FR Core vs A2 Core ACP Panels: Which Fire Rating Does Your Ontario Project Need?

Not all aluminum composite panels are the same — and nowhere does that matter more than fire rating. Specify the wrong core for your building type and you won't pass the Ontario Building Code. Specify A2 when FR would have done the job, and you've added unnecessary cost to the facade. This guide breaks down what FR core and A2 core actually mean, what the OBC requires at each building height, and how to make the right call for your project.

Why the core material determines everything

An aluminum composite panel is a sandwich: two thin aluminum skins bonded to a core material in the middle. The aluminum skins themselves don't burn. What determines how a panel performs in a fire is entirely what's inside that core — and there are three fundamentally different options.

Standard polyethylene (PE) core burns readily. Fire-retardant (FR) core slows combustion significantly. A2 mineral core is classified as non-combustible under Canadian and international standards. These are not minor differences in performance — they place a panel in completely different regulatory categories under the Ontario Building Code, with direct consequences for which building types each can legally be used on.

The reason this matters so much in Ontario is that the province has been progressively tightening combustibility requirements for exterior cladding since several high-profile facade fires in Europe and the UK demonstrated exactly what happens when the wrong core ends up on the wrong building. If you're working on any project over three storeys in the GTA, understanding the FR vs A2 distinction is not optional — it's part of basic due diligence on the facade specification.

The three ACP cores: PE, FR, and A2

Before going deeper into FR and A2, it helps to see where each core sits in the full picture:

FR core — the commercial standard in Ontario

FR core panels are the most widely used fire-rated aluminum composite panels in Ontario. The core is composed of polyethylene blended with approximately 70% mineral fire-retardant additives — typically magnesium hydroxide or aluminium trihydrate. When exposed to heat, these minerals release water vapour, which absorbs heat and suppresses combustion.

The result is a panel that self-limits flame spread. Unlike a PE core panel, which will sustain and spread a flame once ignited, an FR core panel slows combustion dramatically and is unlikely to propagate fire across the facade surface. This behaviour is what enables FR core panels to pass CAN/ULC-S134 — the full-scale exterior wall assembly fire test required under the Ontario Building Code for cladding on Part 3 buildings.

What FR core panels are suited for

In the GTA, FR core is the default specification for the majority of commercial facade projects: retail strip plazas, mixed-use low-rise and mid-rise buildings, drive-throughs, medical offices, schools under six storeys, and commercial buildings in the 3–6 storey range. If your project falls under Part 3 of the OBC and does not specifically require a non-combustible exterior cladding assembly, FR core is almost certainly the right call.

FR core panels offer the same fabrication flexibility as standard PE core — they can be routed, folded, and formed into returns, reveals, and three-dimensional elements with no meaningful change in the fabrication process. For contractors and developers, this means the cost premium over PE core is the only real trade-off.

A2 mineral core — non-combustible, for high-rise and institutional

A2 mineral core panels represent a fundamentally different category of fire performance. The core is composed of over 90% non-combustible mineral material — primarily inorganic compounds — with only trace amounts of polymer binder. At this composition, the panel qualifies as non-combustible under CAN/ULC-S114, the Canadian standard for non-combustibility testing.

This classification matters because Ontario's Building Code, for certain building types and heights, does not simply require reduced flame spread — it requires non-combustible construction. On those projects, FR core is not an option regardless of how it performs in a fire test. The code specifies non-combustible, and only A2 (or solid aluminum plate) meets that threshold for exterior cladding.

In practice, A2 core is specified on high-rise buildings, hospitals, long-term care facilities, post-secondary institutions, correctional facilities, and other occupancy types where the OBC demands the highest level of fire resistance from the building envelope. It is also increasingly specified by architects and owners on mid-rise projects where they want the additional safety margin beyond FR core — particularly on projects where the original designer or insurer is setting a higher standard than the code minimum.

Trade-offs with A2 core

A2 core panels are heavier than both PE and FR core — the high mineral content adds weight per square metre. They are also slightly less flexible in fabrication: very tight radius folds and complex three-dimensional returns are more difficult to achieve cleanly in A2 core than in FR core. On straightforward flat and single-angle panel work, this difference is negligible. On projects with complex curved soffit or canopy elements, it may affect how certain details are fabricated.

The cost premium for A2 over FR is typically in the range of 20–30%, on top of the premium FR already commands over PE. For a large commercial facade, this difference adds up — which is why specifying A2 on a project that only requires FR is worth avoiding, and why understanding the OBC requirements precisely matters before locking in a specification.

What the Ontario Building Code actually requires

The Ontario Building Code governs exterior cladding fire requirements primarily through two pathways: building height and occupancy classification. The key threshold that applies to most commercial projects in the GTA is 18 metres — roughly six storeys in building height.

Under 18 metres (approximately 1–5 storeys)

For buildings under 18 metres, the OBC may permit combustible exterior cladding assemblies where the building is sprinklered throughout and the wall assembly passes CAN/ULC-S134 fire testing. In practice, this is where FR core panels are most commonly specified — they pass the assembly test and meet code without the added cost of A2. Standard PE core panels may technically be permitted in some low-rise configurations with appropriate fire stops, but most designers and contractors in the GTA have moved away from PE core on any commercial project given the liability risk and the modest cost difference between PE and FR.

Over 18 metres (approximately 6+ storeys)

Once a building exceeds 18 metres in building height, the OBC requires that the exterior wall assembly be non-combustible, or that it be tested and proven to resist fire spread under CAN/ULC-S134. FR core panels can satisfy this requirement when they are part of a tested assembly — but this requires that the specific panel, subframe, insulation, and substrate combination has been tested together. Using a tested assembly specification is the most common approach for mid-rise commercial projects in the 6–10 storey range.

High-rise and institutional buildings

For high-rise buildings and certain institutional occupancies — hospitals, long-term care facilities, post-secondary institutions, and similar — the OBC requires non-combustible construction for the building envelope. On these projects, A2 core is not just a better option, it is the required option for an ACP or ACM facade. The non-combustibility test standard is CAN/ULC-S114, and A2 core panels from major manufacturers are tested and certified to this standard.

It's worth noting that the OBC is not the only document in play. Many GTA municipalities and project-specific requirements — including insurer mandates and owner specifications — set higher standards than the OBC minimum. Architects and engineers of record may specify A2 on a 5-storey building simply because they prefer the additional safety margin. Always confirm the fire rating specification against the project's full design criteria, not just the building code threshold.

FR vs A2: a direct comparison

For developers, general contractors, and architects making a specification decision, here is how FR and A2 core stack up across the factors that matter most on a commercial project:

Factor	FR Core	A2 Mineral Core
Fire classification	Fire-retardant (limited combustibility)	Non-combustible (CAN/ULC-S114)
OBC compliance	Mid-rise commercial, sprinklered buildings under 18m, tested assemblies	High-rise, institutional, non-combustible construction requirements
Fire test standard	CAN/ULC-S134 (full-scale assembly test)	CAN/ULC-S114 (non-combustibility) + CAN/ULC-S134
Mineral core content	~70% mineral fill	90%+ mineral fill
Weight	Moderate — heavier than PE, lighter than A2	Heavier — adds load to subframe design
Fabrication flexibility	Same as PE core — routes, folds, forms normally	Slightly reduced — tight radius folds more difficult
Cost vs PE core	+20–30%	+40–60%
Availability (GTA)	Wide — most major ACP suppliers stock FR core	Available — may require longer lead time on custom colours
Typical projects	Retail, medical, commercial mid-rise, mixed-use	High-rise, hospitals, schools, LTC, government

How to specify the right core for your project

The right core for any given project comes down to three things: building height, occupancy type, and the project's design criteria. Here is the decision path most GTA contractors and developers follow:

Step 1 — Confirm the building height and occupancy classification. Is the building subject to Part 3 of the OBC? What is the building height in metres? What is the occupancy — commercial, residential, institutional? These answers determine which OBC articles govern the exterior wall assembly.

Step 2 — Review the project specifications. The architect or engineer of record will typically specify the core type in the Division 7 or Division 9 specifications, or in the product data sheets attached to the drawings. If FR core is specified and the building height and occupancy support it, that's your answer. If A2 is specified on a project where FR would technically comply, ask whether the upgrade is driven by insurer requirements, owner preference, or code — the answer affects whether it's negotiable.

Step 3 — Confirm the tested assembly. Specifying a core type is not enough on its own. The entire wall assembly — panel, adhesive, subframe, insulation, and substrate — must be part of a system that has been tested to CAN/ULC-S134 or CAN/ULC-S114 as applicable. Pure Fabrication works with panel manufacturers whose systems carry current test reports, and we can confirm assembly compliance as part of the shop drawing process.

Step 4 — Get the right panels sourced early. A2 core panels in certain colours and profiles can take 2–4 weeks longer to source than standard FR core panels. If your project requires A2, flag it early so material procurement doesn't become a schedule risk. Our team handles panel sourcing directly — we can lock in material and confirm lead times as soon as the core type is confirmed on the drawings.

If you're not sure which fire rating your project requires, or if the specification hasn't been set yet, reach out to us early. We work alongside architects, engineers, and GCs at the specification stage regularly — helping confirm what the OBC requires for a specific building type before the project goes to tender is part of what we do. It's easier to get the specification right the first time than to re-specify mid-tender because the submitted panel doesn't meet code.

Both FR and A2 core panels, when properly specified and installed as part of a compliant rainscreen facade system, will perform reliably for the 30–40 year lifespan typical of a well-maintained ACP facade in Ontario. The core type affects fire performance and code compliance — it doesn't change the material's weather resistance, colour stability, or long-term durability on the exterior.