Repair Systems — 03 — Facade & External Envelope
Jamb Flashing
Technical product reference for vertical jamb flashings at facade cladding panel openings — stainless grade 316 and aluminium L-profile and Z-profile jamb flashings sealing the vertical interface between cladding panels and window or door frames. Typically finished with a backer rod and sealant joint at the frame interface.
What are jamb flashing systems?
Jamb flashings seal the vertical side (jamb) reveals of windows and doors in rainscreen cladding systems — bridging the gap between the cladding panel edge and the window frame to prevent wind-driven water ingress at this vulnerable joint. Correct lapping sequence with head and sill flashings is as important as material selection.
Product Reference
4 product systems — jamb flashing — scroll to view all
System Description
316L stainless Z-section jamb flashings are factory-folded to the project-specific profile for window and door side (jamb) reveals in rainscreen cladding systems. The Z-section configuration provides a positive weather seal at the interface between the cladding system edge and the window frame — the outer leg laps over the cladding panel edge while the inner leg is fixed to the structural reveal. At the top, the jamb flashing laps under the head flashing; at the bottom, it laps over the sill flashing end dam. Correct lapping sequence is critical to prevent water ingress at corners.
Technical Properties
- Material: 316L stainless — 1.5 mm
- Profile: Z-section — 50 mm × 25 mm × 50 mm standard
- Factory CNC press-brake folded
Limitations
- Factory lead time 3–6 weeks — shop drawings required
- Lapping sequence critical — head over jamb over sill must be maintained
- Jamb must not be installed before sill — sequence error causes water ingress
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
Anodised Alum L-Section Jamb
L-Section Jamb Flashing — Anodised Aluminium
System Description
Factory-folded 6063-T5 anodised aluminium L-section jamb flashings (also called reveal flashings) are fixed to the structural jamb reveal and lap over the cladding panel edge at the opening side. The outer leg overlaps the cladding panel edge by minimum 20 mm, providing weather protection at the vulnerable vertical joint between cladding and opening. Anodised Class 2 (20 micron) provides corrosion resistance for coastal zones. Sealant (neutral cure silicone) is applied at the interface between the jamb flashing inner leg and the window frame.
Technical Properties
- Material: 6063-T5 aluminium
- Gauge: 1.6 mm
- Anodising: Class 2 — 20 micron
Limitations
- Not suitable for marine zone < 200 m — use SS316
- Anodising scratches during installation — protect until cladding complete
- Sealant at jamb-to-frame interface will fail within 15–20 years — inspect
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
System Description
Colorbond Ultra jamb reveal flashings are colour-matched to the building's Colorbond or FC panel palette — a key aesthetic requirement in residential facades where the side reveal of windows is prominent. Factory-folded in the same Colorbond colour as the head and sill flashings, these create a consistent, colour-coordinated opening surround. The outer leg overlaps the cladding panel edge by 20–25 mm and is retained with Colorbond-coloured pop rivets. Suitable for coastal zones (C4) up to 1 km from marine water.
Technical Properties
- Material: Colorbond Ultra — 0.55 mm BMT
- Profile: L-section — 50 × 50 mm or custom
- 27 standard Colorbond colours
Limitations
- Not suitable for marine zone < 1 km — use anodised alum or SS316
- Cut edges must be primed — Colorbond corrodes at cut edges
- Colour fades: not maintenance-free at 20-year horizon
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
Alum Jamb Flashing + EPDM
Jamb Flashing with EPDM Compression Seal
System Description
Aluminium jamb flashings with factory-integrated EPDM compression seal at the window frame interface eliminate the silicone sealant joint that is the most common jamb water ingress failure mode. The EPDM seal is bonded to the inner leg and compresses against the aluminium window frame as the flashing is fixed — accommodating differential thermal movement between the aluminium cladding flashing and the window frame without cracking or debonding. Suitable for high-specification facades where long-term water ingress risk at jambs must be minimised.
Technical Properties
- Material: 6063-T5 anodised aluminium
- EPDM: 3 mm bulb — 70 Shore A — factory bonded
- Profile: Z or L section to suit opening reveal
Limitations
- EPDM requires uniform contact with window frame — gaps > 2 mm will not seal
- EPDM cannot be replaced in field if damaged during installation
- Window frame must be installed first and plumb before jamb flashing fitted
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
System Comparison
Side-by-side comparison of jamb flashing systems. Confirm all product selections against the current manufacturer TDS before specifying.
| Product system | Brand | Material | Profile | Zone | EPDM seal | Colour match | Primary use |
|---|---|---|---|---|---|---|---|
| SS316 Z-Section Jamb | Metroll / Steel & Tube | 316L Stainless — 1.5 mm | Z-section | Marine | No | Mill/brushed SS | Marine zone — 50+ yr no-maintenance |
| Anodised Alum L-Section | Capral / Ullrich Aluminium | 6063-T5 Anodised — 1.6 mm | L-section | Coastal | No | Silver anodised / custom | Standard coastal cladding |
| Colorbond Jamb Reveal | Stratco / Metroll | Colorbond Ultra — 0.55 mm BMT | L-section | Coastal (C4) | No | 27 Colorbond colours | Colour-matched residential |
| Alum + EPDM Jamb | Ametalin / Capral Aluminium | 6063-T5 Anodised — 1.6 mm | Z or L section | Coastal | Yes | Silver anodised / custom | Eliminates sealant failure at frame |
Do not confuse jamb flashings with:
- Window reveal lining — internal MDF, plywood, or plasterboard lining at the window jamb; internal reveal materials serve a decorative purpose only and are not waterproofing elements — jamb flashings are external weather seals
- Aluminium window bead or stop bead — an aluminium extrusion used as a render stop or decorative bead at the window edge; a jamb flashing is a purpose-folded weatherproofing element that laps behind the window frame and integrates with the wall wrap
- Z-flashing used as a jamb — a horizontal Z-flashing profile is designed for head and sill locations; jamb flashings require a vertical L-section or Z-section with appropriate upstand and overlap into the wall system — different profile and installation detail
- Lead flashing used as a jamb seal — lead is prohibited for most new and remedial facade work in Australia; replacement jamb flashings must use aluminium, SS 316, or Colorbond depending on zone classification
Disclaimer
Information is general only. Jamb flashing profiles, leg dimensions, and sealant joint details must be confirmed by a facade engineer against the specific cladding and window system design. The sealant joint between the jamb flashing and window frame must accommodate thermal movement. Do not rely on this reference as a substitute for professional engineering advice.