Solid Aluminium Panel — Specification and Use

A solid aluminium panel is a single sheet of aluminium alloy folded into a cassette and hung on a sub-frame, with no polymer core or bonding line. Being one non-combustible material through its thickness, it is specified over ACP where fire performance, deep folds, complex geometry or absolute flatness govern.

By Dhruv Agarwal · · 2 min read

What it is

A single sheet of aluminium alloy, folded into a cassette and hung on a sub-frame. Unlike ACP there is no polymer core and no bonding line — the panel is one material through its whole thickness.

That single fact drives most of the specification decisions around it.

Specification at a glance

PropertyTypical specification
Alloy3003, 3105 or 5005 to IS 737
Thickness2mm — 4mm for cassette cladding
FinishPVDF coil coating, or anodised
Coating standardAAMA 2605 for the highest weathering class
Fire classificationA1 / non-combustible to EN 13501-1
Panel formatCassette with folded returns, rear stiffeners as required

Why it gets specified

Fire performance is not a discussion. The panel is metal through its section, so there is no core grade to argue about, no test certificate to match against a delivered batch, and no substitution risk at supply stage. On high-rise, healthcare and high-occupancy buildings this removes the single most contested item in a facade submission.

It holds a fold. Deep returns, sharp corners, tapered panels and curved geometry are achievable in solid sheet in ways a composite panel resists, because there is no core to delaminate at a tight radius.

Flatness. On a prestige elevation viewed in raking light, a well-detailed solid aluminium cassette with rear stiffeners reads flatter than most alternatives.

What drives the cost

Sheet thickness · alloy · finish class, with PVDF and anodised costing more than polyester · panel size and the number of folds · rear stiffener extent · whether panels are flat, curved or tapered · sub-frame complexity · building height and access.

Solid aluminium typically lands above ACP and below most natural stone per square metre, but the gap narrows once ACP is specified in A2 grade.

Where projects go wrong

  • Thin sheet on a large panel. The result is oil-canning — visible waviness that no amount of site adjustment removes. It is a design error, fixed at panel-size and stiffener stage, not on site.
  • Stiffeners bonded with the wrong adhesive. A facade in Indian summer sun runs far hotter than ambient. The bond must be rated for that service temperature or stiffeners debond and the panel bellies out.
  • Assuming a non-combustible panel makes a compliant facade. It does not. Cavity barriers and insulation grade still govern.
  • Leaving the finish class unnamed. "Powder coated" spans products lasting five years and products lasting twenty-five. Name the resin class.

Standards referenced

Sheet alloy and temper under IS 737. Reaction-to-fire classification to EN 13501-1. High-performance organic coating performance to AAMA 2605.

Standards referenced

  • IS 737 — Wrought aluminium and aluminium alloy sheet and strip (Bureau of Indian Standards)
  • EN 13501-1 — Reaction to fire classification (CEN-CENELEC)
  • AAMA 2605 — High-performance organic coatings on aluminium (Fenestration and Glazing Industry Alliance)

Frequently asked

Where fire performance governs, where the panel must be folded into deep returns or complex geometry, and on prestige elevations where absolute flatness matters. Solid aluminium is a single metal sheet with no polymer core, so the core fire debate does not arise at all. It costs more per square metre than ACP and is heavier to handle, which is why ACP still dominates general areas.

Commonly 2mm to 4mm for cassette panels. Thickness is driven by panel size, wind pressure and how flat the panel must stay: a large panel in thin sheet oil-cans, showing visible waviness across the face. Stiffeners bonded to the rear let a thinner sheet span further, but they must be bonded with a structural adhesive rated for the service temperature.

The panel does, but the assembly does not. Aluminium is non-combustible as a metal, yet a ventilated cavity behind any panel still behaves like a chimney. Cavity barriers at every compartment line and non-combustible insulation remain mandatory. Specifying solid aluminium and then omitting barriers produces a facade that is still non-compliant.

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