The Complete Guide to Aluminium Curtain Wall Systems
Curtain wall systems are one of the most technically demanding applications in modern architecture. They define building aesthetics, control thermal performance, resist wind and water, and must perform flawlessly for decades. At the centre of every high-performance curtain wall is the aluminium extrusion profile, and choosing the right system makes all the difference.
What Is an Aluminium Curtain Wall System?
A curtain wall is a non-structural cladding system attached to the building’s primary structure. It bears no floor loads but must resist wind pressure, thermal movement, water infiltration, and seismic loads. Aluminium is the material of choice because it combines high strength-to-weight ratio, excellent corrosion resistance, precise extrudability, and long-term durability.
Modern curtain wall systems come in two primary types:
- Stick systems: Components assembled on-site, economical and flexible but labour-intensive
- Unitised systems: Pre-assembled panels fabricated off-site, faster installation, higher quality control
What Is an Aluminium Curtain Wall System?
Mullions and Transoms
Mullions are the vertical load-bearing members; transoms are horizontal connectors. Together they form the structural grid. Profile geometry, including thermal break design, wall thickness, and hollow section configuration, determines the structural and thermal performance of the entire system
Pressure Plates and Caps
These extruded components clamp glazing in place and form the visual face of the curtain wall. They require close dimensional tolerance to maintain uniform sight lines across large facades and must be compatible with the gasket and sealant systems used.
Thermal Break Technology
High-performance facades require thermally broken profiles, aluminium sections separated by polyamide insulation strips to reduce thermal conductivity. This is critical for buildings targeting LEED, BREEAM, or Green Star certification.
Structural Performance Requirements
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Performance Parameter
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Typical Requirement
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Alumex Capability
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|---|---|---|
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Wind Load Resistance
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Up to 3.0 kPa
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Designed to project specification
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Water Penetration
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Zero at design pressure
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System-tested per EN 12154
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Air Permeability
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Class A4
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Meets EN 12153 requirements
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Thermal Performance
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Uf ≤ 1.8 W/m²K
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Available with polyamide thermal break
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Surface Finish
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30-year warranty
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Qualicoat-certified powder coating
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Selecting the Right Profile Series
Choosing between profile series involves balancing structural span requirements, glazing weight, thermal performance targets, and budget.
- Mullion depth: Deeper profiles handle greater wind spans but affect interior space and facade aesthetics
- Thermal break configuration: Wider breaks improve insulation but require careful structural analysis
- Finish compatibility: All powder-coated profiles must be Qualicoat-certified for warranty compliance
- Fixing method: Back-bolt, mechanical fix, or structural silicone bonding, each affects profile design
Surface Finishing for Curtain Walls
The surface finish of a curtain wall profile is critical to both aesthetics and durability. For large facades, colour consistency across every profile batch is non-negotiable. Alumex’s SAT-CUBE Trevisan vertical powder coating facility, the first of its kind in South Asia, ensures that profiles up to 7 metres receive perfectly uniform coating thickness from top to bottom.
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Finish Type
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Best Application
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Durability
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|---|---|---|
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Architectural Powder Coat
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Standard facades, high-rises
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30 years (Qualicoat)
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Anodizing
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Coastal, high-humidity environments
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25-30 years (Qualanod)
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Wood-Effect Sublimation
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Natural-look facades, hospitality
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20+ years with UV protection
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Satin Finish
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Luxury residential, premium commercial
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Long-term with proper maintenance
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Common Design Mistakes to Avoid
- Specifying profiles without confirmed thermal break performance for the project’s climatic zone
- Ignoring differential movement between aluminium and structural frame, which causes sealant failure
- Under-sizing mullion depth for the actual wind load at the building height and location
- Mixing profile series between suppliers, as tolerance differences cause misalignment
- Selecting finish without Qualicoat certification, voiding the manufacturer’s performance warranty
Working With Alumex on Curtain Wall Projects
Alumex provides end-to-end support for curtain wall projects, from profile selection and die manufacturing for custom sections, through to certified surface finishing and export-ready packaging. Our technical team works directly with architects and facade engineers to review profile geometries, structural calculations, and finish specifications before production begins.
To discuss your curtain wall project requirements with our technical team, contact Alumex at info@alumexgroup.com
