Metal wall cladding has moved well beyond the farm shed. Architects and builders are now specifying corrugated steel, standing seam panels and board-and-batten profiles on residential, commercial and mixed-use facades where the priorities are non-combustibility, longevity and low maintenance. The profiles available through BlueScope, Lysaght, Stramit and Fielders give designers a wide palette, but each profile has specific installation requirements that determine whether the facade performs for thirty years or starts causing problems in three.
This post covers the main profile families, how orientation affects both aesthetics and detailing, and the substrate system that sits behind the steel.
Why Metal Cladding on Walls
Steel cladding in COLORBOND or ZINCALUME is non-combustible and satisfies the requirements of AS 1530.1 for combustibility testing. Under NCC 2025, buildings above two storeys in certain occupancy classes must use non-combustible external wall cladding, and metal sheeting on a non-combustible substrate meets that requirement where aluminium composite panels with polyethylene cores do not. The post on this site covering ACP bans and AS 1530.1 goes into that compliance question in detail.
Beyond compliance, steel cladding suits coastal environments when the correct steel grade and fastener class are matched to the site's corrosivity category. COLORBOND steel uses a zinc-aluminium-magnesium alloy substrate (BlueScope's AZ150 coating on most profiles) with a baked-on paint system that resists salt spray far better than uncoated or painted mild steel. In C4 and C5 coastal corrosivity zones, specifiers should confirm the substrate grade with BlueScope's corrosion zone mapping and use Class 4 stainless or hot-dip galvanised fasteners throughout.
Profile Families for Wall Applications
Corrugated and Mini-Orb
Corrugated sheeting (the classic 76/18 sinusoidal profile) and Mini-Orb (a tighter 17/7 corrugation) are the most widely recognised profiles in Australian construction. Both are face-fixed with screws through the crown of the corrugation into the batten or framing behind. On walls, the exposed fastener is part of the aesthetic for many projects, particularly in rural and industrial-influenced residential design.
Corrugated steel on walls tolerates both vertical and horizontal orientation. Vertical corrugations shed water naturally and require a head flashing at the top of each sheet run and a base flashing or kick-out at the bottom. Horizontal corrugations create a more contemporary, linear look but require careful detailing at horizontal laps because water can track along the corrugation trough rather than draining clear. Each horizontal lap needs a sealant bead and a positive drainage path to the cavity.
Mini-Orb is more commonly used for feature panels, infill sections and smaller residential facades rather than whole-building cladding, largely because the shallow corrugation depth gives less rigidity over long spans.
Trimdek and Spandek
Trimdek (a 35mm deep trapezoidal rib profile at 200mm centres) and Spandek (a shallower, wider-rib profile) are both designed primarily as roofing profiles but are regularly used on walls, particularly on commercial and industrial buildings and on residential facades where a flat, ribbed panel aesthetic is wanted.
Both profiles are face-fixed through the pan (the flat section between ribs) on wall applications, unlike roof applications where fixings go through the rib crest. Pan fixing on walls reduces the visual impact of fasteners and suits the cleaner aesthetic most designers are after. The trapezoidal rib on Trimdek reads as a strong shadow line, especially in raking light, which makes it a popular choice for facades where surface articulation is part of the design intent.
Horizontal Trimdek on a facade produces a strong datum line across the building. Vertical Trimdek reads more like a fluted column. The orientation choice affects the flashing strategy significantly, covered below.
Concealed-Fix Standing Seam and Interlocking Panels
Concealed-fix profiles, including Lysaght Klip-Lok, Stramit Longline 305 and various Fielders products, use a clip fixed to the substrate that engages with the rib of the sheet. No fastener penetrates the face of the panel. This gives a clean, uninterrupted surface with no exposed screw heads, which suits contemporary residential and commercial facades where a minimal aesthetic is specified.
On walls, concealed-fix profiles are almost always run vertically. The clip system allows thermal movement along the sheet length without buckling, which matters on tall facades exposed to direct sun. A dark COLORBOND colour on a north or west-facing wall can reach surface temperatures above 70°C on a summer afternoon; a face-fixed sheet on a long vertical run would have nowhere for that expansion to go.
Interlocking flat panels, sometimes called secret-fix or snap-lock panels, produce a flush surface with no visible ribs at all. These are common on high-end residential and commercial facades where the design calls for a monolithic metal surface. They require a more precisely prepared substrate than ribbed profiles because any substrate irregularity telegraphs through the flat panel face.
Board-and-Batten Profiles
Several manufacturers produce profiles that replicate the shadow line and proportions of traditional timber board-and-batten cladding in steel. Fielders KingFlor and similar products in this category use a deep, narrow rib with a flat pan that reads visually as individual boards. These profiles are almost always run vertically and are particularly common on residential projects where a contemporary rural or coastal aesthetic is wanted without the maintenance burden of actual timber.
The detailing at window and door reveals with board-and-batten profiles requires careful flashing work because the deep rib creates a shadow gap that must be closed at penetrations without compromising the drainage path.
Vertical vs Horizontal Orientation
Orientation is both an aesthetic and a technical decision. Vertical cladding sheds water by gravity along the sheet length and is the default for most profiles. The main flashing requirements are a head flashing at the top of the wall (where the cladding meets the soffit, parapet or roof line) and a base flashing or ground clearance detail at the bottom.
Horizontal cladding produces a layered, linear facade that many architects prefer for its reference to weatherboard traditions and its ability to emphasise the horizontal datum of floor levels. The technical trade-off is that horizontal laps must be detailed to prevent water ingress. Each horizontal lap needs a minimum 20mm overlap (check the manufacturer's installation guide for the specific profile) and a sealant bead at the lap. More importantly, the cavity behind the cladding must drain freely because some water will always find its way past the laps.
At window and door openings, horizontal cladding requires a sill flashing that directs water out past the face of the cladding, not back into the wall. A simple apron flashing is not enough; the sill flashing must have an upstand into the window frame and a drip edge that clears the cladding below. Jamb flashings at the sides of openings need to accommodate the horizontal sheet ends without creating a pocket that traps water.
Vertical cladding at openings is somewhat simpler: the head flashing above the window directs water onto the face of the cladding below, and the jamb flashings close the sheet ends at each side. The base of the opening still needs a sill flashing with a positive drip edge.
The Cavity System Behind the Cladding
The profile choice and orientation are visible decisions. The cavity system behind the cladding is invisible but determines whether the facade performs or fails.
A drained and ventilated cavity is the standard requirement for metal wall cladding in Australia. The cavity sits between the back of the cladding and the face of the breather membrane, typically 20 to 25mm wide, created by the batten or top-hat section that the cladding fixes to. The cavity serves two purposes: it provides a drainage path for any water that penetrates the cladding, and it allows air movement that dries out any moisture before it reaches the structural frame.
The breather membrane behind the cavity is a vapour-permeable sarking that blocks liquid water but allows water vapour to pass through. Under NCC 2025, condensation management in wall assemblies is a compliance requirement, not just a best-practice recommendation. A breather membrane on the warm side of the insulation, combined with a ventilated cavity on the cold side, is the standard approach for metal-clad walls in most Australian climate zones.
Insulation sits between the framing members, behind the membrane. For metal-framed walls, a thermal break between the frame and the cladding batten is worth specifying because steel conducts heat readily and a continuous metal path from the exterior cladding to the interior lining will degrade the wall's thermal performance significantly.
Battens and top-hat sections used to create the cavity must be compatible with the cladding material. Fixing COLORBOND steel cladding to untreated timber battens in a wet or coastal environment is a corrosion risk at the contact point. Treated pine (H3 minimum for above-ground sheltered applications, H4 where exposed to wetting) or powder-coated steel top-hats are the standard choices.
Fasteners and Sealants
Fastener selection for wall cladding follows the same corrosivity-zone logic as roofing. Class 3 fasteners are the minimum for most inland applications; Class 4 stainless steel or hot-dip galvanised fasteners are required in C4 and C5 coastal zones. The fastener must be compatible with both the cladding and the substrate: a stainless screw into a zinc-coated steel top-hat in a wet environment can set up a galvanic couple if the metals are too far apart on the galvanic series. Refer to the fastener manufacturer's compatibility data and BlueScope's installation guides.
Sealants at laps, penetrations and flashings should be specified as neutral-cure silicone or polyurethane types compatible with COLORBOND paint systems. Acetic-cure silicones (the ones that smell of vinegar when curing) can attack the paint system and cause adhesion failure at the joint.
Specifying Metal Cladding
For architects and designers, the specification sequence for a metal-clad facade runs: profile selection, orientation, colour and substrate grade, cavity and batten system, breather membrane, insulation, fastener class, flashing details at head, base and all penetrations, and sealant specification. Each decision affects the next.
ACS supplies COLORBOND and ZINCALUME sheeting in corrugated, Trimdek, Spandek and a range of concealed-fix profiles, cut to length for wall applications, along with matched flashings, fasteners, sarking and insulation. For large or commercial facade projects, a request-a-quote through acsupplies.com.au allows the trade desk to confirm profile availability, lead times and delivery options for long material to site.