This glass extension in Oxfordshire was designed and installed by IQ Glass as part of the remodelling of a home in Wallingford. Working with MarbleAir Architects and Dawes Developments, IQ Glass delivered a glazing package combining a biparting slim sliding door system, frameless structural glass walls and a fixed rooflight set within the solid roof. The extension creates a new open-plan kitchen and snug with a stronger connection to the patio, using solar control glass, heat soak tested panes and carefully aligned framing to maintain clear garden views.
Project Partners
Architect: MarbleAir Architects
Contractor: Dawes Development
Image credits: Alexandra Davies Photography
Location
Oxfordshire
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Glass extension in Oxfordshire with globally aligned structural glazing
The design challenge was to create a compact rear addition that would significantly improve the flow of the house and its relationship with the garden. Although the extension has a modest footprint of roughly 5m by 4m, the glazing had to make the new kitchen and snug feel larger, brighter and more connected to the patio.
The extension uses a cantilevered flat roof with structural posts at the front corners, so the glazing layout needed to be coordinated with the roof structure rather than treated as a standard infill. The structural glass and sliding doors were set out so that the slim aluminium profiles align with the structural posts, reducing visual interruption across the garden elevation.
The project also required a balance between openness and comfort. Large glass walls and a fixed rooflight were needed to bring daylight into the remodelled interior, while solar control coatings and heat soak testing were included across the glazing package to support long-term performance.
Biparting sliding doors for a clear patio connection
The front elevation uses a two-track biparting sliding door system measuring 4030mm wide by 2760mm high. This configuration allows the moving panes to open from the centre, creating a direct route from the kitchen and snug to the patio while maintaining a symmetrical glazed elevation when closed.
The sliding doors were finished in RAL 7016 Matt to coordinate with the wider glazing package. An integrated slot drain was included at the threshold to manage water at the door line while allowing the transition to the external patio to remain visually minimal.
By aligning the sliding door sightlines with the structural posts of the cantilevered roof, the glazing avoids adding unnecessary visual obstruction to the garden-facing elevation.
Frameless glass walls and fixed rooflight for daylight
Frameless structural glass panels form the side elevations of the extension, creating a glass box effect around the new living space. The silicone-jointed glass panels allow the walls to remain visually light, while the concealed fixing system reduces the amount of visible framing at key junctions.
A fixed rooflight measuring 2250mm by 1300mm was positioned in the centre of the solid roof. This brings daylight down into the open-plan space from above, supplementing the side and front glazing and reducing the reliance on the patio-facing elevation alone.
Together, the structural glass walls and rooflight make the extension feel larger than its footprint while maintaining a disciplined relationship between glass, roof structure and internal layout.
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Performance considerations
Performance for this glass extension in Oxfordshire was driven by solar gain, large-pane durability, water management and installation accuracy. Solar control coatings were specified across the glazing package to manage glare and heat gain within the highly glazed extension, while all glazing was heat soak tested to reduce the risk of nickel sulphide failure in the toughened panes.
The sliding door threshold was detailed with an integrated slot drain, helping to manage surface water at the patio interface without introducing a visually heavy drainage channel. The RAL 7016 Matt finish provides a consistent external appearance across the door system and adjacent structural glazing.
The frameless glass walls, biparting sliding doors and rooflight required careful setting out to maintain alignment with the cantilevered roof and structural posts. Towers, lifting equipment and HIAB delivery were allowed for within the installation strategy, supporting safe handling and accurate placement of the larger glass elements.
Technical details
- Slim framed sliding doors: two-track biparting system measuring 4030mm W × 2760mm H, finished in RAL 7016 Matt; 20mm vertical junction sightline; panes up to 2500mm W × 3000mm H and 320kg; Uw 1.3 W/m²K; air Class 4 / water Class 7A / wind Class C5; acoustic reduction up to 41dB
- Threshold and drainage: integrated slot drain specified to the sliding door line; sliding system includes a 110mm integrated subframe drainage profile across the track
- Frameless structural glazing: silicone-jointed structural glass walls, with project elevations recorded at 5050mm × 2760mm and 4045mm × 2760mm; thermally broken fixing profile depth 63mm; max glass thickness 41.5mm; expected Uw 1.1 W/m²K; minimum fixing setback 55mm; structure deflection allowance 5mm
- Fixed rooflight: single-pane rooflight measuring 2250mm × 1300mm; structural roof glazing supports glass thickness up to 37.5mm DGU; typical Ug 1.1 W/m²K; example Uw 1.2 W/m²K; minimum upstand 150mm
- Glass specification and handling: solar control glass and heat soak testing specified to all glazing; towers, lifting equipment and HIAB delivery allowed for installation
Wallingford shows how a glass extension in Oxfordshire can use structural glass, roof glazing and slim sliding doors to make a compact rear addition feel open, bright and closely connected to the garden. This approach is suited to architects and specifiers working on contemporary rear extensions where large glass elevations, solar control, threshold drainage and careful alignment with roof structure must be resolved as one architectural glazing package.
To discuss a similar glass extension in Oxfordshire, contact IQ Glass for technical advice on frameless structural glazing, slim sliding door configurations, fixed rooflights and solar control specification.
