Located in Tunbridge Wells, UK, the Collingwood project demonstrates how high-performance architectural glazing can transform a conventional residential extension into a striking contemporary living space. IQ Glass was appointed to design, supply and install a complete glazing package for a bespoke glass box extension, delivering a structure defined by transparency, daylight and precision engineering.
The extension features two sets of ultra-slim sliding glass doors forming the primary glazed elevations. A frameless structural glass roof spans approximately 9.5 metres by 4.6 metres, supported by structural glass beams that maintain open sightlines while providing the necessary structural support. Silicone-jointed glazing and concealed support elements help create the appearance of a seamless glass volume.
Vision and Ambition
The client's ambition was to create a modern addition that would contrast with the existing house while maintaining a strong architectural relationship with the original building. The design centred around a fully glazed extension that would appear lightweight and almost invisible, maximising uninterrupted views of the garden and flooding the interior with natural light.
To achieve this architectural vision, IQ Glass specified a combination of slim framed sliding glass doors, frameless structural glazing and bespoke structural glass beams. The result is a refined glass enclosure that blurs the boundary between inside and outside, creating a bright dining and living area that remains connected to the landscape throughout the year.
Structural Glass Roof Coordinated With Sliding Elevation
A defining feature of the Collingwood extension is the seamless integration between the frameless structural glass roof and the slim framed sliding door elevations. Rather than treating the roof and vertical glazing as separate elements, IQ Glass engineered the entire enclosure as a coordinated glazing system, creating a continuous architectural form with minimal visual interruption.
Careful coordination between the roof and sliding door systems allowed support elements and junction details to be concealed wherever possible. Structural glass beams carry loads across the roof while preserving the minimal aesthetic, creating the appearance of a floating glazed canopy above the living space. The precise alignment of glazing lines and framing profiles ensures a clean and unified architectural expression from every angle.
Sliding Doors With Integrated Slot Drainage
The sliding elevations at Collingwood were designed to deliver the highest levels of transparency while maintaining the practical performance required for everyday residential use. IQ Glass installed slim framed sliding glass doors with exceptionally narrow sightlines, creating expansive glazed openings that maximise views and natural light while allowing the architecture to take centre stage.
The flush threshold detailing enhances accessibility and creates a seamless transition to the outdoor terrace, while concealed drainage infrastructure ensures long-term performance without compromising the visual simplicity of the glazing installation. Combined with the ultra-slim framing and large glass panels, the result is an elegant sliding door solution that balances refined aesthetics, functionality and durabilitity.
Key Challenges
A key challenge of the project was balancing extreme transparency with structural performance and thermal efficiency. Large-format glazing panels required careful engineering to minimise visible framework while maintaining stability and compliance with modern building regulations. Equally important was the integration of clean junctions between the glazing systems, roof structure and existing building fabric, ensuring every detail contributed to the minimalist aesthetic.
Technical Details
- Glass box extension formed using slim framed sliding doors and frameless structural glazing to create a minimal glass enclosure.
- Two sets of slim framed sliding glass doors form the primary glazed elevations of the extension.
- Front elevation incorporates a two-track, four-panel slim sliding door system in a bi-parting configuration, measuring approximately 9.4m wide x 2.6m high.
-Side elevation incorporates a two-track, two-panel sliding door system with one fixed pane and one sliding panel, measuring approximately 2.7m wide x 2.6m high.
-Frameless structural glass roof measuring approximately 9.5m wide x 4.6m deep with a 5° fall.
-Roof constructed from four structural glass panes connected with structural silicone joints and supported by bespoke glass beams.
-Double-glazed roof specification comprising a 10mm toughened outer pane and laminated 2 x 6mm inner pane.
-Solar control coating achieving approximately 70% light transmission with a g-value of 0.35.
-Structural glass beams manufactured from multiple layers of laminated low-iron glass.
-Structural steel support beam above the sliding doors clad with 3mm bespoke insulated aluminium pressings.
-All aluminium framing and pressings finished in PPC RAL 7016 Anthracite Grey.
