ACP Reference Library · Core Types · Materials

ACP Core Types Explained: PE, FR, A2 and A1 Aluminium Composite Panels

ACP core type is the most important hidden part of an aluminium composite panel. The outside of two panels may look identical, but the core inside can completely change the panel’s fire behaviour, weight, rigidity, fabrication, approval status, and suitability for facade use.

This guide explains the main ACP core types: PE core, FR core, A2 core, and A1-direction aluminium composite panels. It also explains why core percentage, mineral loading, fire classification, test reports, and complete facade system testing matter more than marketing names.

ACP core types in one minute

PE core ACP is polymer-rich, lightweight, easy to fabricate, and combustible. FR core ACP contains mineral fillers to reduce combustibility compared with PE. A2 core ACP contains very high mineral content and targets stronger reaction-to-fire classification. A1-direction ACP pushes the technology further toward non-combustible performance with very low organic contribution. Combustibility is a material property; the real risk occurs when a core type is selected for an unsuitable application. The correct core must be selected according to building use, height, local fire code, test evidence, authority acceptance and complete facade system design.

Evolution of aluminium composite panel ACP core types showing polyethylene PE core, fire-retardant FR core, A2 high mineral core and A1 direction core technology for fire safety selection — ACP core evolution should be understood as a material selection and application suitability question, not as a product name or colour selection exercise.

Important selection principle

Combustible materials exist in many parts of the built environment. The issue is not the existence of a combustible material by itself; the issue is whether that material is selected, specified, approved and installed in an application where its fire behaviour is suitable and permitted. ACP core selection is therefore a stakeholder responsibility involving the developer, consultant, contractor, fabricator, supplier, authority and installer.

Definition

The hidden centre of ACP

What is the core of an ACP?

The core of an ACP is the central layer between the front and rear aluminium skins. It gives the panel thickness, contributes to rigidity, affects weight, influences fabrication behaviour, and strongly controls fire performance.

In simple terms, the aluminium skins give the panel its metal surface, while the core decides much of the internal behaviour. This is why ACP should never be judged only by colour, coating, or total thickness.

Simple definition

ACP core type means the material formulation inside the aluminium composite panel, such as PE, FR, A2, or A1-direction core technology.

For full layer explanation, read ACP Anatomy Explained.

Overview

Four main core directions

Main types of ACP core

PE Core

Polyethylene core

Lightweight, economical, easy to fabricate, but combustible and restricted in many facade applications.

FR Core

Fire-retardant core

Mineral-filled core designed to reduce combustibility and improve fire behaviour compared with PE core.

A2 Core

High mineral core

Higher fire-performance direction using very high mineral content and limited organic binder.

A1 Direction

Non-combustible ambition

Advanced core technology direction targeting very low combustibility and A1 classification where independently proven.

Comparison Table

PE vs FR vs A2 vs A1 direction

ACP core types comparison

Core type	Typical composition direction	Fire behaviour direction	Common use caution
PE Core ACP	Polyethylene-rich core	Combustible	Generally not suitable for regulated high-rise facade applications.
FR Core ACP	Polymer binder with mineral filler	Improved fire behaviour compared with PE	Actual performance depends on mineral content, formulation, and testing.
A2 Core ACP	Very high mineral content with limited binder	High reaction-to-fire performance direction	Must be verified by valid A2 classification and project acceptance.
A1 Direction ACP	Highly mineral or non-combustible direction with very low organic contribution	Advanced non-combustible performance direction	Requires strong independent testing, manufacturing control, and clear field of application.

Core type must be selected with ACP Fire Safety, NFPA 285, and local regulation in mind.

PE Core

Polyethylene core ACP

PE core ACP explained

PE core ACP uses a polyethylene-rich core between aluminium skins. It helped ACP become popular because it is lightweight, economical, easy to fabricate, and suitable for many signage, interior, and low-risk applications.

The major limitation is fire behaviour. PE core is combustible and can contribute fuel in fire. For this reason, PE core ACP is restricted, prohibited, or unsuitable for many regulated exterior facade applications, especially high-rise cladding.

PE core ACP is commonly considered for

Interior decorative panels where code permits
Signage and display boards
Temporary exhibition work
Low-risk applications subject to local regulation

PE core caution

PE core ACP can be suitable for permitted low-risk uses such as signage or interiors where allowed, but it should not be selected for regulated facade use without checking local fire code, building height, occupancy, authority requirements, and complete wall system safety.

FR Core

Fire-retardant core ACP

FR core ACP explained

FR core ACP contains mineral fillers and fire-retardant components designed to reduce combustibility compared with PE core. It represents an important step in ACP evolution because it moves the panel away from purely polymer-rich core behaviour.

However, FR is not one fixed universal formula. Different manufacturers may use different mineral percentages, binders, additives, and processing methods. Therefore, FR core ACP must be judged by valid fire classification, test reports, certification, and production consistency.

FR core ACP must verify

Actual mineral content direction
Reaction-to-fire classification
Smoke and flaming droplet classification where applicable
Product thickness and aluminium skin thickness
Test laboratory and report number
Authority acceptance for the intended building use

A2 Core

High mineral fire performance

A2 core ACP explained

A2 core ACP is a higher fire-performance aluminium composite panel direction. It normally uses very high mineral content with limited organic binder, aiming to achieve A2 reaction-to-fire classification under relevant standards.

A2 core technology is more difficult to manufacture than PE core because high mineral loading affects compounding, extrusion, bonding, flexibility, weight, routing, and folding behaviour. This is why A2 ACP requires stronger process control and proper test evidence.

A2 ACP advantages

Stronger fire-performance direction than PE and many standard FR cores
Useful for regulated facade applications where accepted by code
Lower combustible contribution compared with polymer-rich cores
Better alignment with modern cladding safety expectations

A2 ACP caution

A2 classification must be proven by valid test reports. Do not accept “A2 type” or “A2 grade” marketing language without independent classification evidence and project-specific acceptance.

A1 Direction

Advanced non-combustible core direction

A1-direction ACP explained

A1-direction ACP is the advanced edge of aluminium composite panel core technology. It aims toward non-combustible performance by using highly mineral or non-combustible core systems with very low organic contribution.

A1-direction ACP is technically challenging because the product must balance fire performance, bonding, lamination, panel flatness, fabrication behaviour, weight, and long-term durability. The more mineral and less organic binder inside the core, the more important manufacturing discipline becomes.

A1-direction ACP must prove

Independent A1 classification where claimed
Calorific value and combustibility evidence where required
Production repeatability and batch traceability
Peel strength and bonding performance
Fabrication instructions and limitations
Facade system suitability and local approval

A1-direction ACP should not be treated as a slogan. It must be treated as a tested, documented, and controlled technology.

Fire Classification

Do not rely on names only

Core name versus fire classification

Core names such as PE, FR, A2, and A1-direction are useful, but fire classification must come from testing. A product should not be approved only because the name sounds safe. The test report must identify the exact panel, core, thickness, aluminium skin, standard, laboratory, and result.

Claim	What to ask	Why it matters
FR ACP	Which fire classification and which test report?	FR is not a universal fixed performance level.
A2 ACP	Is there a valid A2-s1,d0 or applicable classification report?	A2 must be proven by testing, not claimed by name.
A1 ACP	Which independent lab classified it as A1 and under which standard?	A1 is a very strict claim and needs strong evidence.
NFPA 285 compliant	Which complete wall assembly was tested?	NFPA 285 is an assembly test, not a panel-only label.

Read Fire Testing Standards for test comparison.

Weight and Fabrication

Core affects more than fire

How core type affects weight and fabrication

Core type affects more than fire safety. It also affects weight, cutting, routing, folding, bending, cassette returns, drilling, handling, and installation. Higher mineral cores are usually heavier and may require more careful fabrication than PE core panels.

Core type	Weight direction	Fabrication behaviour
PE Core ACP	Usually lighter	Easy to route, fold, and bend.
FR Core ACP	Moderate to heavier than PE	Depends on mineral loading and formulation.
A2 Core ACP	Usually heavier	Requires careful routing, folding, and handling.
A1 Direction ACP	Often heavier advanced direction	Requires manufacturer-specific fabrication guidance.

Read ACP Weight Guide and ACP Thickness Guide.

Application Selection

Which core for which use?

ACP core type selection by application

Application	Core selection direction	Important approval point
Interior decoration	PE, FR, or higher grades depending on code and occupancy.	Check internal fire requirements and smoke limitations.
Signage	PE or FR commonly used depending on location and exposure.	Outdoor signs must consider wind, weather, and local fire rules.
Low-rise facade	FR, A2, or A1-direction depending on local code and project risk.	Do not assume low-rise means no fire requirement.
High-rise facade	A2 or A1-direction commonly preferred where regulation is strict.	Full system testing and authority approval may be required.
Canopy and soffit	FR, A2, or A1-direction depending on location and fire exposure risk.	Overhead applications require careful fixing and fire review.

For use cases, read ACP Applications.

Procurement

How to verify core type

ACP core type procurement checklist

Buyers and consultants should not approve ACP core type based only on brochure wording. The core must be verified through test documents, technical data, production traceability, and project-specific compliance.

Request these details

Declared core type: PE, FR, A2, or A1-direction
Product technical data sheet
Reaction-to-fire classification report
Calorific value or combustibility data where required
Smoke and flaming droplet classification where applicable
Full facade system test report where required
Aluminium skin thickness and total panel thickness
Panel weight per square metre
Peel strength and bonding data
Batch traceability and certification documents

For buyer guidance, read ACP Procurement Guide.

Common Mistakes

Core type misconceptions

Common mistakes about ACP core types

Mistake 1

Thinking all FR cores are equal

FR performance varies by mineral content, binder, formulation, manufacturing, and test classification.

Mistake 2

Treating A2 as only a label

A2 must be proven by valid reaction-to-fire classification, not only marketing wording.

Mistake 3

Ignoring system testing

A strong core does not remove the need for facade assembly testing where required by code.

Mistake 4

Comparing only price

Cheaper cores may not meet fire, weight, bonding, or long-term facade requirements.

Final Principle

Core is not cosmetic

The correct way to choose ACP core type

ACP core type should be selected according to building use, height, facade system, local code, fire testing, authority approval, coating requirement, fabrication method, and long-term performance need. The purpose of core classification is not to blame earlier technologies, but to ensure each material is used only where it is suitable, compliant and supported by evidence.

Final rule

Do not select ACP core type by colour, price, sample appearance, or verbal claim. Select it by tested classification, core composition, project regulation, complete facade assembly, and responsible documentation.

FAQ

Quick answers

Frequently asked questions

What are the main ACP core types?

The main ACP core types are PE core, FR core, A2 core, and A1-direction core technology. Each has different fire behaviour, weight, fabrication, and application suitability.

What is PE core ACP?

PE core ACP uses a polyethylene-rich core. It is lightweight and easy to fabricate, but combustible and restricted in many facade applications.

What is FR core ACP?

FR core ACP contains mineral fillers and fire-retardant components designed to improve fire behaviour compared with PE core ACP.

What is A2 core ACP?

A2 core ACP uses very high mineral content and limited organic binder to achieve stronger reaction-to-fire performance under relevant classification standards.

What is A1 ACP?

A1 ACP refers to an advanced non-combustible direction of aluminium composite panel technology where the product aims for A1 classification through very low combustible contribution and independent testing.

Is FR ACP non-combustible?

Not automatically. FR means fire-retardant, not necessarily non-combustible. The actual fire performance must be verified through valid test reports.

Is A2 ACP better than FR ACP?

A2 ACP generally represents a stronger fire-performance direction than standard FR ACP, but the actual product must be verified by classification reports and project approval.

Can core type affect ACP weight?

Yes. PE core ACP is usually lighter, while FR, A2, and A1-direction cores are usually heavier because of higher mineral content.

Does core type affect fabrication?

Yes. Higher mineral cores can be heavier and may require more careful routing, folding, cutting, and handling than PE core panels.

Which ACP core should be used for high-rise facades?

High-rise facades usually require fire-rated core technologies such as A2 or A1-direction systems depending on local code, authority approval, and complete facade system testing.

Related technical guides

Fire Safety

ACP Fire Safety Guide

Understand fire classification, core risk, system testing, and facade safety.

Open

Testing

Fire Testing Standards

Compare reaction-to-fire, combustibility, and full facade assembly tests.

Open

Weight

ACP Weight Guide

Learn how PE, FR, A2, and A1-direction cores affect ACP weight.

Open

Procurement

ACP Procurement Guide

Know what documents to verify before specifying or buying ACP.

Open