A1 Non-Combustible Calcium Silicate Fireproof Board: Applications and Specifications

Published: 2026-07-07 | By Mingfa Technical Team

Passive fire protection is the built-in, material-based defense against fire spread. It does not rely on detectors, pumps, or human action. It works by compartmentalizing a building or industrial structure so that fire cannot propagate freely from one zone to another during the critical evacuation and firefighting period. The materials used in passive fire protection systems must satisfy two distinct requirements: they must not contribute fuel or smoke to the fire (reaction to fire), and they must maintain their barrier function for a specified duration under standardized fire exposure (fire resistance). Calcium silicate fireproof board satisfies both, with an A1 reaction-to-fire classification and fire resistance durations from 30 to 180 minutes depending on board thickness and assembly design.

Mingfa Insulation, established in 1991 in Laizhou, Shandong Province, produces the GF-1100 Super Calcium Silicate Fireproof Board at its 108,000-square-meter factory. The product is EN 13501-1 A1 classified, 100 percent asbestos-free, and supported by test data from third-party laboratories. This article covers the fire rating system, the GF-1100 product specifications, and the four principal application areas: fire door cores, structural steel protection, fire compartmentation, and the relevant installation and testing standards.

1. Understanding Fire Ratings: A1, A2, and Fire Resistance

European standard EN 13501-1 classifies construction products by their reaction to fire. The classification uses Euroclasses: A1, A2, B, C, D, E, and F, where A1 represents no contribution to fire at any stage, including a fully developed fire. A1 products do not flash over, do not produce flaming droplets, and release negligible heat and smoke when exposed to a standard fire. The test regime for A1 classification includes the ISO 1182 non-combustibility test (furnace at 750 degrees Celsius, 30 minutes) and the ISO 1716 bomb calorimeter test to measure gross heat of combustion. An A1 material must have a gross calorific potential (PCS) below 2.0 megajoules per kilogram. Calcium silicate boards meet this requirement easily, with PCS values typically below 0.5 megajoules per kilogram because the material is entirely inorganic except for the small cellulose fiber content, which burns off at a few hundred degrees Celsius without contributing meaningfully to fire growth.

A2 classification, by comparison, permits a very limited contribution to fire. Products achieving A2-s1,d0 (the best A2 subclass) may have a slightly higher organic content and may produce small amounts of smoke. The difference between A1 and A2 matters in practice for applications where absolute non-combustibility is specified, such as escape route enclosures, lift shafts, and certain high-rise facade systems. Fire resistance, as distinct from reaction to fire, is measured by EN 1363 (standard fire resistance test) or ASTM E119 in the United States. A fire resistance rating of EI 120 means that the assembly maintained integrity (E, no passage of flames or hot gases) and insulation (I, temperature rise on the unexposed face below 140 degrees Celsius average and 180 degrees Celsius at any point) for 120 minutes. Common fire resistance periods are 30, 60, 90, 120, and 180 minutes. The insulation criterion is where calcium silicate excels: its low thermal conductivity means that a relatively thin board can keep the unexposed face cool for extended periods.

Engineers specifying fire protection must check both the reaction-to-fire class and the fire resistance duration. A material with A1 classification but insufficient thickness to achieve the required EI period will fail the system test. Conversely, a thick mineral wool board that achieves EI 120 but only carries an A2 classification may not meet project requirements where A1 is mandated. Calcium silicate boards satisfy both criteria simultaneously, simplifying the specification process.

2. GF-1100 Super Calcium Silicate Fireproof Board

The GF-1100 is Mingfa’s dedicated fireproof product, distinct from the LG-Standard and LG-High Temperature series used in process insulation. The GF-1100 is formulated at 350 to 450 kilograms per cubic meter density, which strikes a balance between low enough thermal conductivity for fire insulation performance and high enough mechanical strength for handling and assembly. Thermal conductivity at 200 degrees Celsius mean temperature is approximately 0.09 watts per meter-Kelvin. Compressive strength exceeds 2 megapascals, allowing the board to serve as a structural core in door assemblies and as rigid sheathing in wall systems. Flexural strength exceeds 1.5 megapascals per ASTM C203.

The board composition is 100 percent asbestos-free. The primary crystalline phase is xonotlite (6CaO·6SiO₂·H₂O), produced through the autoclave hydrothermal process described in detail in our technical guide to calcium silicate insulation. During fire exposure, the chemically bound water in the xonotlite structure is released endothermically: the dehydration reaction absorbs heat energy, cooling the hot face and delaying the temperature rise through the board thickness. This endothermic effect is an inherent feature of hydrated calcium silicate chemistry and requires no additives or treatments. The board does not shrink, crack, or spall under standard fire test conditions. After the fire test, the dehydrated board retains its shape and position, continuing to provide a barrier even though its mechanical strength is reduced.

Standard dimensions for GF-1100 are 1200 by 600 millimeters, with thickness from 20 millimeters to 60 millimeters in 5-millimeter increments. Other sizes up to 2440 by 1220 millimeters can be produced. The boards are sanded on both faces for thickness uniformity and adhesive compatibility. Surface finish is smooth and white, suitable for direct painting or lamination with decorative facings in visible applications. Each production batch is tested for density, moisture content, flexural strength, and non-combustibility per internal quality standards aligned with EN 13501-1 requirements. Third-party fire resistance test reports are available for specific assembly configurations upon request. For full specifications, refer to the GF-1100 product page and the technical data sheets.

3. Fireproof Door Core Applications

One of the largest-volume applications for calcium silicate fireproof board is as the core material in fire-rated door assemblies. A fire door must meet both integrity (E) and insulation (I) criteria while withstanding the mechanical stresses of normal door operation: repeated opening and closing, latch impact, and potential abuse from trolleys and foot traffic. The door core must be rigid enough to support hinges and hardware, dense enough to provide screw-holding strength, and thermally insulating enough to meet the EI rating with a practical total door thickness. Calcium silicate board solves all three requirements in a single material.

A typical steel fire door rated EI 120 (120 minutes) uses a GF-1100 core of 40 to 50 millimeters thickness, sandwiched between two steel face sheets of 0.8 to 1.2 millimeters gauge. The steel faces provide the impact resistance and the calcium silicate core provides the insulation. This construction is specified in Chinese national standard GB 12955 (Fire Resistant Doors) and can be tested to EN 1634-1 for the European market. Door manufacturers in Asia, the Middle East, and Europe who use Mingfa GF-1100 cores report achieving 120-minute and in some configurations 180-minute ratings. The board is cut to the door blank dimensions by the door manufacturer; standard carbide-tipped circular saws are adequate. The core is then adhesively bonded or mechanically fastened to the steel skins depending on the door design.

Board density in fire door cores is typically specified at 400 to 450 kilograms per cubic meter. Lower densities reduce door weight but may compromise screw-holding strength for hinges and closers. Higher densities improve hardware mounting but add weight that increases hinge wear and makes the door harder to operate. Many door manufacturers specify 420 to 430 kilograms per cubic meter as the practical optimum. A 1200-by-2400-millimeter door with a 45-millimeter core at 430 kilograms per cubic meter weighs approximately 56 kilograms including the steel skins, which is within the acceptable range for a two-hinge commercial door installation.

4. Structural Steel Fire Protection

Unprotected structural steel loses approximately half its yield strength at 550 degrees Celsius and fails rapidly above 600 degrees Celsius. Building codes therefore require structural steel to maintain its load-bearing capacity for a specified fire resistance period, typically 60, 90, or 120 minutes depending on building height, occupancy type, and whether sprinklers are installed. Calcium silicate board provides this protection through board encasement: boards are mechanically fixed around the steel section to form a box that insulates the steel from fire heat.

The thickness required depends on the section factor (A/V ratio, or heated perimeter divided by cross-sectional area) and the target fire rating. For an I-section column with a section factor of 150 per meter, a 30-millimeter GF-1100 board typically achieves a 60-minute rating. Increasing the thickness to 50 millimeters raises the rating to 120 minutes. For sections with lower section factors (heavier, stockier sections that heat up more slowly), thinner boards may be adequate. These thicknesses are specified by the board manufacturer based on fire test data from accredited laboratories; engineers should not extrapolate from generic material properties alone, since the board-to-board joints, fastener type, and fixing detail all affect the system performance.

Board encasement has several practical advantages over the two alternative methods of structural steel protection. Intumescent coatings are thinner and aesthetically more flexible, but they must be applied under controlled shop or site conditions (temperature and humidity limits), require dry film thickness verification on every member, and can be damaged by impact during construction and service. Their fire performance relies on a chemical reaction that expands the coating into a char layer; if the coating is not applied at the correct thickness, is exposed to moisture before curing, or is physically damaged, the steel may reach failure temperature substantially earlier than designed. Sprayed cementitious or mineral fiber coatings are cheaper per square meter but are messy to apply, add significant dead load, and produce an uneven surface that is unsuitable for visible architectural steel. Board encasement, by contrast, provides a clean, factory-controlled box profile with consistent thickness, no curing time, no weather sensitivity during installation, and a surface that can be painted or left as-is depending on the architectural requirement. The boards are fixed with stainless steel screws into pre-installed metal framing channels, or directly to the steel using self-drilling screws where the board thickness permits.

5. Fire Compartmentation: Walls, Ceilings, and Ducts

Beyond doors and steel columns, calcium silicate fireproof board serves in passive fire compartmentation systems that divide a building into fire-resisting zones. These include fire-rated partition walls, cable tray and busbar fire barriers, ventilation and smoke extraction duct fire protection, and ceiling membrane systems. In each case the board functions as a rigid, non-combustible barrier that prevents fire spread through concealed spaces, service penetrations, or ventilation pathways.

A fire-rated partition wall using GF-1100 typically consists of a steel stud framework with calcium silicate boards screwed to both sides. A single-layer 25-millimeter board on each side of a 75-millimeter stud cavity, with mineral wool in the cavity, achieves EI 60. Double-layer construction with 25-millimeter boards on each side (50 millimeters total per face) achieves EI 120. The boards are fixed at 200-millimeter centers along the perimeter and 300-millimeter centers on intermediate studs using self-drilling drywall screws. Joints between boards are staggered between layers and filled with fire-rated joint compound or covered with intumescent joint tape. For cable tray fire barriers, the boards are cut to fit around the tray profile and supported on a separate steel framework independent of the cable tray supports. The detail at the tray penetration requires intumescent sealant to close the annular gap, which expands when heated to maintain the seal as cables degrade and collapse.

Ventilation duct fire protection is a particularly demanding application because the duct carries hot fire gases that heat the duct walls from the inside. A steel duct wrapped with 40 to 50 millimeters of calcium silicate board can maintain its cross-sectional integrity for 120 minutes under internal fire exposure, preventing fire spread from compartment to compartment through the ductwork. The boards are attached with stainless steel banding at 300-millimeter spacing, with edges butted tightly and joints sealed. Penetration details where the duct passes through fire-rated walls require coordination between the duct insulation system and the wall penetration seal, typically using a combination of the board wrap system and intumescent fire collars or pillows at the penetration.

6. Installation Standards and Quality Assurance

Correct installation determines whether a fire protection system performs as tested. The standards governing installation are EN 1366 (fire resistance tests for service installations) and ASTM E119 (standard test methods for fire tests of building construction and materials) for North American projects. On installation sites, calcium silicate boards can be cut to size using a circular saw with a carbide-tipped blade, a jigsaw, or a hand saw. Dust extraction is recommended during cutting. Drilling for fastener holes is done with standard high-speed steel bits. The boards do not require pre-drilling for self-drilling screws up to 4.8 millimeters diameter.

Mechanical fixing uses stainless steel fasteners to avoid corrosion that could compromise the fixing over the building’s service life. Grade 304 (A2) stainless steel is adequate for most interior applications. Grade 316 (A4) should be used in coastal environments, swimming pool buildings, or industrial atmospheres with chloride exposure. Screw length must provide at least 25 millimeters of embedment into the steel substrate, or 10 millimeters of protrusion through the framing member for through-fixing. Screws are spaced at 200-millimeter centers maximum around the board perimeter and at 300-millimeter centers in the field. Each board should have a minimum of two fixings in each direction unless the tested assembly specifies otherwise.

Quality assurance during installation should verify board thickness against the specification, check fastener type and spacing, confirm that board joints are tight (maximum 2-millimeter gap unless filled with approved sealant), and document each installed area with photographs before covering. Penetration seals around pipes, ducts, and cable trays require particular attention because these are the most common failure points in fire resistance tests and real fires. Each penetration should be checked against the tested detail drawing, and the installer should verify that the sealant bead dimensions and the annular gap width match the test report. Independent inspection by a certified fire protection inspector is recommended for critical applications such as high-rise residential, hospitals, and data centers. The National Fire Protection Association (NFPA) and the Institution of Fire Engineers provide guidance on inspection protocols.

Sources and Further Reading

• EN 13501-1:2018 — Fire classification of construction products and building elements. Classification using data from reaction to fire tests.
• EN 1363-1:2020 — Fire resistance tests. General requirements.
• EN 1366 — Fire resistance tests for service installations (Parts 1-13).
• EN 1634-1:2014 — Fire resistance and smoke control tests for door and shutter assemblies, openable windows and elements of building hardware.
• ASTM E119-22 — Standard Test Methods for Fire Tests of Building Construction and Materials.
• GB 12955-2008 — Fire Resistant Doors (Chinese National Standard).
• ISO 1182:2020 — Reaction to fire tests for products. Non-combustibility test.
• GF-1100 Super Calcium Silicate Fireproof Board — Product Page
• Mingfa Fireproof Door Core Board — Product Page
• Installation guidance — Technical Installation Guides