Repair Systems — 03 — Facade & External Envelope
Duplex coated steel angle lintel
Technical product reference for duplex coated steel angle lintels for masonry facade remediation on Australian Class 2 strata buildings. Covers HDG plus epoxy paint angle lintels for inland C2/C3 masonry opening support. Structural engineer specification is mandatory for all lintel replacements.
What is a duplex coated steel angle lintel?
A duplex coated steel angle lintel is a hot-dip galvanised (HDG) equal angle steel section with an epoxy paint overcoat applied over the zinc coating. The combination of HDG zinc layer and an epoxy paint topcoat — the "duplex system" — provides a service life of 40–50 years in inland C2/C3 environments, substantially longer than the 15–25 years achievable with hot-dip galvanising alone. Duplex coated angle lintels are the standard specification for masonry lintel replacement on Class 2 strata buildings in non-coastal Australian environments.
Product Reference
3 supplier systems — duplex coated steel angle lintels — scroll to view all
InfraBuild — Duplex coated steel angle lintel — 75×75×6 mm standard
Duplex coated steel angle lintel — HDG + epoxy — AS/NZS 4680 — national distribution
System Description
InfraBuild supplies hot-dip galvanised equal angle sections compliant with AS/NZS 4680, finished with an epoxy paint overcoat to form a duplex coating system for masonry lintel applications. The duplex system — hot-dip galvanising plus epoxy paint — provides a significantly longer service life than galvanising alone: typically 40–50 years in inland C2/C3 environments. The 75×75×6 mm equal angle is the standard section for masonry openings up to approximately 2–2.5 m, but section selection must be confirmed by a structural engineer per AS 4100 for the actual span, load and bearing conditions. InfraBuild has national distribution through steel merchant branches — confirm branch stock before specifying. Not suitable for coastal or C4/C5 environments where stainless steel lintels are required.
Technical Properties
- Duplex coating system — HDG (AS/NZS 4680, 600 g/m² minimum) plus epoxy paint overcoat — significantly extends service life over galvanised-only systems
- 40–50 year inland service life in C2/C3 inland environments when the epoxy overcoat is maintained — significantly longer than galvanised-only (15–25 yr)
- AS/NZS 4680 compliant hot-dip galvanising — minimum zinc coating mass confirmed by certification from InfraBuild
Limitations
- Not suitable for coastal, marine or C4/C5 corrosivity environments — specify grade 316L stainless steel angle lintel for all coastal applications
- Section size must be designed by a structural engineer per AS 4100 — do not assume 75×75×6 is adequate without engineering confirmation for the actual span and load
- Bearing length at each end must comply with the structural engineer's specification and AS 3700 — minimum 100 mm typical but confirm for project
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
Lysaght / BlueScope — HDG + epoxy angle lintel — standard angle sections
Duplex coated steel angle lintel — HDG + epoxy — BlueScope/Lysaght sections — national distribution
System Description
Lysaght and BlueScope structural steel sections — including equal angle (EA) — are available hot-dip galvanised to AS/NZS 4680 with an epoxy paint overcoat applied by merchant or fabricator to form a duplex coating system for masonry lintel applications. Lysaght/BlueScope sections are widely stocked by national structural steel merchants and distributors across all Australian states. The duplex system delivers 40–50 year inland service life in C2/C3 environments. A structural engineer must confirm the section size, bearing length and installation requirements per AS 4100 and AS 3700 before ordering. Not suitable for coastal or marine-influenced environments — confirm C2/C3 corrosivity classification for the project site before specifying duplex over stainless.
Technical Properties
- HDG + epoxy paint duplex system — zinc coating to AS/NZS 4680 standard with epoxy paint overcoat for extended service life
- 40–50 year estimated inland service life — substantially longer than galvanised-only systems in C2/C3 environments
- BlueScope-origin steel sections — quality-assured Australian steel production from a major domestic manufacturer
Limitations
- Not suitable for coastal, marine or C4/C5 corrosivity environments — stainless steel angle lintel required for coastal applications
- Structural engineer must design and certify lintel section, span and bearing — do not select section without engineering confirmation
- Epoxy overcoat must be inspected and touched up if damaged during installation — the paint film is essential to the duplex system life
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
State-based masonry lintel fabricators — cut-to-length duplex coated angle lintels
Duplex coated steel angle lintel — cut to length — local fabrication — engineer's drawings
System Description
State-based masonry lintel fabricators supply cut-to-length duplex coated angle lintels fabricated to the structural engineer's drawings. This approach is used when the required lintel length or section size is not available as standard stock, or when the project requires lintels fabricated to precise dimensions with a specified duplex coating system. The fabricator hot-dip galvanises the cut sections and applies an epoxy paint overcoat per the specification. Request a fabrication and coating certificate confirming AS/NZS 4680 compliance before accepting delivery. Confirm the fabricator's HDG bath dimensions are adequate for the required lintel lengths before placing an order. Not suitable for coastal environments — specify stainless steel for coastal applications.
Technical Properties
- Cut to exact length — avoids wastage and ensures consistent bearing length at both ends per the engineer's specification
- Fabricated to engineer's drawings — section, length, bearing plates and any intermediate stiffeners per the structural design
- HDG + epoxy paint duplex system applied by fabricator — confirm coating specification in the purchase order
Limitations
- Confirm the fabricator's HDG bath can accommodate the required lintel lengths before ordering — bath length limits maximum lintel length
- Request fabrication and coating certificate confirming AS/NZS 4680 compliance — do not accept delivery without certification
- Not suitable for coastal environments — confirm site corrosivity classification is C2/C3 before specifying duplex instead of stainless
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
System Comparison
Side-by-side comparison of duplex coated steel angle lintel systems. Confirm all selections against the structural engineer's design and request AS/NZS 4680 certificates before accepting delivery.
| Supplier | Product | Coating | Sections | Service life | Distribution | Key feature | Primary use |
|---|---|---|---|---|---|---|---|
| InfraBuild | Duplex angle lintel | HDG + epoxy paint | 75×75×6 mm EA standard | 40–50 yr inland C2/C3 | National — steel merchant branches | AS/NZS 4680 certified HDG | Standard masonry opening — inland |
| Lysaght / BlueScope | Duplex angle lintel | HDG + epoxy paint | Standard EA range | 40–50 yr inland C2/C3 | National — structural merchant | BlueScope-origin steel | General masonry lintel — inland |
| State fabricators | Cut-to-length duplex angle | HDG + epoxy — per spec | Engineer-specified | 40–50 yr inland C2/C3 | State-based — local fabrication | Exact length — no waste | Non-standard spans or sections |
Do not confuse duplex angle lintel with:
- Duplex flat bar lintel — flat bar has a lower section modulus than equal angle of the same height; restricted to spans under 2 m and shallow rebate openings where an angle section cannot fit
- Duplex channel lintel — parallel flange channel (PFC) has a higher section modulus than equal angle; used for wide openings or heavily loaded masonry where an angle section is insufficient
- Galvanised-only angle lintel — hot-dip galvanised with no paint overcoat; shorter service life of 15–25 years inland; not a duplex system
- Stainless steel angle lintel — grade 316L stainless for coastal and marine environments; more expensive and only required where galvanised or duplex coated systems cannot achieve the required service life
- Concrete lintel — precast or in-situ reinforced concrete; different material, different structural behaviour, different application
Disclaimer
This page provides general technical information only. Duplex coated steel angle lintel design, section size, bearing length and installation must be specified and certified by a structural engineer against project-specific span, load and corrosivity conditions per AS 4100 and AS 3700.