In Covent Garden, a listed building gets a bold new rooftop silhouette

Can you briefly describe the project Carmody Groarke took on?

It's a new duplex penthouse apartment in a 19^th-century Grade II-listed merchant’s house, with a rooftop aluminium pavilion. The top two floors of the existing building have been extensively renovated and remodelled to accommodate bespoke patterns of family life.

On the lower level, the entrance lobby and bedrooms are lined throughout with walnut-panelled joinery to give a warm and welcoming atmosphere. In contrast, the upper floor’s generous open-plan living takes full advantage of the loft space’s high ceilings and panoramic views over Covent Garden Market.

Who is the project for and what was the brief?

The project is for a private client’s permanent family home in central London. Working within the constraints of a challenging historic site, the brief was to reimagine the existing building and create a spacious, light-filled house with more fresh air and seamless functionality, tailored to their lifestyle.

An essential aspect of the brief was increasing the interior space and creating an outdoor area. The aluminium pavilion offers a retreat from the busy city below and is somewhere the family can relax and enjoy the views of the surrounding cityscape.

The client also expressed a desire to modernise the building's services, improving the overall thermal performance and airtightness of the home.

Were there any significant factors that influenced the design?

The design was significantly influenced by its historically sensitive location and the Grade II-listed status of the building, which was originally constructed in 1877 as a linen draper’s shop. Given the strict heritage constraints, its overall massing could not be altered, requiring a more unconventional and delicate approach to improving functionality and maximising usable space.

To bring air and light into a deep-plan loft, the design has an upside-down layout with living spaces upstairs and bedrooms downstairs.

Can you explain the external treatment of the project?

The new 14m rooftop pavilion is made of 25mm-thick solid-plate sanded aluminium blades, using the fewest possible components. Where fixings are necessary, a concealed and highly engineered countersunk solution ensures structural rigidity while maintaining a seamless appearance. All angled connections are mitred for precise and flat connections. Aluminium was chosen for its physical lightness and ability to create a sense of visual levity.

Its monolithic sheet metal plates are made to appear to lean against one another in a state of structural equilibrium, where they achieve perfect balance. This gives the pavilion a distinctive, elemental presence – a bold new silhouette on the city skyline that contrasts with the surrounding roof extensions.

Can you explain how the interiors have been designed?

Choices were guided by the character of the historic building and crafted in collaboration with a team of makers and craftspeople. Materials include black American walnut, heartwood ash, and Italian silver travertine handpicked from quarried blocks. Each stone slab was dry-laid and selected to define key areas such as the kitchen, bathrooms, and terraces. The travertine creates a striking contrast with the seamless aluminium while harmonising with the rich tones of the walnut. 

Inside the new kitchen, crafted from sanded stainless steel, a material dialogue is established with the aluminium exterior.

What has been the project’s approach to sustainability?

The project preserves the existing Grade II-listed building, ensuring its historical character is maintained while significantly improving its functionality and energy performance.

The pavilion exemplifies a circular design approach, constructed using a bolted assembly method that facilitates full deconstruction and recyclability. Left in its raw material state without additional finishes, the pavilion’s aluminium structure was selected for its lightweight properties, enabling the use of a timber support system and reducing the overall environmental impact.

Can you describe the main challenge and how you overcame it?

Working within a highly constrained site in busy Covent Garden, with shared tenancies and limited access to the building, demanded meticulous planning and coordination to minimise disruption to neighbouring properties. Navigating these constraints required innovative design solutions throughout the construction process.

Equally crucial was the collaboration with skilled craftspeople and manufacturers, whose expertise enabled bespoke solutions ultimately unlocked the full potential of the design.

What is your favourite moment in the project? 

One of my favourite elements of the project is how the pavilion serves as a transition between old and new. Its aluminium structure stands in contrast to the historic fabric of the building, highlighting the dialogue between past and present. This contrast is further reinforced by its function as a sheltered terrace – an in-between space where you are outside without being fully exposed. Open to the elements yet offering protection, the pavilion creates an experience of being immersed in Covent Garden while maintaining a sense of enclosure.

Are there lessons from this project which might be applied elsewhere?

The project highlighted the importance of learning from the existing building itself. The success of the pavilion as a piece of architectural engineering was only possible through close collaboration with the expert engineers and craftspeople at Price & Myers and Littlehampton Welding/Format.

Additionally, the project emphasised the value of working closely with planners to sensitively restore and revitalise culturally significant buildings in central London. This approach shows how a well-informed and respectful design process can enhance the historic fabric of a building while ensuring it remains functional and relevant for modern use.

Ana Ferreira is associate at Carmody Groarke 

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Key data:

Total contract cost Confidential 
Area of extension 450m²