Metal Cladding Systems

Metal cladding is the family of opaque façade panels made from sheet metal — aluminium, steel, zinc, copper, stainless and their alloys — hung on a building as a rainscreen or sealed cladding. Light, strong, formable and recyclable, metal is the most versatile cladding material there is, spanning flat composite cassettes, crisp solid-metal trays, profiled and standing-seam sheet, woven mesh and perforated screens.

A material, several systems

Metal cladding is almost always installed on the rainscreen principle (covered in its own entry): an open-jointed or interlocking metal outer skin on a ventilated cavity, with the weather barrier on the back-up wall. What this entry covers is the metals themselves, the panel formats made from them, the all-important finishes — and the fire-safety lessons that have reshaped how metal composite panels are specified.

Each cladding metal brings a distinct combination of weight, strength, durability, cost and — crucially — appearance and ageing behaviour.

Aluminium

Aluminium dominates: light, corrosion-resistant, easily rolled and folded, and available pre-finished in any colour. It is the skin of composite panels and the metal of most solid cassettes, flashings and trims. It does not rust and takes durable PVDF coatings and anodising.

Steel — coated, stainless, weathering

Coil-coated (organic-coated) galvanised steel is the economical workhorse for profiled and standing-seam roofing and cladding. Stainless steel gives strength, corrosion resistance and a self-finished appearance for prestige and coastal work. Weathering steel (Corten-type) develops a stable russet patina prized for cultural and landscape buildings, needing careful run-off detailing and unsuitable for chloride-heavy coastal sites.

Zinc, copper and titanium

Zinc and copper are the classic ‘living’ metals: both weather to a stable, self-protecting patina (zinc to a soft grey, copper to brown then verdigris green) and last for many decades with no coating. They are used for standing-seam, shingle and flat-lock cladding on heritage, cultural and high-end residential buildings. Titanium and bronze occupy the premium, ultra-durable end of the palette.

The metal composite panel — two thin metal skins bonded to a lightweight core — is the most widely used flat metal cladding, valued for its flatness, light weight and ease of fabrication. It is also the product at the centre of the most important fire-safety reckoning in the cladding industry.

How a composite panel is built

An aluminium composite material (ACM, also MCM) panel is typically two 0.5 mm aluminium skins bonded to a 3 mm core, giving a rigid, dead-flat 4 mm panel that is light, easily routed-and-folded into cassettes, and available in any finish. The flatness and crispness that flat solid metal struggles to achieve are the panel’s great virtue.

The core is everything

The single most important property of a composite panel is the fire behaviour of its core. Early panels used a polyethylene (PE) core, which is combustible and, in a façade fire, melts and burns fiercely — the mechanism that drove the catastrophic spread at the Grenfell Tower fire and other façade fires. The industry has since moved decisively to fire-rated cores: mineral-filled FR cores and, for the highest requirement, limited-combustibility A2 cores classified A2-s1,d0 to EN 13501-1. Many jurisdictions now ban combustible cores in the external walls of tall and high-risk buildings outright. For any building of significance, an A2 (or better) core is now the baseline expectation, and the PE-core panel is effectively obsolete in regulated markets.

Metal cladding is fabricated into a range of formats, each with its own fixing method, joint language and appearance.

Cassettes and trays

Composite and solid-metal sheets are routed and folded (composite) or press-braked (solid) into cassette trays with returned edges, hung on the rainscreen carrier by hook-on, secret-fix or face-fix methods. Cassettes give the crisp, flat, deep-reveal modern façade and allow individual panel replacement.

Profiled and standing-seam sheet

Roll-formed trapezoidal and sinusoidal profiled sheet is the economical industrial and large-area cladding, fixed through the face or concealed. Standing-seam and interlocking-plank systems join sheets with raised, folded seams for a linear, weathertight skin used on both walls and roofs, and are the natural format for zinc, copper and coated steel.

Mesh, perforated and expanded metal

Woven metal mesh, perforated sheet and expanded metal create semi-transparent screens used for solar shading, car-park ventilation cladding, balustrade infill and decorative veils — admitting air and filtered light while giving a metallic surface. These are tensioned or framed screens rather than solid panels.

The finish determines a metal façade’s colour, durability and how it ages, and is specified with as much care as the metal itself.

Organic coatings (paint)

PVDF (polyvinylidene fluoride, e.g. Kynar/Hylar) is the premium architectural paint finish — highly durable, colour-stable and used coil-applied or post-applied on aluminium and steel, with long colour and gloss warranties. FEVE and high-durability polyesters are alternatives; standard polyester suits less demanding work. Coil-coated finishes are factory-applied to the metal before forming, giving consistent quality.

Anodising

Anodised aluminium grows a hard, integral oxide layer for a metallic, non-fading finish in natural, bronze, black and coloured tones — valued for its depth and durability, governed by the QUALANOD quality label and EN ISO 7599.

Self-finished and living surfaces

Stainless steel is supplied bead-blasted, brushed, mirror-polished, patterned or coloured; weathering steel, zinc and copper are left to develop their natural patinas. Mill-finish and pre-weathered (pre-patinated) options give the patina look from day one. The choice of finish is an architectural decision about colour, reflectivity and how the building will look as it ages.

As a rainscreen, metal cladding’s performance is delivered by the whole assembly — panel, cavity, insulation and back-up wall — rather than by the panel alone, and follows the rainscreen principles covered in that entry.

Weather and structure

Open-jointed metal rainscreens drain and ventilate behind the panels; standing-seam and sealed systems shed water at the seams. Panels and fixings resist wind pressure and suction, with safety factors against panel detachment; metal’s strength-to-weight makes large, light panels possible, but thin metal must be stiffened (by the composite core, folded returns or profiling) to stay flat under wind and to avoid visible oil-canning.

Fire, thermal and acoustic

Fire performance hinges on the panel core and the cavity barriers (see the composite-panel and rainscreen entries) — non-combustible A2 cores and properly installed cavity barriers are now the norm for tall buildings. Thermal performance comes from the continuous insulation behind the panels, with thermally broken brackets controlling the cold bridge. Metal panels add little acoustic mass, so the back-up wall does the acoustic work; perforated metal with an acoustic backing is used where sound absorption is wanted.

Oil-canning and flatness

A characteristic challenge of flat metal is oil-canning — visible waviness in the flat face caused by stresses, fixing and thermal movement. It is managed by using composite or stiffened panels, controlling panel size, adding stiffeners or a light profile, and careful fixing; it is a perception issue the specification must address for large flat metal areas.

Metal cladding is fabricated by CNC routing and folding (composite) or press-braking and roll-forming (solid and profiled), increasingly driven directly from the digital model, and installed on a rainscreen carrier system.

Movement and tolerance

Metal’s relatively high thermal expansion means panels grow and shrink noticeably, so joints, slots and fixings must accommodate movement without buckling or oil-canning; large panels and dark colours (which run hotter) need particular attention. The carrier system absorbs structural tolerance and sets the panels to a true plane with consistent joints.

Critical junctions

As with any rainscreen, the make-or-break details are the base, head, corners, movement joints and the junctions around windows and openings, where drainage, ventilation, the back-up weather line and the fire cavity-barrier line must all be maintained. Folded metal flashings and trims, fabricated from the same metal and finish, resolve these junctions.

Metal cladding is one of the most widely used façade families, appropriate from industrial sheds to landmark cultural buildings.

Composite and solid-metal cassettes clad commercial offices, retail, leisure, transport and mixed-use buildings; profiled and standing-seam sheet clads industrial, logistics, agricultural and large-area buildings and many roofs; zinc, copper and weathering steel clad cultural, civic and high-end residential projects where their patinas suit the architecture; and mesh, perforated and expanded metal form shading screens, car-park skins and decorative veils. Metal is also the default re-cladding material for refurbishment — light enough to over-clad existing structures.

Metal cladding draws on the rainscreen, product, fire and structural frameworks together.

Product, fire and performance

Composite panels are covered by EN 14509 (insulated panels) and product-specific standards with CE/UKCA marking; reaction-to-fire is classified to EN 13501-1 (with A2-s1,d0 the key threshold for cores in tall buildings) and external fire spread demonstrated where required by BS 8414 assessed to BR 135; many jurisdictions impose outright bans on combustible external-wall materials in tall residential buildings. System weather and structural performance follows the CWCT Standard and the EN cladding family; wind loading follows EN 1991-1-4 and structural design the Eurocodes.

Materials and finishes

Aluminium follows the EN 485 / EN 1396 (coil and sheet) standards; coated steel EN 10169; stainless EN 10088; finishes follow PVDF coating specifications (e.g. ECCA / AAMA 2605), QUALICOAT for powder coating and QUALANOD / EN ISO 7599 for anodising. Zinc and copper follow their own product standards (e.g. EN 988 for zinc).

Metal cladding scores well on circularity but variably on embodied carbon, and the fire-safety transition has reshaped its material story.

All the cladding metals are highly recyclable — aluminium, steel, zinc and copper are recovered and recycled with little loss of quality, and many products carry high recycled content and Environmental Product Declarations to EN 15804. Embodied carbon varies with the metal and its production route: recycled aluminium and steel score far better than primary, while copper and zinc have their own profiles offset by very long service lives and self-renewing patinas. Mechanically fixed metal cassettes are demountable, repairable and individually replaceable, supporting design for disassembly. The move from combustible PE cores to mineral-filled A2 cores improves fire safety but adds weight and mineral content; the most sustainable metal façade pairs a durable, recyclable metal and finish with a non-combustible build-up and demountable fixings.

Metal cladding involves panel/coil manufacturers, composite-panel makers, standing-seam and profiled-system houses, and the rainscreen carrier and fixing suppliers covered in the rainscreen entry. The visible panels are installed by specialist cladding contractors.

Panel & metal manufacturers

• Alucobond (3A Composites) Singen, Germany — ACM composite panels
• Reynobond / Reynolux (Arconic) aluminium composite & sheet
• Alpolic (Mitsubishi Chemical) composite (ACM/MCM) panels
• VMZINC (Umicore) Paris, France — architectural zinc
• Rheinzink Datteln, Germany — titanium-zinc cladding & roofing
• Kalzip Koblenz, Germany — aluminium standing-seam systems
• Kingspan Kingscourt, Ireland — insulated metal panels & façades
• Kme / Aurubis architectural copper

Coil, finishing & carrier systems

Coated coil and sheet come from mills and coil-coaters (Hydro, Novelis, ArcelorMittal, Tata Steel and others); finishes from PVDF and anodising specialists; and the rainscreen support systems and fixings from the carrier-system makers (SFS/NVELOPE, Nvelope, Fischer and similar) covered under Rainscreen Cladding. Türkiye-based producers including Asaş, Albond and Alumetal supply composite and coil products to regional markets.