Repair Systems — 03
Arris Angle & Edge Replacement
Technical product reference for aluminium, stainless steel and PVC arris angle bead systems for replacement of damaged or missing render returns at external corners and edges of Class 2 strata facades in Australia.
What are arris angles and edge beads?
Arris angles — also called corner beads or render beads — are metal or PVC profiles embedded in the render coat at external corners of rendered masonry and concrete facades. They define the arris edge of the render return, protect the sharp corner from impact damage, and guide the render screed to a consistent plane on both faces. Without an arris bead, external render corners are prone to chipping, cracking and irregular profiles that trap moisture and deteriorate rapidly.
In Australian Class 2 strata facade remediation, arris angle failure is one of the most common defects observed during facade condition surveys. Older buildings frequently used mild steel or low-grade aluminium beads, which corrode under the render in coastal and moderately exposed conditions. The expanding corrosion products cause the render to crack and delaminate at the corner, producing the characteristic rust staining and spalled render at external corner returns that is visible on many unremediated strata facades. Remediation requires full removal of the corroded bead and affected render, with replacement using a bead of appropriate material for the exposure category.
Three materials are in common use for arris angle replacement in Australian facade remediation: 304 stainless steel for coastal and corrosive exposures (C4/C5), aluminium for standard inland exposures (C2/C3), and rigid PVC for sheltered non-corrosive applications. Material selection is governed by the atmospheric exposure category of the facade, classified using AS 2312, and must be confirmed as part of the facade remediation specification. Compliance with AS 3700 is required for the render system as a whole.
Do not confuse arris angles with:
- Corner tape (plasterboard / internal only) — mesh or paper tape used internally for plasterboard joints, not suitable for external render corners
- Movement joint profiles — expansion joint covers and profiles used at structural movement joints, not at render edge returns
- Stainless mesh — reinforcing mesh embedded inside render coats for crack resistance, not an edge or corner profile
Product Reference
3 products — 3 brands — arris angle and corner bead systems — scroll to view all
System Description
The Rondo Stainless Arris Angle is a 304 grade stainless steel render corner bead used for the protection and definition of external corners on rendered masonry and concrete facade substrates. It is the preferred product for facades located in coastal, marine or corrosive environments where aluminium or mild steel beads are not suitable due to accelerated corrosion under the render. The stainless angle is embedded in the render coat during application, providing a hard edge to the render return at the external corner and preventing chipping and damage at arris points. The perforated wings key into the render coat on both faces and provide mechanical bond. For Class 2 strata facade remediation where existing steel or aluminium arris beads have corroded and caused render staining or delamination, full removal and replacement with stainless is the preferred remedial approach in corrosive exposure zones. Confirm current product designation, sizing and availability with Rondo Building Services. Product range and designations are subject to revision — always obtain the current Rondo technical data sheet before specifying.
Technical Properties
- 304 stainless steel — corrosion-resistant — preferred for C4 and C5 exposure zones including coastal, marine and pool environments
- Perforated wings for mechanical key into render coat on both faces of the corner — compatible with sand cement, polymer-modified and acrylic render systems
- Hard arris edge protects render returns at external corners from impact damage and chipping
Limitations
- Higher cost than aluminium or PVC alternatives — use where corrosive exposure warrants the additional cost
- Requires full removal of existing corroded bead including all contaminated render before installation — do not render over existing corroded angles
- Stainless steel can still be subject to pitting corrosion in very high chloride environments (C5M marine) — confirm with Rondo for severe marine exposures
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
System Description
Trim-Tex PVC Corner Bead is a rigid PVC arris angle bead for external corners in rendered and plastered wall systems. PVC beads are inherently rust-free and will not cause render staining or delamination from corrosion of the bead body. They are suited to sheltered and non-coastal exterior applications where corrosive exposure is classified C1 to C3 and where the lightweight, easy-to-cut characteristics of PVC are advantageous. The perforated PVC wings embed in the render coat and provide mechanical key. The hard nose of the bead defines the arris and protects the render return from impact. PVC does not conduct heat differentially in the way that metal beads can, which may reduce thermally-induced stress cracking risk at the corner bead in some render systems. Note that PVC corner beads are generally not recommended for highly exposed coastal or corrosive facade applications as the PVC nose can become brittle with prolonged UV exposure over time, and PVC is not as dimensionally rigid as stainless steel in heavy render applications. Confirm suitability for the specific render system and exposure category with Trim-Tex Australia before specifying.
Technical Properties
- PVC material — rust-free and will not corrode, stain render or cause delamination from bead corrosion
- Lightweight and easy to cut to length on site — reduces installation time compared to metal beads
- Perforated wings provide mechanical key into render coat — compatible with standard sand cement and polymer-modified render systems
Limitations
- Not recommended for coastal, marine or corrosive exposure environments (C4/C5) — use stainless steel in these zones
- PVC can become brittle with long-term UV exposure in highly exposed uncoated facade conditions — confirm suitability for exposed applications
- Not as dimensionally rigid as metal beads in heavy or thick render applications — confirm for heavyweight render systems
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
System Description
The Rondo Aluminium Render Bead is the standard aluminium arris angle bead for external render corners in non-coastal and standard exposure facade applications. Aluminium is lighter than stainless steel and easier to cut on site, making it widely used for render bead applications in C2 and C3 exposure categories where corrosive exposure is not a primary concern. Aluminium render beads are embedded in the render coat during application with the perforated wings keying into the render on both faces. The hard aluminium nose defines the arris, provides impact resistance and guides the render screed to a consistent corner return. Aluminium beads are suitable for use with standard sand cement and polymer-modified render systems in sheltered to moderately exposed facade conditions. Aluminium should not be specified in coastal, marine or pool environments (C4/C5) where chloride-driven corrosion of the aluminium bead under the render can cause render staining, blistering and delamination. In these environments, 304 stainless steel arris angles are the correct specification. Confirm exposure category classification per AS 2312 before selecting bead material.
Technical Properties
- Aluminium construction — significantly lighter than stainless steel — easy to cut and handle on site
- Perforated wings for mechanical key into render on both faces — compatible with sand cement, polymer-modified and acrylic render systems
- Hard aluminium nose defines arris edge and guides render screeding to a consistent external corner profile
Limitations
- Not suitable for coastal, marine or pool environments (C4/C5) — aluminium will corrode under render in high chloride environments causing render staining and delamination
- Do not use in facades within approximately 1 km of breaking surf or in direct marine spray zones without confirmation from Rondo technical
- Requires full removal of existing corroded beads and affected render before installation — do not render over existing failed aluminium beads
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
System Comparison
Side-by-side technical comparison of arris angle and corner bead products for facade remediation. Confirm current product specifications with manufacturer TDS.
| Product | Brand | Material | Corrosion rating | Render system | Fixing method | Primary use |
|---|---|---|---|---|---|---|
| Rondo Stainless Arris Angle | Rondo | 304 stainless steel | C4 / C5 — coastal / marine | Sand cement, polymer-modified | Embedded in render — perforated wings | Coastal and corrosive exposure external corners |
| Trim-Tex PVC Corner Bead | Trim-Tex | Rigid PVC | C1 / C2 / C3 — non-coastal | Sand cement, polymer-modified | Embedded in render — perforated wings | Sheltered / non-coastal external corners |
| Rondo Aluminium Render Bead | Rondo | Aluminium | C2 / C3 — standard inland | Sand cement, polymer-modified, acrylic | Embedded in render — perforated wings | Standard non-coastal external corners |
Brand Equivalents
Arris angle equivalents across brands active in Australian Class 2 strata facade remediation.
| System type | Rondo | Trim-Tex |
|---|---|---|
| Stainless arris angle (coastal/exposed C4+) | Rondo Stainless Arris Angle | — |
| Aluminium arris angle (standard C2/C3) | Rondo Aluminium Render Bead | — |
| PVC corner bead (internal/sheltered) | — | Trim-Tex PVC Corner Bead |
Corrosion exposure selection
- In coastal and marine environments — and all facades within approximately 1 km of breaking surf or in direct marine spray — specify 304 stainless steel arris angles as a minimum. Aluminium and mild steel beads will corrode and fail in these zones.
- Pool environments — including buildings with rooftop or podium salt pools — must be treated as C4 or C5 corrosive exposure regardless of coastal proximity. Specify stainless steel arris angles in all such applications.
- In C2 and C3 standard inland exposures away from the coast, aluminium arris angles are appropriate and cost-effective. Confirm the exposure category classification per AS 2312 before specifying.
- PVC beads are suitable for sheltered and non-exposed applications (C1/C2) and where lightweight handling is advantageous — they are not recommended for fully exposed facade corners subject to long-term UV loading without confirmation of product suitability for the specific exposure.
Disclaimer
Information is general only. Arris angle selection must be confirmed against substrate type, exposure category, render system and the current manufacturer technical data sheet. In coastal and corrosive environments stainless steel arris angles are recommended. Confirm compliance with AS 3700. Do not rely on this reference as a substitute for professional advice.