Repair Systems — 03 — Facade & External Envelope
Hot-dip galvanised steel flat bar lintel
Technical product reference for hot-dip galvanised steel flat bar lintels for masonry facade remediation on Australian Class 2 strata buildings. Covers HDG-only flat bar lintels for shallow rebate inland masonry openings. Structural engineer confirmation of span and deflection capacity is mandatory before specifying.
What is a hot-dip galvanised steel flat bar lintel?
A hot-dip galvanised (HDG) steel flat bar lintel is a flat bar steel section zinc-coated by the hot-dip galvanising process to AS/NZS 4680, without a paint overcoat. The HDG-only system provides 15–25 years service life in inland C2/C3 environments. Flat bar lintels are used specifically for shallow rebate masonry openings where the structural depth within the reveal cannot accommodate an equal angle section, and are restricted to spans under 2 m due to the lower section modulus of the flat bar profile.
Product Reference
3 supplier systems — hot-dip galvanised steel flat bar lintels — scroll to view all
InfraBuild — Hot-dip galvanised flat bar lintel — shallow rebate openings
Hot-dip galvanised steel flat bar lintel — HDG only — shallow rebate — inland
System Description
InfraBuild supplies hot-dip galvanised flat bar sections compliant with AS/NZS 4680 for masonry lintel applications in shallow rebate openings in inland C2/C3 environments. The HDG-only system — without a paint overcoat — provides 15–25 year service life inland. Flat bar lintels are used where the window rebate geometry prevents the installation of an equal angle section. Spans are restricted to under 2 m due to the lower section modulus of flat bar compared to equal angle. A structural engineer must confirm section adequacy per AS 4100. Not suitable for coastal or C4/C5 environments.
Technical Properties
- Hot-dip galvanised to AS/NZS 4680 — minimum zinc coating mass confirmed by material test certificate
- 15–25 year inland service life in C2/C3 environments — shorter than duplex (HDG + paint) systems
- For shallow rebate openings where equal angle section cannot fit — lower section modulus than angle
Limitations
- Not suitable for coastal, marine or C4/C5 corrosivity environments — specify stainless steel flat bar for coastal applications
- Restricted to spans under 2 m — flat bar section modulus is lower than equal angle; engineer must confirm adequacy
- Shorter service life than duplex coated flat bar — 15–25 years HDG only vs 40–50 years HDG + paint
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
Lysaght / BlueScope — HDG flat bar lintel — standard flat bar range
Hot-dip galvanised steel flat bar lintel — HDG only — BlueScope/Lysaght sections — national distribution
System Description
Lysaght and BlueScope flat bar sections are available hot-dip galvanised to AS/NZS 4680 for masonry lintel applications in shallow rebate openings in inland C2/C3 environments. The HDG-only system provides 15–25 year service life inland. Lysaght/BlueScope sections are widely stocked by national structural steel merchants. A structural engineer must confirm the section size, bearing length and installation requirements per AS 4100 and AS 3700. Not suitable for coastal or marine-influenced environments.
Technical Properties
- HDG zinc coating to AS/NZS 4680 standard — quality-assured zinc coating from BlueScope-origin steel
- 15–25 year estimated inland service life in C2/C3 environments
- Standard flat bar range available nationally — readily stocked by structural steel merchants
Limitations
- Not suitable for coastal, marine or C4/C5 environments — stainless steel required for coastal applications
- Shorter service life than duplex coated systems — 15–25 years vs 40–50 years
- Structural engineer must confirm section adequacy, span capacity and bearing — flat bar is restricted to under 2 m
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
State-based masonry lintel fabricators — cut-to-length HDG flat bar lintels
Hot-dip galvanised flat bar lintel — cut to length — local fabrication — engineer's drawings
System Description
State-based masonry lintel fabricators supply cut-to-length hot-dip galvanised flat bar lintels fabricated to the structural engineer's drawings for shallow rebate masonry opening applications. The fabricator hot-dip galvanises the cut flat bar sections per the specification. Request a fabrication and coating certificate confirming AS/NZS 4680 compliance before accepting delivery. Not suitable for coastal environments — specify stainless steel for all coastal flat bar applications.
Technical Properties
- Cut to exact dimensions — ensures consistent bearing length at both ends per the engineer's specification
- Fabricated to engineer's drawings — flat bar dimensions and bearing requirements per the structural design
- HDG finish applied by fabricator — confirm AS/NZS 4680 compliance in purchase order
Limitations
- Structural engineer's drawings must be provided before ordering — do not order without confirmed structural design
- Request fabrication and coating certificate confirming AS/NZS 4680 compliance before accepting delivery
- Not suitable for coastal environments — confirm site corrosivity is C2/C3 inland
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
System Comparison
Side-by-side comparison of hot-dip galvanised steel flat bar 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 | HDG flat bar lintel | Hot-dip galvanised only | Standard flat bar stock | 15–25 yr inland C2/C3 | National — steel merchant | AS/NZS 4680 certified HDG | Shallow rebate — economy — short life |
| Lysaght / BlueScope | HDG flat bar lintel | Hot-dip galvanised only | Standard flat bar range | 15–25 yr inland C2/C3 | National — structural merchant | BlueScope-origin steel | Shallow rebate inland — economy |
| State fabricators | Cut-to-length HDG flat bar | HDG only — per spec | Engineer-specified | 15–25 yr inland C2/C3 | State-based — local fabrication | Exact dimensions — no waste | Non-standard shallow rebate openings |
Do not confuse hot-dip galvanised flat bar lintel with:
- Galvanised angle lintel — angle has higher section modulus than flat bar of the same nominal height; angle should be preferred where the opening geometry permits; flat bar is for shallow rebate openings only
- Galvanised channel lintel — PFC channel has much higher section modulus; for wide openings where flat bar and angle capacity is insufficient
- Stainless steel flat bar lintel — grade 316L for coastal and marine environments; required wherever the site is within 1 km of the coast or classified C4/C5
Disclaimer
This page provides general technical information only. Galvanised flat bar lintel section, span capacity and bearing must be confirmed by a structural engineer per AS 4100 and AS 3700. Flat bar deflection must be checked against L/500 under masonry load.