Magnesium Board Fire Rating: What Class A1 Non-combustible Really Means
Class A1 is the highest grade in GB 8624-2012: the material undergoes virtually no flaming combustion and releases negligible heat or smoke in a fire. Magnesium boards as inorganic products can reach A1 — but an A1 board is not automatically an A1 system; partition/duct fire resistance also depends on assembly and installation.
How are reaction-to-fire classes defined?
GB 8624-2012 classifies materials into A (non-combustible, incl. A1/A2), B1 (retarded), B2 (combustible) and B3 (easily flammable), determined via non-combustibility, calorific value and single-burning-item tests, reported by third-party laboratories.
Why can inorganic boards reach A1?
Magnesium boards consist mainly of magnesium cementitious materials and mineral aggregates with no combustible organic matrix and extremely low calorific value, satisfying A1 criteria in non-combustibility tests — a fundamental difference from boards based on organic binders.
Material class vs system fire resistance
Reaction-to-fire answers 'does the material burn?'; fire resistance answers 'how long does the assembly survive?' (e.g. duct 0.5h/1.0h). The latter is determined by full-system fire tests of boards plus studs and connections. Projects need both: A1 materials and system assemblies sized to designed resistance.
Cited Standards & Sources
This article is interpretive guidance; actual projects must follow design documents and current standard texts.
FAQ
How to verify a supplier's A1 claim?+
Request a GB 8624-2012 test report from a nationally accredited lab, verify product name, model/thickness and manufacturer match the delivered goods, and check the reaction-to-fire conclusion page. Batch retention samples can be retested if needed.