Structural Glazing

A Guide to Corner Glass Windows

What is a Glass to Glass Corner Window? 

A glass to glass corner window is a frameless glazing detail where two panes of glass are joined directly together at a corner without a visible corner post. 

The connection is created using structural glazing silicone and stepped glass units, resulting in a transparent corner with uninterrupted views and maximum daylight ingress. By removing the visual obstruction of a traditional frame or mullion, glass to glass corners create a stronger connection between internal and external spaces. 

Glass to glass corner glazing is commonly used in: 

• Contemporary new build homes 

• Luxury house extensions 

• Glass box extensions 

• Oriel windows 

• Structural glass walls 

• Commercial buildings 

• Hotels and hospitality projects 

The result is one of the most striking architectural glazing details available, creating the appearance that the corner of the building has disappeared entirely. 

Real Project Example: Scorrybreac Road 

A frameless glass corner window was used at Scorrybreac Road to maximise views across the surrounding landscape. Two structural glass elevations were joined framelessly, without a corner post or any frame, allowing uninterrupted views around the corner of the property. 

Why Use a Glass to Glass Corner? 

The popularity of glass to glass corners has grown rapidly because they solve both aesthetic and functional design challenges. 

Increased Natural Light 

Traditional building corners block daylight from one direction. Removing the corner post allows sunlight to enter from two elevations simultaneously, creating brighter interior spaces throughout the day. 

Uninterrupted Views 

By eliminating visible corner framing, views continue around the corner of the building without interruption. This is particularly valuable for projects with gardens, countryside views or coastal settings. 

Contemporary Appearance 

A frameless glass corner creates a minimalist architectural aesthetic that works equally well in contemporary homes, luxury extensions and heritage projects where a modern intervention is required. 

Stronger Connection to the Outdoors 

Many architects use glass to glass corners to blur the distinction between inside and outside, helping internal living spaces feel larger and more connected to the landscape. 

How Does a Glass to Glass Corner Work? 

A glass to glass corner is created by joining two insulated glass units together using high-performance structural glazing silicone. 

Typically, the corner glass units are manufactured with stepped edges that allow the glass panes to overlap neatly at the corner. Once installed, the structural silicone provides: 

• Weather resistance 

• Structural stability 

• Accommodation for thermal movement

• Air tightness 

• Long-term durability 

From both inside and outside, only a neat silicone joint remains visible. 

The appearance is often referred to as a frameless corner, invisible corner or structural glass corner. 

How are Glass-to-Glass Corners Supported? 

One of the most common misconceptions about glass-to-glass corners is that the glass itself supports the building above. 

 In reality, a glass-to-glass corner is usually a non-loadbearing glazing detail. The structural loads from the roof, upper floors or façade must be transferred around the corner opening through an independent support structure. 

The support method will vary depending on the size of the glazing, the building design and the structural requirements of the project. Common solutions include: 

• Concealed steel goalposts 

• Structural steel frames 

• Reinforced concrete structures 

• Structural glass beams 

• Structural glass fins 

• Cantilevered support systems 

The goal is always to create the appearance of a frameless glass corner while ensuring that all structural loads are safely carried by the surrounding building structure. 

For this reason, glass-to-glass corners perform best when considered early in the architectural design process, allowing the glazing designer and structural engineer to coordinate support requirements from the outset. 

Real Project Example: Ladlecombe, Cotswolds  

At the Cotswolds Contemporary Refurbishment project, the design team wanted to create a completely frameless glass corner at the end of a dramatic open-plan living space. The glazing comprises a 22.5m-long structural glass wall with a 4.7m return elevation, joined at a frameless 90-degree glass-to-glass corner. 

To achieve this, the architect designed the roof structure as a substantial cantilever anchored back into the surrounding hillside landscape. By transferring the structural loads away from the corner, the need for a supporting post was eliminated entirely. This allowed IQ Glass to create a fully transparent glass corner with uninterrupted views across the landscape, giving the glazing an almost gravity-defying appearance while maintaining the structural integrity of the building. 

This project demonstrates how successful glass-to-glass corner design relies on close collaboration between the architect, structural engineer and glazing specialist from the earliest stages of the project, ensuring that the building structure supports the architectural vision rather than constraining it. 

Glass to Glass Corner vs Corner Window with Mullion 

There are two primary ways to create glazing around a building corner. 

Corner Window with Mullion 

A conventional corner window uses two separate glazed units connected by a visible post or frame. 

Advantages: 

• Easier structural design 

• Opening windows can often be incorporated 

• Lower cost 

Disadvantages: 

• Interrupted views 

• Reduced light transmission 

• More visible framing 

Glass to Glass Corner 

A frameless corner removes the visible post entirely. 

Advantages: 

• Uninterrupted views 

• More natural light 

• Minimal appearance 

• Greater architectural impact 

Disadvantages: 

• More complex structural requirements 

• Higher specification glazing 

• Requires coordination with structural design 

Can a Glass-to-Glass Corner Open? 

A glass to glass corner does not have to be fixed. 

Many projects use slim framed sliding glass doors to create opening corners. 

In an open corner sliding door arrangement, both sliding elevations move away from the corner without any permanent corner post remaining in place. When fully opened, this creates a completely open corner. 

Opening glass corners are particularly popular for: 

• Kitchen extensions 

• Open-plan living areas 

• Garden rooms 

• Luxury new-build homes 

• Hospitality projects 

Combined with flush thresholds, these systems create a seamless transition between inside and outside spaces. 

Real Project Example: Killieser Avenue  

At Killieser Avenue, a pair of open-corner sliding glass doors were used to create a fully opening glass-to-glass corner between the internal living space and the garden. When closed, the slim framed sliding doors meet neatly at the corner, maintaining uninterrupted views and maximising natural light. When opened, both elevations slide away from the corner, completely removing the boundary between inside and outside. This creates a large open corner without a fixed corner post, allowing the terrace and living area to function as a single connected space and demonstrating how glass-to-glass corners can be both visually minimal and fully operable. 

Glass to Glass Corners with Structural Glazing 

The most minimal glass corner designs use structural glazing. 

Structural glazing allows all fixing systems to be hidden within surrounding building finishes, leaving only glass visible on the external face of the building. 

Using systems such as Invisio Structural Glazing, architects can create: 

• Fixed glass corners 

• Floor-to-ceiling glazing 

• Structural glass walls

• Glass box extensions

• Oriel windows

• Frameless links

This results in a highly contemporary appearance while maintaining modern thermal and weather performance requirements. 

Thermal Performance of Glass to Glass Corners 

Modern glass to glass corners can achieve thermal performance comparable with other high-performance glazing systems. 

Performance can be enhanced through: 

• Triple glazing 

• Low-emissivity coatings

• Warm edge spacer technology 

• Solar control glazing 

• Thermally broken fixing systems

• Acoustic laminated glass 

For projects with demanding performance requirements, glazing specifications can be tailored to suit Passive House, low-energy and highly insulated building designs. 

How Large Can a Glass to Glass Corner Be? 

Maximum sizes depend on: 

• Glass specification 

• Wind loads 

• Structural support 

• Glass weight 

• Building geometry 

Because every project is engineered individually, there is no single maximum size. 

Glass to glass corners can range from: 

• Small corner windows 

• Bay and Oriel windows 

• Floor-to-ceiling residential glazing 

• Double height glass walls 

• Multi-storey structural glass installations 

The most appropriate specification is developed through collaboration between the architect, structural engineer and glazing designer. 

Can Glass-to-Glass Corners Be Used in Extensions? 

Glass to glass corners are particularly popular within extension projects because they allow multiple elevations to be glazed without heavy framing. 

Applications include: 

• Kitchen extensions 

• Dining room extensions 

• Side return extensions 

• Wraparound extensions 

• Glass box extensions 

• Listed building additions 

In heritage projects, glass corners can help create a clear distinction between the original building and the new intervention while preserving views of the historic structure. 

Real Project Example: Made of Sand 

In Devon, a contemporary extension was designed around a frameless glass-to-glass corner to maximise views of the surrounding coastal landscape and strengthen the connection between the interior and exterior spaces. By removing the need for a visible corner post, the glazing wraps seamlessly around the corner of the extension, allowing natural light to enter from two directions and creating uninterrupted views along the coastline. The project demonstrates how a glass-to-glass corner can be successfully incorporated into an extension design, transforming what would traditionally be a solid building corner into a defining architectural feature that enhances both the experience and appearance of the space. 

Glass to Glass Corners for Oriel and Bay Windows 

Glass to glass connections are also used to create projecting glazed features such as Oriel windows and contemporary bay windows. 

These designs use structural glazing to form multiple glass-to-glass connections, creating a fully glazed projection that extends beyond the building line. 

The result is a dramatic architectural feature that increases daylight and creates unique internal spaces such as seating areas, reading nooks or viewing spaces. 

Real Project Example: Park Road 

The Park Road project uses frameless glass bay windows to create contemporary projections from the façade. Glass-to-glass corner connections allow daylight to enter from multiple directions whilst maintaining a minimal appearance. 

 

Glass-to-Glass Corner Case Studies 

Glass-to-glass corners can be incorporated into a wide range of architectural projects, from contemporary extensions and luxury new-build homes to heritage renovations and structural glass box windows. Explore our collection of corner window case studies to see how architects across the UK have used frameless corner glazing to maximise light, views and connections to the landscape. 

View Corner Window Projects 

 

Designing a Glass to Glass Corner Window 

Glass-to-glass corners are one of the most impressive features in contemporary architecture, but achieving a truly frameless result requires careful coordination between the architect, structural engineer and glazing specialist from the earliest stages of design. 

Key considerations include: 

• Structural support requirements 

• Thermal performance targets 

• Solar control strategies 

• Drainage design 

• Opening and ventilation requirements 

• Wind load performance 

• Building regulations compliance 

The earlier a glass-to-glass corner is incorporated into the design process, the greater the flexibility available in terms of size, appearance and performance. 

Whether you are designing a contemporary extension, luxury new-build home or highly bespoke architectural feature, the IQ Glass team can help develop the glazing specification from the earliest concept stage. Our specialists can provide project-specific advice on structural design, performance requirements, detailing, budgeting and system selection, as well as share relevant case studies and technical details from similar completed projects. 

Speak to our team about your glass-to-glass corner design to discuss specification advice, project examples and technical guidance tailored to your scheme.