Structural Glazing and Curtain Walls: A Guide for Builders and Architects

Structural glazing and curtain wall systems define the skylines of modern Indian cities. From the glass towers of BKC in Mumbai to the IT parks of Bangalore and Kochi, these aluminium-and-glass facades create iconic buildings that are as functional as they are beautiful.

What Is Structural Glazing?

Structural glazing is a technique where glass panels are bonded to an aluminium framework using high-strength structural silicone sealant, rather than being held by mechanical clips or pressure plates. The result is a smooth, flush glass exterior with no visible framing on the outside.

What Is a Curtain Wall?

A curtain wall is a non-structural exterior wall system — typically made of aluminium frames and glass — that is attached to the building's structural frame. It doesn't carry any building load; it only supports its own weight and transfers wind loads to the main structure.

Types of Curtain Wall Systems

1. Stick System (Conventional) Individual aluminium mullions (vertical) and transoms (horizontal) are assembled on-site, and glass panels are glazed into the framework piece by piece.

Pros: Lower material cost, easier to transport, flexible for complex geometries Cons: Slower installation, more on-site labour, higher risk of workmanship variation

Best for: Low-rise to mid-rise buildings, buildings with irregular facades

2. Unitized System Complete curtain wall units (aluminium frame + glass) are pre-fabricated in the factory and shipped as ready-to-install modules. They interlock on-site like a puzzle.

Pros: Faster installation (critical for high-rises), better quality control, reduced on-site labour Cons: Higher upfront cost, requires precise structural tolerances, larger transport logistics

Best for: High-rise buildings, projects with tight timelines, large-scale commercial developments

3. Spider Glazing (Point-Fixed) Glass panels are secured at discrete points using stainless steel spider fittings or bolted connections. No aluminium framing is visible — only the glass and its point fixings.

Pros: Maximum transparency, dramatic architectural impact, allows very large glass panels Cons: Most expensive system, requires structural glass calculations, limited thermal performance

Best for: Atriums, lobby entrances, exhibition centres, premium facades

4. Semi-Structural Glazing A hybrid approach where the glass is partially bonded with structural silicone and partially held by mechanical retention (aluminium pressure plates). Offers a near-flush exterior at a lower cost than full structural glazing.

Best for: Mid-range commercial buildings wanting a structural glazing look without the full premium cost

Aluminium Framework: The Hidden Backbone

While glass gets the visual attention, the aluminium framework is what makes curtain walls possible:

Mullion and Transom Design - **Standard profiles:** 50mm to 65mm wide aluminium extrusions for most applications - **Thermally broken profiles:** Polyamide strips between inner and outer aluminium faces reduce heat conduction by up to 60% - **Structural calculations:** Mullion sizes are engineered based on wind load, panel weight, and span between anchor points

Surface Treatment - **Powder coating:** AAMA 2604 or 2605 standards for architectural applications - **Anodizing:** Provides a hard, corrosion-resistant finish - **PVDF coating:** Superior UV and chemical resistance for coastal and high-pollution areas

Drainage and Ventilation Every curtain wall system includes concealed drainage channels within the aluminium profiles to manage water infiltration. Pressure equalization chambers prevent water from being driven inward by wind pressure.

Glass Options for Curtain Walls

Performance Requirements

Thermal Performance In India's hot climate, curtain wall thermal performance is critical for energy efficiency. Key metrics: - **U-value:** Target below 2.5 W/m²K (lower is better) - **SHGC (Solar Heat Gain Coefficient):** Target 0.25-0.40 for tropical climates - **VLT (Visible Light Transmittance):** Balance between daylight and solar control

Wind Load Resistance Curtain walls must withstand design wind pressures specific to the building's height, location, and terrain category (as per IS 875 Part 3). Typical design pressures range from 1.0 kPa for low-rise buildings to 3.0+ kPa for high-rise coastal towers.

Water Tightness Systems are tested to resist water infiltration under static and dynamic pressure conditions, simulating heavy monsoon rains with wind-driven water.

Cost of Structural Glazing in India

*Costs include aluminium framework, glass, sealants, and installation.*

Why Choose Hennovate for Structural Glazing?

Hennovate Pvt Ltd brings engineering precision and fabrication excellence to every structural glazing project. Our capabilities include:

• Structural engineering support — Wind load and glass thickness calculations
• In-house aluminium fabrication — CNC-cut mullions and transoms for perfect fit
• Certified installation teams — Trained in structural silicone application and curtain wall assembly
• Quality testing — Water spray tests and pull-out tests on completed installations
• After-sales support — Sealant inspection, glass replacement, and system maintenance

Planning a commercial glass facade? Contact us for a technical consultation and project estimate.