Chester Street

Three Storey Extension with Sliding Glass Doors & Juliette Balconies

A Glass Infill Extension in Belgravia for a Grade II Listed Townhouse 

Chester Street is a sensitive refurbishment and extension of a six‑storey Grade II listed townhouse located in the Belgravia Conservation Area. Designed by Found Associates, the project involved the removal of poor quality historic additions and the creation of a contemporary rear intervention, including a three‑storey glass infill extension in Belgravia. 

IQ Glass was appointed to design, supply and install the architectural glazing for the full height rear façade, delivering a consistent system of slim framed sliding glass doors across three levels to maximise light, openness and connection to the external space. 

Products Used

Location

London
a three storey glass extension in London with sliding glass doors and metal cladding
Juliet balcony doors - IQ Glass - Chester Street
a minimal Juliet balcony design as part of a three storey courtyard extension in London
Juliet balcony doors - IQ Glass - Chester Street

Design Context and Heritage Constraints 

Working within one of London’s most tightly controlled conservation environments required a precise balance between preservation and contemporary design. The existing townhouse retained significant heritage value, meaning all new interventions had to be clearly distinguishable while remaining respectful of the original architecture. 

The rear extension spans the full width between neighbouring party walls, forming a compact infill condition typical of Belgravia properties. The architectural intent was to introduce a lightweight, modern façade that would contrast with the historic structure while maintaining visual cohesion across multiple storeys. 

A key challenge was achieving full height glazing to each level without compromising safety or the uniform appearance of the façade. Upper floors required fall protection, yet the design demanded that each elevation read identically to maintain architectural clarity. 

Multi‑Storey Glazed Façade Using Slim Sliding Doors 

IQ Glass designed and installed a series of slim framed sliding doors to each level of the extension, forming a continuous glazed elevation across three storeys. Each opening measures approximately 3.4 metres wide by 2.5 metres high and is configured as a three panel, three track system with two sliding panels and one fixed pane. 

This repetition of glazing across all floors creates a strong vertical rhythm and reinforces the architectural concept of a cohesive glass infill structure. The use of minimal framing allows the glazing to sit quietly within the façade, ensuring the extension reads as a refined contemporary addition rather than a dominant intervention. 

The sliding doors enable large opening sections at each level, improving natural ventilation and allowing internal spaces to connect directly with the exterior. In a dense urban context such as Belgravia, this level of openness is critical to enhancing spatial quality within the townhouse. 

Integrating Safety Without Compromising Design 

To address the need for fall protection on the upper levels, IQ Glass developed an integrated solution using frameless glass balustrades fixed within the sliding door framework. This approach allows the first and second floor openings to function as Juliet balconies while maintaining the clean, uninterrupted aesthetic of the façade. 

By incorporating the balustrade into the door system itself, the design avoids the need for secondary railings or visible barriers. This ensures that all three storeys retain a consistent visual language, preserving the architectural integrity of the glass infill extension in Belgravia. 

The glazing is complemented by aluminium pressings installed between floor levels and along the outer edges of the façade. These elements are colour matched to the sliding door frames, creating a seamless finish that unifies the extension as a single architectural composition. 

a glass Juliet balcony design as part of a large three storey glass extension in London
a sliding glass door with integrated balustrade to create a frameless Juliet balcony in London

Additional Notes: Urban Living and Spatial Value 

The introduction of full height glazing across multiple storeys significantly enhances the usability and experience of the internal spaces. By maximising daylight and providing strong visual connections to the exterior, the extension transforms previously constrained areas into light‑filled living environments. 

In high‑value residential locations such as Belgravia, architectural interventions that increase openness, improve internal layout and introduce contemporary detailing can have a measurable impact on both liveability and long‑term property value. The use of glazing as a primary façade element is central to achieving this outcome. 

Technical Details 

  • Three sets of slim framed sliding glass doors installed across three storeys of a rear extension 
  • Each doorset configured as three panel, three track system with two sliding panels and one fixed pane 
  • Each opening measuring approximately 3.4m wide x 2.5m tall 
  • Integrated frameless glass balustrades to first and second floor sliding doors to create Juliet balcony configuration 
  • Balustrades fixed within door frame to maintain flush, uninterrupted façade design 
  • Aluminium pressings installed between floors and to the sides of the glazing to conceal structure and unify the elevation 
  • All framing and pressings finished in bronze anodised finish (E6/C34) 
  • Glazing designed as full height façade across a three‑storey glass infill extension in Belgravia 

Begin Your Glass Infill Extension in Belgravia Project 

For architects, developers and private clients working on high‑end London townhouses, Chester Street demonstrates how a glass infill extension in Belgravia can transform internal spaces while respecting heritage context and planning constraints. IQ Glass provides specialist glazing design, engineering and installation support for complex residential projects across conservation areas and listed buildings. Contact our team to discuss your project requirements. 

Associated Products

Frameless Glass Balustrades

Frameless glass balustrades for internal and external projects to create a clear yet strong safety barrier.
Glass Juliet balcony

Glass Juliet Balconies

Using minimal glass systems to create Juliet Balconies in a variety of designs.

luxury new build home with minimal glass facade

Slim Framed Sliding Glass Doors

Sliding doors with ultra-slim sightlines, offering only the highest levels of performance and durability.
Aluminium Pressings

Aluminium Pressings and Flashings

Aluminium pressings and flashings offer durability, corrosion resistance, and flexibility in design and application, making them popular choices for various different project specifications.

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