Is GRC Fire Rating Class A? Fire Acceptance Basis and Engineering Compliance Explained

Fire rating is the silent gatekeeper of every GRC project in China. Get the documentation wrong and the project stalls at the fire inspection (fire acceptance inspection) — sometimes for months, sometimes permanently. The good news: GRC is unambiguously Class A1 (A-grade non-combustible) under GB 8624-2012, the Chinese national standard for building material fire classification. The bad news: "Class A" on paper and "Class A acceptance" in practice are not the same thing, and the documentation chain has to hold together. This article unpacks the technical basis, the regulatory framework, and the practical documentation that fire inspectors actually want to see.

The Regulatory Framework: GB 8624-2012 and the A1/A2 Distinction

GB 8624-2012 (Classification of Burning Behaviour of Building Materials and Products) is the Chinese equivalent of the European EN 13501-1 standard. Under this standard, non-combustible materials are classified as A1 (no combustible content at all) or A2 (limited combustible content, with a gross calorific value below a defined threshold). Both A1 and A2 are accepted as "Class A non-combustible" (Class A non-combustible materials) for fire design purposes in Chinese building codes.

GRC, being an inorganic composite of cement, quartz sand, alkali-resistant glass fibre, and water — with no polymer binder, no plasticiser, no organic content — sits squarely in the A1 category. There is no combustible fraction in any standard GRC formulation.

Note: GRG (gypsum-based) is also A1 under GB 8624, but for different reasons — gypsum is chemically bound water and does not support combustion. GRP (fibreglass-reinforced plastic) is not A1 — the polyester or epoxy resin is combustible, and GRP typically rates B1 or below.

What the Fire Test Actually Measures

For a material to be classified A1 under GB 8624-2012, three test results are required:

1. Non-combustibility test (GB/T 5464): the material sample is exposed to 750°C in a furnace. Average temperature rise must be ≤30°C, and no sustained flaming.
2. Gross calorific value (GB/T 14402): the material's PCS value must be ≤2.0 MJ/kg to qualify for A1.
3. Smoke and toxic gas emission: A1 materials are exempt from the smoke and toxicity tests, because the underlying chemistry guarantees no smoke or toxic gas generation in a fire.

For GRC, all three are easily met. The fibre (alkali-resistant glass fibre) is non-combustible. The cement matrix is non-combustible. The quartz sand aggregate is non-combustible. The total calorific value of a standard GRC formulation is well below 1 MJ/kg, often below 0.5 MJ/kg.

Why Some GRC Components Get Flagged at Fire Inspection Anyway

Despite GRC being unambiguously A1, fire inspectors sometimes flag GRC components in practice. The reasons are almost always documentation gaps, not material failures:

• Missing or expired type test report: the GRC factory's A1 type test report must be issued by a CNAS-accredited lab (China National Accreditation Service for Conformity Assessment) and must be within its validity period (typically 4 years for a GB 8624 test).
• Surface coating not tested separately: if the GRC component has a topcoat (fluorocarbon paint, silicone sealant, anti-graffiti coating), the coating must have its own GB 8624 test report. A coating rated B1 or below can drag the entire assembly below A1, even if the substrate is A1.
• Composite with other materials: when GRC is bonded to insulation (XPS, PIR, rock wool), or mounted on aluminium framing, the assembly as a whole must be fire-rated, not just the GRC layer. Some insulation materials are not A1, and the inspector will flag the assembly.
• Documentation chain: the factory certificate, batch test report, on-site material entry record, and concealed-work inspection record must all be consistent. A break in the chain (e.g., a missing on-site entry signature) is enough to trigger a re-inspection.

Practical Documentation Checklist for GRC Fire Acceptance

For a typical GRC façade or interior decoration project, the fire acceptance documentation set should include:

1. Material type test report: GB 8624-2012 A1 rating, issued by a CNAS-accredited lab, within validity period.
2. Factory batch test report: per-batch non-combustibility and dimensional data, signed by the factory quality officer.
3. Coating material test report: if any surface coating is applied, a separate GB 8624 test report for the coating.
4. Insulation material test report: if the GRC is part of a composite panel with insulation, fire rating for the insulation layer.
5. On-site material entry record: signed by the site supervisor and the supervision engineer at the time of material arrival.
6. Concealed-work inspection record: signed after each layer of installation (substructure, GRC panels, joints) before the next layer covers it.
7. Final acceptance test report: in some jurisdictions, a final on-site smoke and combustion test on a random panel.

Most project delays at fire inspection come from gaps in items 5–7, not from item 1. The material is fine; the paperwork chain is broken.

Common Misconceptions

Three misconceptions about GRC and fire rating are worth clearing up:

• "GRC is A-grade because it's thick." No. Fire rating is about chemistry, not thickness. A 3 mm GRC panel is A1 if the formulation is correct; a 30 mm GRP panel is B1 or below because the resin is combustible.
• "All GRC is the same in a fire." Almost — for properly formulated GRC. But "GRC-look" panels made with polymer-modified mortar or recycled aggregate substitution may have organic content above the A1 threshold. Always require the type test report.
• "A2 is the same as A1 in practice." For most Chinese building code applications, yes — both qualify as "Class A non-combustible" for fire design. But for some high-risk applications (e.g., nuclear plant auxiliary buildings, some tunnel applications), only A1 is accepted. Check the project specification.

Bottom Line

GRC is unambiguously A1 non-combustible under GB 8624-2012. The fire acceptance risk for GRC projects is not the material — it is the documentation chain and the composite assembly details. Specifying the documentation set in the contract, and verifying the factory's type test report before procurement, eliminates 95% of the fire acceptance risk.

Guangdong Qinglong Construction provides GB 8624-2012 A1 type test reports from CNAS-accredited labs for all standard GRC formulations, with full documentation support for fire acceptance. Visit the official website for sample documentation packages.