# 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.

## 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**.

## Frequently asked questions

### What is the actual difference between FR and A2?

It is the proportion of mineral filler in the core. An FR core is typically around 70% mineral and still contains meaningful polymer. An A2 core is roughly 90% or more mineral, which places it in EN 13501-1 class A2 — limited combustibility. A2 costs more and is heavier, but it is the grade specified where fire spread genuinely cannot be tolerated.

### Is plain PE-core ACP banned in India?

There is no blanket national ban, and PE-core panels remain widely sold. But NBC 2016 Part 4 governs fire and life safety for the building as a whole, and many state fire authorities and insurers now refuse PE core on tall or high-occupancy buildings. Treat PE as unusable on any commercial facade rather than as a cheap option.

### How do I verify what core a panel actually has?

Ask for the manufacturer's test certificate to EN 13501-1 for the specific product and thickness, not a general brochure claim, and check that the batch matches. Cut sections of a delivered panel also make the core visibly obvious — a genuine mineral core is dense and pale, not black and waxy.

## Sources

- [NBC 2016, Part 4](https://www.bis.gov.in/standards/national-building-code/?lang=en) — Fire and life safety
- [EN 13501-1](https://standards.cencenelec.eu/ords/f?p=CEN:105) — Reaction to fire classification
- [IS 6248](https://standards.bis.gov.in/website/published-standards/department-wise) — Metal cladding

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Source: https://hagerstone.com/glossary/acp-fr-b1-core