ACP Fire Rating: What FR, B1 and A2 Actually Mean
The fire rating of an aluminium composite panel is set almost entirely by what sits between its two aluminium skins: a standard polyethylene core burns readily, an FR (fire-retardant) core is mineral-filled to resist ignition, and an A2 core is mineral enough to be classed as limited-combustibility.
By Dhruv Agarwal · · 2 min read
Why it matters on a facade project
After Grenfell, facade cladding fire performance stopped being a specification detail and became the first question asked in a fire review. The panels look identical from outside — the only thing separating a compliant facade from a dangerous one is the material hidden between the two aluminium skins.
It is also one of the easiest places on a project to be substituted without anyone noticing until a certificate is requested.
How it is specified in practice
| Core grade | Mineral content | Typical use | Relative cost |
|---|---|---|---|
| PE (polyethylene) | None | Signage, interior, low-rise non-critical | Baseline |
| FR (fire-retardant) | ~70% mineral filler | Common commercial specification | Higher |
| A2 (limited combustibility) | ~90%+ mineral | High-rise, hospitals, high-occupancy | Highest |
Beyond the panel itself, the fire performance of a facade also depends on what sits behind it — cavity barriers, the insulation grade, and how the cavity is compartmented at each floor. A compliant panel over an unstopped cavity is not a compliant facade.
Common mistakes
- Specifying "FR ACP" and stopping there. FR is a family, not a grade. Without naming the EN 13501-1 classification and requiring the test certificate for that exact product and thickness, the specification is not enforceable.
- Ignoring the cavity. A ventilated ACP facade has a continuous air gap behind it, which behaves like a chimney in a fire unless cavity barriers stop it at each compartment line.
- Accepting a brochure instead of a certificate. Brochures describe product families. Certificates describe tested assemblies. Only one of those is evidence.
- Letting the core be substituted at supply stage. The panel that arrives on site should be verifiable against the panel that was approved. Cut sections and batch traceability are the practical check.
- Assuming thicker aluminium skin improves fire performance. It does not. The skin is 0.5mm of aluminium either way; the core decides the outcome.
Standards referenced
Fire and life safety for the building follows NBC 2016, Part 4. Panel reaction-to-fire classification is expressed under EN 13501-1, which is the system the A2 / B1 grades come from. Metal cladding material requirements sit under IS 6248.
Standards referenced
- NBC 2016, Part 4 — Fire and life safety
- EN 13501-1 — Reaction to fire classification
- IS 6248 — Metal cladding