Repair Systems — 03 — Facade & External Envelope
External Corner Flashing
Technical product reference for external corner flashings at facade cladding system corners — aluminium and stainless grade 316 L-profile, box, and extruded corner flashings at external corners where two cladding faces meet. Corner flashings must accommodate thermal movement and be compatible with the selected cladding panel system.
What are external corner flashing systems?
External corner flashings protect the most exposed elements of any cladded facade — the building corners, where wind-driven rain is most intense, panel edges are most vulnerable to impact damage, and water can enter from two directions simultaneously. Correct material selection and sealant detailing at corners is as important as at windows.
Product Reference
4 product systems — external corner flashings — scroll to view all
Anodised Aluminium Square External Corner Flashing
Square External Corner Flashing — Anodised Aluminium
System Description
Anodised 6063-T5 aluminium square external corner flashings (L-section corner) are installed at all external building corners where two cladding panel runs meet at 90°. The flashing overlaps both panel edges by minimum 25 mm, protecting the vulnerable corner edge of each panel from direct rain exposure and impact. The square 90° fold is factory CNC press-brake formed for consistent geometry. Available in anodised silver or custom powder-coat colour to match adjacent panels. Fixings: SS316 self-drilling screws through the flashing into the subframe rail at 450 mm centres.
Technical Properties
- Material: 6063-T5 aluminium
- Gauge: 1.6 mm; anodising: Class 2 — 20 micron
- Profile: L-section — 50 × 50 mm standard; custom widths to order
Limitations
- Not suitable for marine zone < 200 m — use SS316
- Panel edges must be cut square and accurately — gap visible at corner overlap
- Anodising scratches on site — protect during installation
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
System Description
316L stainless external corner flashings are specified for marine-zone facades (< 200 m from ocean) and severe coastal environments where aluminium flashings will corrode. Factory CNC press-brake folded to the exact project profile, 316L stainless corner flashings provide a 50+ year maintenance-free corner detail. The stainless finish (mill or brushed 2B) is compatible with architectural expressions where a metallic corner detail is an acceptable aesthetic. The corner flashing laps 25–30 mm over each panel edge and is fixed with SS316 rivets or screws.
Technical Properties
- Material: 316L stainless steel — 1.5 mm
- Profile: L-section — 50 × 50 mm or custom
- Factory CNC press-brake folded
Limitations
- Higher cost than aluminium — specify only where marine exposure confirmed
- Factory lead time: 3–6 weeks
- Stainless must be isolated from aluminium subframe — galvanic corrosion
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
Colorbond External Corner Flashing
External Corner Flashing — Colorbond Steel
System Description
Colorbond Ultra external corner flashings are colour-matched to the building's Colorbond palette — the most common corner flashing in Australian residential cladding. Factory-folded in matching Colorbond colour, these flashings create an architectural corner detail that integrates with the Colorbond Walling colour scheme. Suitable for coastal zones (C4) up to 1 km from marine water. Colorbond-coloured pop rivets maintain the colour consistency at fixing points. Used as part of a coordinated set with matching head, sill, jamb, and base weep flashings.
Technical Properties
- Material: Colorbond Ultra — 0.55 mm BMT
- 27 standard Colorbond colours
- Profile: L-section — 50 × 50 mm standard
Limitations
- Not suitable for marine zone < 1 km — use SS316 or anodised aluminium
- Cut edges corrode — prime within 24 hr
- Colour fades over 10–15 years — not maintenance-free
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
Aluminium Mitred Corner Trim — Custom Angle
Mitred Corner Trim — Custom Angle Aluminium
System Description
Custom-folded aluminium corner trims for non-standard angles (acute < 90° or obtuse > 90°) in angular facade designs and radius corners. CNC press-brake folding can produce any angle to the project-specific geometry — shop drawings required. The mitred corner trim is typically anodised or powder-coated to match the adjacent cladding panels. Radius corners require a different forming process (roll forming) and must be confirmed with the manufacturer. Used in contemporary architectural facades where the building corner is a design feature.
Technical Properties
- Material: 6063-T5 aluminium
- Gauge: 1.6 mm or 2.0 mm
- Custom fold angle: any angle from shop drawing
Limitations
- Shop drawings required — changes add 1–2 weeks to lead time
- Radius corners require roll forming — not all fabricators have this capability
- Obtuse corners (> 135°) are difficult to fold with consistent radius
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
System Comparison
Side-by-side comparison of external corner flashing systems. Confirm all product selections against the current manufacturer TDS before specifying.
| Product system | Brand | Material | Profile | Zone | Custom angle | Colour match | Primary use |
|---|---|---|---|---|---|---|---|
| Anodised Alum Square Corner | Capral / Ullrich | 6063-T5 Anodised | 90° L-section | Coastal | No | Silver / custom anodise | Standard coastal 90° corner |
| SS316 Corner Flashing | Metroll / Steel & Tube | 316L Stainless | 90° L-section | Marine | No | Mill / brushed SS | Marine zone 50+ yr |
| Colorbond Corner Flashing | Stratco / Metroll | Colorbond Ultra | 90° L-section | Coastal (C4) | No | 27 Colorbond colours | Colour-matched residential |
| Mitred Custom Trim | Capral / Metroll | 6063-T5 Anodised | Any angle | Coastal | Yes | Any RAL powder-coat | Acute / obtuse / radius corners |
Do not confuse external corner flashings with:
- Internal corner flashings — L-section pressed inward to weatherproof a re-entrant corner; external corners require an outward-facing L-section or purpose-folded corner cap — mixing internal and external corner profiles creates weathering failures
- Render corner bead (plaster bead) — a thin perforated aluminium or PVC bead used to reinforce external render at corners; a render bead is not a weatherproofing element and must not be used as a cladding corner flashing
- PVC corner trim — combustible PVC corner moulding used in internal joinery and some lightweight cladding; on NCC Type A and Type B buildings, combustible facade trim components must not be used at corners where fire spread or external weather exposure is a concern
- Aluminium corner trim installed without sealant at panel edges — corner flashings must be installed with compatible sealant at panel abutments to prevent water ingress at the flashing-to-panel interface, particularly at the top and exposed edges
Disclaimer
Information is general only. External corner flashing profiles, leg dimensions, and fixing methods must be confirmed by a facade engineer against the specific cladding system design and panel movement requirements. Corner flashings at high-wind-load buildings require additional engineering consideration. Do not rely on this reference as a substitute for professional engineering advice.