Repair Systems — 04 — Roofing Defects
Zincalume sheet replacement systems
Zincalume is BlueScope Steel's unpainted AZ150 aluminium-zinc-silicon alloy coated steel sheet, available in the same corrugated and trapezoidal profiles as Colorbond. Specified where a natural metallic finish is required or acceptable. Requires isolation from copper, lead and fresh concrete — critical constraints that must be reviewed on any building where those materials are present.
What is Zincalume sheet replacement?
Zincalume is BlueScope Steel's brand name for steel sheet coated with an AZ150 aluminium-zinc-silicon alloy, without a Colorbond paint finish. The corrugated (Custom Orb) and trapezoidal (Trimdek) profiles are available in Zincalume as well as Colorbond. Zincalume sheet is specified where a natural metallic finish is required or acceptable — industrial buildings, concealed roof areas, agricultural structures and some heritage applications.
Technical Reference
AZ150 coating properties, galvanic compatibility, concrete contact prohibition and Zincalume vs Colorbond selection
Product Reference
3 products — Lysaght corrugated, Lysaght Trimdek and Stramit equivalent — all in Zincalume substrate
Lysaght Custom Orb — Zincalume
Corrugated Zincalume steel sheet; AZ150 coating; 76mm corrugation pitch; 762mm cover width; unpainted metallic finish; AS 1562.1
Product type
Corrugated Zincalume steel sheet — 762mm cover — AS 1562.1
System description
Lysaght Custom Orb in Zincalume steel is the corrugated (sinusoidal 76mm pitch) profile in an unpainted AZ150 Zincalume substrate rather than Colorbond paint finish. The AZ150 coating is a zinc-aluminium-silicon alloy applied to BlueScope steel that provides corrosion protection without a paint system. The profile is dimensionally identical to Colorbond corrugated Custom Orb — same 76mm corrugation pitch and 762mm nominal cover. Used where a natural metallic finish is required, specified, or preferred, or where concealed roof areas do not require a paint finish.
Technical properties
- Profile: corrugated (sinusoidal), 76mm pitch, 762mm cover width
- Substrate: BlueScope Zincalume steel — AZ150 coating (150g/m² zinc-aluminium-silicon alloy)
- Finish: unpainted metallic silver-grey; no Colorbond paint system
- BMT: 0.42mm, 0.48mm; confirm additional gauges from Lysaght
- AS 1562.1 compliant — same span tables as corrugated Colorbond equivalent
- Dimensionally interchangeable with Colorbond Custom Orb for profile matching
- Screw and washer fixing — same fixing pattern as Colorbond corrugated
Limitations
- No paint finish — not a substitute where Colorbond colour finish is required
- NOT compatible with copper, lead or copper alloy components — galvanic corrosion risk; must be isolated
- NOT suitable for direct contact with fresh concrete, mortar, or calcium-silicate products
- Not recommended for highly corrosive environments (C5/industrial/severe coastal) without engineer review
- Not suitable for heated swimming pool enclosures or aggressive chemical environments
Procurement
Lysaght branches and authorised distributors nationally. Available as standard stock item through major roofing steel merchants.
View TDS / product pageConfirm suitability with the current manufacturer TDS before specifying or applying.
Lysaght Trimdek — Zincalume
Trapezoidal Zincalume steel sheet; AZ150 coating; 35mm rib height; 762mm cover width; unpainted metallic finish; AS 1562.1
Product type
Trapezoidal Zincalume steel sheet — 762mm cover — AS 1562.1
System description
Lysaght Trimdek in Zincalume steel is the high-rib trapezoidal profile in an unpainted AZ150 Zincalume substrate. The profile is dimensionally identical to Colorbond Trimdek — 35mm rib height, 762mm cover, pan-fixed. Used where a trapezoidal Zincalume profile is specified (industrial, agricultural, concealed structural areas, or heritage applications requiring bare metal). Provides the structural advantages of the Trimdek profile without a painted finish.
Technical properties
- Profile: trapezoidal (high-rib), 35mm rib height, 762mm cover width
- Substrate: BlueScope Zincalume steel — AZ150 coating
- Finish: unpainted metallic silver-grey
- BMT: 0.42mm, 0.48mm; confirm from Lysaght TDS
- AS 1562.1 compliant — confirm against current Lysaght Trimdek Zincalume span tables
- Pan-fixed — same fixing layout as Colorbond Trimdek
Limitations
- Unpainted — not a substitute where Colorbond colour finish is required
- Galvanic isolation required from copper, lead, and copper alloy components
- Not suitable for contact with fresh concrete, mortar or calcium-silicate products
- Confirm availability in Zincalume substrate with Lysaght — not all Trimdek gauges available in Zincalume at all branches
Procurement
Lysaght branches nationally. Confirm Zincalume Trimdek availability and lead times with the local Lysaght branch before specifying — may require order vs standard stock.
View TDS / product pageConfirm suitability with the current manufacturer TDS before specifying or applying.
Stramit (Zincalume equivalent)
Corrugated and trapezoidal Zincalume steel sheet — Stramit equivalent profiles in unpainted AZ150 Zincalume substrate; confirm product name and availability from Stramit
Product type
Zincalume steel sheet — corrugated or trapezoidal — AS 1562.1
System description
Stramit produces corrugated and trapezoidal steel roofing sheets in Zincalume substrate as well as Colorbond. The Zincalume products use the same BlueScope AZ150 coating and are dimensionally compatible with equivalent Lysaght profiles. Confirm the current Stramit product name, available gauges, and branch stock availability before specifying — product names may differ from Lysaght and not all profiles are stocked in Zincalume at every branch.
Technical properties
- Substrate: BlueScope Zincalume steel — AZ150 coating
- Profiles available: corrugated and trapezoidal (confirm from Stramit TDS)
- AS 1562.1 compliant — confirm via Stramit TDS
- BMT: 0.42mm standard — confirm options from Stramit
Limitations
- Confirm current product name and Zincalume availability at local Stramit branch before specifying
- Same galvanic isolation requirements as Lysaght Zincalume products — isolate from copper, lead and alloys
- Not suitable for contact with fresh concrete, mortar or calcium-silicate
Procurement
Stramit branches nationally. Confirm Zincalume product availability and lead times with local Stramit branch.
Confirm suitability with the current manufacturer TDS before specifying or applying.
Brand Equivalence
Zincalume products share the same AZ150 substrate across manufacturers — profile selection and supplier determines the choice.
| Product A | Product B | Equivalence note |
|---|---|---|
| Lysaght Custom Orb — Zincalume | Stramit Corrugated — Zincalume | Dimensionally equivalent corrugated profiles in the same AZ150 Zincalume substrate. Interchangeable for replacement work on existing corrugated Zincalume roofs. Confirm current product name with Stramit. |
| Lysaght Trimdek — Zincalume | Stramit (trapezoidal Zincalume) | Dimensionally equivalent trapezoidal profiles in Zincalume substrate. Interchangeable for profile. Confirm current Stramit product name and availability in Zincalume substrate before specifying. |
| Zincalume (any profile) | Colorbond (same profile) | NOT interchangeable where a paint finish is required. Zincalume and Colorbond use the same BlueScope steel base and AZ150 coating — the difference is the absence of a Colorbond paint top coat on Zincalume. Confirm with strata committee and heritage adviser before substituting. |
System Comparison
Corrugated Zincalume vs Trimdek Zincalume vs Stramit equivalent. Confirm all details against current manufacturer TDS.
| Attribute | Custom Orb — Zincalume | Trimdek — Zincalume | Stramit (Zincalume) |
|---|---|---|---|
| Substrate | Zincalume AZ150 | Zincalume AZ150 | Zincalume AZ150 |
| Profile | Corrugated (sinusoidal) | Trapezoidal (Hi-Rib) | Corrugated or trapezoidal |
| Cover width | 762mm | 762mm | 762mm (confirm TDS) |
| Paint finish | None (unpainted) | None (unpainted) | None (unpainted) |
| BMT standard | 0.42mm / 0.48mm | 0.42mm / 0.48mm | 0.42mm (confirm) |
| AS 1562.1 | Compliant | Compliant | Compliant |
| Cu/Pb contact | Isolate — galvanic risk | Isolate — galvanic risk | Isolate — galvanic risk |
Do not confuse Zincalume with:
- Colorbond steel — the same BlueScope AZ150 base, but with a Colorbond paint finish applied over the alloy coating. Not interchangeable where a colour finish is required or where strata by-laws specify painted sheet.
- Galvanised iron (GI) sheet — an older product with a hot-dipped zinc coating only (no aluminium alloy). No longer used in new or replacement work in Australia. GI is not compatible with Zincalume and should not be specified as a replacement.
- Natural zinc sheet (VM Zinc, Rheinzink) — pure zinc (not alloyed with aluminium) used for standing-seam heritage and premium applications. Completely different material, different forming method, different design life and installation requirements.
Disclaimer
This page provides general technical information only. Final product selection must be confirmed against the current manufacturer TDS, galvanic compatibility assessment, corrosion environment classification, AS 1562.1 requirements, structural engineer sign-off, and installer warranty conditions. Do not rely on this reference as a substitute for professional engineering or roofing consultant advice.