barriers, and duct encasement.
- Mingfa Advantage: 34+ years calcium silicate manufacturing since 1991, ISO 9001 certified, ~20 national patents, fire test reports available for all configurations.
Mingfa Lab Verified (2024): All specifications listed are validated through in-house testing at our Shandong QC laboratory per ASTM C518 (thermal conductivity), ASTM C165 (compressive strength), and ASTM C356 (linear shrinkage). Batch test certificates issued with every order. View our testing methodology
EN 13501-1 Classification
The European standard classifies construction products by reaction to fire: A1 (no contribution to fire at any stage, including fully developed), A2 (negligible contribution), B through F (increasing contribution). GF-1100 achieves Class A1 inherently , no fire retardant additives, no halogenated compounds, no intumescent coatings. The material itself cannot burn. Testing confirms zero heat of combustion (PCS ≤2.0 MJ/kg per EN ISO 1716), zero flame spread, zero smoke production, and zero flaming droplets/particles.
GB 8624 Classification
Under Chinese national standard GB 8624, GF-1100 achieves Grade A1 (the highest classification), confirming it as a non-combustible material. This classification is mandatory for fire door core materials and structural fire protection in Chinese building codes. The board also meets GB 12955 requirements for Class A fire doors (120-minute rating with a 40mm core), tested and certified at accredited Chinese fire test laboratories including the Sichuan Fire Science Research Institute.
Endothermic Dehydration Mechanism
GF-1100's fire performance is not chemical trickery , it is physics. The board's xonotlite crystal structure (6CaO·6SiO&sub2·H&sub2O) contains chemically bound water within the crystal lattice. When heated above approximately 400-450°C, this water is released endothermically , absorbing approximately 2,260 kJ per kg of water released. This heat absorption delays temperature rise on the unexposed face, contributing directly to the board's fire resistance rating. After dehydration, the remaining calcium silicate skeleton remains dimensionally stable and structurally intact to 1100°C. Unlike gypsum (which loses all structural integrity when CaSO&sub4·2H&sub2O dehydrates at ~150°C), GF-1100 continues to provide a physical thermal barrier after its chemically bound water is released.
2. GF-1100 Product Specifications
The GF-1100 is a medium-density calcium silicate fire board (350-450 kg/m³) formulated specifically for passive fire protection. It balances thermal insulation, mechanical strength, and workability for fire door manufacturing, structural steel encasement, and fire compartmentation.
| Property | GF-1100 Value | Standard |
|---|---|---|
| Density (dry) | 350-450 kg/m³ | GB/T 10699 |
| Compressive Strength | ≥2 MPa | GB/T 5072 |
| Flexural Strength | ≥1.5 MPa | GB/T 10699 |
| Thermal Conductivity @ 200°C | ~0.09 W/m·K | GB/T 10294 |
| Thermal Conductivity @ 600°C | ~0.14 W/m·K | GB/T 10294 |
| Maximum Service Temperature | 1100°C | , |
| Moisture Content (as supplied) | <10% | GB/T 10699 |
| Fire Classification | A1 (EN 13501-1) / A1 (GB 8624) | EN 13501-1 / GB 8624 |
| Asbestos Content | 0% (asbestos-free) | ISO 22262-1 |
| Linear Shrinkage @ 1100°C | <2% | GB/T 10699 |
| Surface Finish | Sanded both faces, smooth | , |
| Color | Off-white to light grey | , |
References: [1] ASTM C533-17(2023); [2] EN 14306:2015+A1:2018; [3] GB/T 10699. Full certification details
Standard sizes: 1200×600mm and 1000×500mm. Thicknesses: 20, 25, 30, 35, 40, 45, 50, 60mm. Both faces are sanded smooth for direct application of decorative finishes, laminates, or steel face sheet bonding. CNC routing available for door core blanks cut to exact frame dimensions, column casing pieces for specific steel sections, and complex shapes for penetration seals.
3. Fireproof Door Core Application
The largest-volume application for GF-1100 fireproof board is as the core material in steel fire doors. A 40mm GF-1100 core achieves a 120-minute fire integrity and insulation rating when tested to GB 12955 (China) or EN 1634-1 (Europe).
Lighter Than Vermiculite
GF-1100 (350-450 kg/m³) is approximately 20-30% lighter than vermiculite board cores (500-700 kg/m³) at equivalent fire rating. This reduces total door weight, which means lower hinge wear, easier manual operation (important for accessibility/Building Regulations Part M compliance), and the ability to use standard-duty hinges and closers rather than heavy-duty hardware. A typical 2100×900mm fire door with GF-1100 core weighs 55-65 kg versus 70-85 kg with vermiculite core.
Better Screw Retention
A 5mm diameter wood screw in GF-1100 board has a pull-out strength of approximately 200-300 N, versus 50-100 N in gypsum board core. This matters for hardware mounting: hinges, closers, locks, and panic bars must remain securely fixed throughout the door's service life. Loose hardware can compromise fire performance by creating gaps or allowing the door leaf to warp. GF-1100 maintains screw retention even after fire exposure , gypsum crumbles once dehydrated.
Zero Smoke Production
GF-1100 produces zero smoke when heated to any temperature. The only emission is water vapor (steam) from the endothermic dehydration reaction. There are no organic binders, no resins, no halogenated compounds , the board is 100% inorganic after the cellulose processing fibers burn out during manufacture. For fire doors in escape routes, stairwells, and corridors, zero smoke contribution is a critical life-safety requirement. Smoke inhalation, not burns, is the primary cause of fire fatalities.
Precise Thickness Tolerance
GF-1100 board is sanded to ±1mm thickness tolerance. This consistency is essential for reliable fire door fabrication: the steel face sheets must bond to the core across the entire surface, and any thickness variation creates bonding voids that compromise fire performance. CNC-cut door core blanks are supplied to the exact dimensions required for the door manufacturer's frame size, eliminating trimming waste at the door factory.
Tested door configurations: 40mm GF-1100 core in a standard 1.5mm steel-faced door achieves EI 120 (120-minute integrity + insulation) per GB 12955 Class A. 50mm core achieves EI 180 in some configurations. For 60-minute rated doors (EI 60), 30mm core is sufficient. Door sizes: standard blanks supplied for common door sizes; custom blanks for oversized and non-standard doors. Certification: GB 12955 fire test reports available upon request.
4. Structural Steel Fire Protection
Structural steel loses approximately 50% of its yield strength at 550°C. Building codes mandate that structural steel in multi-story buildings maintain load-bearing capacity for 60, 90, or 120 minutes in a fire. GF-1100 fireproof board encasement provides this protection with a dry, mechanical fixing system.
Board Encasement Method
GF-1100 boards are fixed around the steel column or beam to form a box enclosure. The air gap between the board and steel (typically 25-50mm) provides additional insulation. Boards are fixed with steel angles or channels at corners, secured with screws at maximum 250mm centers. Joints sealed with high-temperature inorganic adhesive (sodium silicate based).
Tested Thickness Ratings
For typical H-section columns with section factor ≤150 m&sup-1, tested to ASTM E119 / EN 13381-4: 30mm GF-1100 board → 60-minute fire rating. 50mm GF-1100 board → 120-minute fire rating. Heavier sections with lower section factors may achieve longer ratings at the same thickness. Project-specific assessment available from our technical team , provide section size and required fire rating.
Advantages Over Alternatives
vs. Intumescent paint: No re-coating schedule, weather-independent installation, visible protection thickness. vs. Sprayed cementitious: No mixing/pumping/spraying equipment, no overspray waste, no curing time, consistent factory-controlled thickness. vs. Vermiculite board: Lighter (~20-30%), better screw retention, lower thermal conductivity at equivalent density. GF-1100 also provides physical impact protection to the steel from minor construction traffic.
5. Fire Compartmentation Systems
Beyond doors and structural steel, GF-1100 calcium silicate fire board is used in a range of passive fire protection systems that divide buildings into fire compartments.
Cable Tray Fire Barriers
In industrial buildings, data centers, and power stations, cable trays carry electrical cables through fire compartment walls and floors. GF-1100 board is cut to size on site and assembled into box enclosures around cable trays and busbar trunking. Joints sealed with inorganic adhesive. A 40mm board enclosure provides 120-minute fire integrity (tested to EN 1366-5) for the cables inside, preventing fire spread along the cable route through compartment boundaries.
Ventilation Duct Protection
Ventilation ducts in fire-rated shafts and smoke extraction ducts in car parks and atria require fire-rated encasement (EN 1366-8). 50mm GF-1100 board encasement around a galvanized steel duct achieves 120-minute fire rating (integrity + insulation). The smooth board surface minimizes additional duct pressure drop , important for fan sizing and system balance. Boards are fixed with steel angles, screws at 250mm centers, and joints sealed.
Penetration Seals & Partition Walls
Penetration seals: Where pipes, ducts, or cables pass through fire-rated walls/floors, GF-1100 board is cut to fit tightly around the penetrating service, with remaining gaps filled with intumescent sealant or firestop mortar. Partition walls: Two layers of 25mm board each side of 75mm steel studs with mineral wool in the cavity achieve EI 120. Unlike gypsum, GF-1100 is not degraded by water exposure , important in basements, plant rooms, and areas where pipe bursts are possible.
Project References
St. Maurice fireproof system , European fire door manufacturer using GF-1100 cores. Jinan Weidong residential complex , 2,400 apartment entrance doors across 12 towers, 50mm GF-1100 core, GB 12955 Class A. Zibo bus depot , cable tray fire barriers in an electric bus charging depot, 40mm GF-1100 enclosures, 120-minute rating. Multiple data center projects , cable penetration seals and fire-rated duct enclosures.
6. Installation Guide
GF-1100 calcium silicate fire board installs with standard tools and techniques. Following these guidelines ensures the designed fire rating is achieved in the completed installation.
Cutting
Cut with carbide-tipped circular saw (40-tooth blade), jigsaw with carbide blade, or score-and-snap for boards ≤25mm. Always use dust extraction and wear P2/N95 respiratory protection. Wet cutting suppresses dust. Cut edges that will be exposed should be sealed with a light brush coat of sodium silicate solution or specified edge sealant to prevent moisture absorption.
Fixing with Screws/Studs
For vertical installations (walls, column faces): stainless steel (304 or 316 grade) screws with 40mm diameter washers at 250mm centers, minimum edge distance 25mm. For overhead installations (ceilings, soffits): same spacing, ensure screws are driven into steel framing or studs with adequate pull-out capacity. Screw length: board thickness + 25mm minimum embedment into the substrate. Predrill screw holes slightly oversize to prevent local spalling.
Joint Sealing & Edge Treatment
Joint sealing: All board-to-board joints must be sealed with high-temperature inorganic adhesive (sodium silicate based) to prevent flame and hot gas penetration through gaps. For applications above 400°C service temperature, specify a phosphate-bonded sealant. Edge treatment: Exposed cut edges should be sealed as described above. Board edges at floor level should be protected from standing water. Multi-layer installations: Stagger joints between layers by at least 150mm to prevent aligned joint paths.
Fire Rating Standards Comparison — EN 13501-1, ASTM E84 & GB 8624
Calcium silicate fire board is specified against a set of fire rating standards that vary by market. The table below maps the common standards against each other so procurement teams can translate between specification languages.
| Standard | Classification | Key Requirement | Calcium Silicate Board |
|---|---|---|---|
| EN 13501-1 (EU) | A1 | Non-combustible, no contribution to fire | A1 classified |
| GB 8624 (China) | A1 | Non-combustible building material | A1 classified |
| ASTM E84 (US) | Class A | Flame spread ≤25, smoke developed ≤450 | 0 / 0 |
| BS 476 Part 4/7 (UK) | Class 0 | Non-combustible + low surface spread | Passes |
| ISO 1182 (International) | Non-combustible | No significant temperature rise in furnace test | Passes |
| ASTM E119 (US) | Fire resistance | Time-rated structural protection | 1-4 hours by thickness |
A1 / Class A / Class 0 are not interchangeable terms — they are tested to different methods. A1 (EN 13501-1) and GB 8624 A1 are both non-combustibility classifications; ASTM E84 Class A measures surface flame spread; ASTM E119 measures fire resistance of an assembly over time. Specify the standard that applies in your project jurisdiction.
Fire Door Core Design & Specification
The fire door core is where calcium silicate board's combination of non-combustibility, low thermal conductivity, and dimensional stability earns its specification. Core design decisions affect the door's fire rating, weight, and long-term flatness.
| Core Parameter | GF-1100 Typical | Design Note |
|---|---|---|
| Core density | 350-450 kg/m³ | Balances fire performance, weight, and screw-holding for hardware |
| Core thickness | 25-60 mm | Driven by fire rating target (see rating table below) and door leaf thickness |
| Fire classification | A1 (EN 13501-1) | Contributes zero fuel load and zero smoke in fire |
| Thermal conductivity | ≤0.072 W/m·K @ 100°C | Slows heat transfer through the leaf, protecting the unexposed face |
| Endothermic behavior | Dehydration at 150-200°C | Absorbs heat during early fire phase, delaying temperature rise |
Thickness versus fire rating: a 25mm core in a steel-faced door leaf commonly achieves 60-90 minutes of integrity and insulation under EN 1634-1; 40-50mm cores reach 120 minutes; multi-layer arrangements with 60mm+ cores can reach 180 minutes in tested assemblies. These are indicative relationships — the certified rating always comes from the door manufacturer's full assembly test, and the core board should be specified to the door supplier's tested configuration rather than substituted casually. Substituting a different core density or thickness voids the assembly certification.
Hardware and edge detail: calcium silicate cores hold self-tapping screws reliably at 350-450 kg/m³ density, which matters for hinges and lock bodies. Edge bands, intumescent seals in the frame rebate, and perimeter smoke seals are specified by the door manufacturer. The core board is supplied with square-cut edges and dimensional tolerance ±1mm on length and width, matching door leaf fabrication tolerances.
Marine & Offshore A60 Fire Divisions
On ships and offshore platforms, calcium silicate fire board is used in A-class fire divisions — the SOLAS system of bulkheads and decks that must remain fire-resisting for a defined period while preventing smoke and flame passage.
An A-60 division must maintain structural integrity and temperature limits for 60 minutes in the standard furnace test (IMO FTP Code Part 3, ISO 9705 based). The division typically comprises a steel bulkhead or deck (A-0 basic) plus insulation on one or both sides. Calcium silicate board is specified here because it is non-combustible (contributing nothing to the fire), dimensionally stable under furnace heat, and available in moisture-resistant treated grades for the marine environment. Board thickness for A-60 is determined by the furnace test of the specific assembly; 25-50mm of calcium silicate per side is the common range depending on steel section and test configuration.
Marine-specific requirements: boards used in accommodation and machinery spaces should carry moisture-repellent treatment to survive the humid marine atmosphere without delamination, and all insulation materials in A-class divisions must be certified non-combustible by an IMO-recognized test laboratory. Installation follows the shipyard's approved fire-protection plan: boards are fastened to the steel with pins or clips, joints are staggered, and penetrations (pipes, cables) are sealed with approved fire-stopping materials. See our CUI prevention guide for related corrosion considerations in insulated marine piping.
Installation & Site Acceptance Checklist
Fire board performance depends on installation quality as much as material properties. The checklist below covers the acceptance points that site quality inspectors verify on fire protection installations.
Pre-Installation
- Boards stored off the ground, dry, protected from weather
- Batch certificates match delivered pallet labels
- Substrate / steel primed, clean, free of oil and rust scale
- Approved installation drawing and fire-stop schedule available
During Installation
- Boards cut with carbide tooling; edges square, no crushed corners
- Fixings per drawing (pins/clips density, embedment depth)
- Joints staggered between layers; gaps ≤2mm and filled
- Penetration seals installed per fire-stop schedule
Acceptance
- Layer thickness and board grade match specification
- No visible gaps, cracks, or delamination
- Wet boards (rain exposure) removed and replaced, not dried in place
- Photographic record of each zone before cladding
Common Rejection Points
- Board substitution without certification re-test
- Water-damaged boards installed (hygroscopic material)
- Gaps at corners and penetrations left unsealed
- Insufficient fastener density for vertical spans
Fire Testing Methods Explained
Fire performance claims only mean something when the test method is stated. The three test families most often cited on fire board specifications measure different things, and conflating them is the most common specification error in passive fire protection.
| Test Family | What It Measures | Typical Standard | Result Reported |
|---|---|---|---|
| Reaction to fire | How the material itself behaves in fire: ignitability, flame spread, heat release, smoke | EN 13501-1 (A1-A2/B/C/D), ASTM E84 (Class A-C), GB 8624 (A1-A2/B1) | Material class, e.g. A1 or Class A |
| Fire resistance | How a complete assembly (wall, door, column) performs under the standard furnace curve: integrity, insulation, load-bearing | EN 1634-1 (doors), ASTM E119 / ISO 834 (general assemblies) | Time rating, e.g. EI 120, 2 hours |
| Non-combustibility | Whether the material contributes negligible heat under a small furnace test | ISO 1182, ASTM E136 | Pass / non-combustible |
Reading a specification correctly: "A1 board" (EN 13501-1) is a reaction-to-fire statement about the material — it does not tell you how long a wall built from it survives fire. "2-hour fire resistance" (ASTM E119) is an assembly statement that depends on the full construction: board thickness, steel gauge, insulation, joints, and fixing pattern. A door with a 60mm calcium silicate core is EI 120-certified as a complete assembly by the door manufacturer; the board itself contributes A1 non-combustibility and the assembly's thermal resistance. When your specification mixes these terms, confirm which standard each claim refers to before comparing products.
Fire Protection for Process & Industrial Facilities
Beyond doors and structural steel, industrial facilities use calcium silicate fire board for process-specific protection where its combination of fire performance and temperature resistance adds value over gypsum or cementitious boards.
Process Piping & Valve Protection
Fire-rated enclosures around critical valves, actuators, and instrument lines maintain function during a pool fire. Calcium silicate board at 350-450 kg/m³ provides the thermal barrier, often combined with intumescent sealant at penetrations. Rated enclosures typically achieve 30-60 minutes of function protection (A60-style construction onshore).
Cable Trays & Electrical Rooms
Calcium silicate board lines cable tray enclosures and electrical room walls to protect essential circuits during fire. The board's high melting point (no melt-through at furnace temperatures) and zero smoke contribution make it suitable where halogen-free, low-smoke materials are mandated.
Storage Tank & Spherical Tank Protection
For LPG and flammable liquid storage, fire protection of tank supports and saddles with calcium silicate board slows heat input to the steel, extending the time available before buckling. This application pairs the board with fire-resistant coatings, with the board handling the high-temperature side.
Design note: industrial fire protection is assembly engineering. The board is one component of a rated system that includes fixings, seals, and sometimes coatings. Always specify the complete system against the applicable standard (NFPA 502 for tunnels, API 2218 for storage tank protection, SOLAS for marine) and verify the assembly rating with the system supplier. Mingfa provides material data (thermal conductivity curves, reaction-to-fire classifications) needed for these assembly calculations, and our technical team supports specifiers with the material-side inputs.
Fire Protection for Tunnels & Infrastructure
Tunnel and infrastructure fire protection is one of the most demanding applications for fire board, because the fire load is large, access for repair is difficult, and the consequence of failure is catastrophic. Calcium silicate board is specified in this sector for its combination of A1 non-combustibility, dimensional stability under furnace conditions, and resistance to the humidity and vehicle-generated vibration found in tunnels.
Tunnel linings: road and rail tunnel linings are protected against the RWS (Rijkswaterstaat) and HC (hydrocarbon) fire curves, which reach much higher temperatures faster than the standard cellulosic curve. Calcium silicate board systems, typically 25-60mm in metal-faced panels, are fixed to the tunnel lining to keep the concrete temperature below the spalling threshold. The board's low thermal conductivity delays heat penetration, and its A1 classification contributes no smoke or flame to the tunnel environment — critical for evacuation visibility.
Structural members: bridge piers, steel box girders, and station columns near vehicle traffic receive board cladding to protect structural steel from reaching critical temperature during a fire. The protection is dimensioned using the same assembly logic as building structural protection, but with the tunnel's fire curve substituted for the cellulosic curve, which typically drives thicker boards (40-60mm) for the same time rating.
Specification path: tunnel fire protection is specified under national and project standards — in Europe typically via the national annexes and the Efectis/NFPA guidance, with the RWS curve for Dutch practice and the HC curve for hydrocarbon risk areas. The protection system (board, fixings, joints, and any intumescent seals) is tested as an assembly against the project fire curve. Mingfa supplies the calcium silicate board component with full material data (thermal conductivity curves to 800°C, reaction-to-fire classification, moisture resistance data) for the system integrator's calculations, and supports specifiers with material-side inputs for their assembly testing.
Board Selection Checklist for Fire Protection Specifiers
When specifying calcium silicate fire board, the checklist below prevents the common specification errors found in tender reviews.
- State the standard, not just the rating: write "A1 to EN 13501-1" rather than "A1 fire rated" — the standard defines what the claim means.
- Separate material class from assembly rating: the board is A1; the fire resistance (EI 60/120) belongs to the tested assembly and is certified by the system or door manufacturer.
- Verify density grade: fire door cores, structural cladding, and marine divisions use different densities (350-450 kg/m³ typical); substituting a lower density board changes screw-holding and thermal behavior.
- Check moisture treatment for outdoor/marine: specify water-repellent treated board where the installation may see humidity before cladding.
- Require batch traceability: batch test certificates (density, shrinkage, thermal conductivity) must match the delivered pallet labels.
- Confirm the fire curve: tunnels and hydrocarbon facilities use RWS/HC curves, which drive thicker boards than the standard cellulosic curve for the same time rating.
Applying this checklist at specification stage eliminates the majority of substitution and compliance issues that surface at site acceptance. Mingfa's technical team reviews specifications against these points free of charge and confirms material suitability before quotation.
Mingfa GF-1100 fire board is stocked in standard sizes with custom sizes machined to drawing. Sample boards (A4) are available for evaluation, and batch test certificates ship with every order. For specification support, contact our technical team with your assembly detail and target rating.
Certification documents, MSDS, and technical data sheets are available for download from the technical library.
7. Certification Documents Available
For project specification and regulatory compliance, Mingfa provides comprehensive fire test documentation for the GF-1100 fireproof board.
EN 13501-1 Classification Report
A1 classification confirmed by accredited European fire test laboratory. Includes test data for heat of combustion (EN ISO 1716), non-combustibility furnace test (EN ISO 1182), and single burning item test (EN 13823).
GB 12955 / EN 1634-1 Door Test Reports
Full-scale fire door test reports for 40mm and 50mm GF-1100 core configurations. 120-minute and 180-minute ratings documented. Door construction details, hardware specifications, and installation requirements included.
Structural Steel Protection (EN 13381-4 / ASTM E119)
Fire resistance test reports for GF-1100 encased steel columns and beams. Temperature-time curves, steel temperature data, and assessed thickness/rating tables for different steel section factors.
How to request certificates: Specify which test standards and ratings are relevant to your project. Certificates are provided as PDF documents. A non-disclosure agreement may be required for proprietary test reports. Also available: Material Safety Data Sheet (MSDS), Declaration of Performance (DoP per EU 305/2011 CPR), ISO 9001 certificate, and third-party asbestos-free verification (ISO 22262-1).
For fire door manufacturers: see our dedicated guide for fire door production engineers covering core selection, fabrication, and certification.
Request Quotation & Certification DocumentsAbout the Author — Mingfa Insulation Technical Team
Mingfa Insulation engineering team — 34+ years calcium silicate R&D and manufacturing since 1991. ~20 national patents. lzmfgr@163.com