London based Studio McW has extended and redesigned the lower ground floor of Threshold House, a semi-detached, split-level Victorian house in the Islington district of London. The project reconfigures the previously constrained lower level to support both everyday living and larger social gatherings, while strengthening the relationship between interior spaces and the rear garden.

The upper levels of the house had been previously renovated. The rehabilitation and extension of the lower ground floor called for a layout that creates a sense of arrival when descending from the upper ground floor, allows for flexibility, and opens gradually towards the garden and its two mature, protected palm trees.

Brief and spatial strategy

The clients requested a highly functional layout that could support entertaining while retaining quieter, more private areas. In response, Studio McW organised the lower ground floor around a sequence of interconnected rooms, allowing social spaces to expand when needed while maintaining separation from more private functions.

One existing room was retained as a flexible space, able to serve as a study or guest bedroom. This requirement informed the placement of a centrally located bathroom and the development of multiple circulation routes, enabling the floor to adapt to different patterns of use without reconfiguration.

Extension and external form

The extension reaches the maximum footprint permitted by planning restrictions and accommodates a kitchen–dining area with an adjoining living room, a utility room, a dual-access bathroom, and the study or spare bedroom.

The external composition is organised as two complementary elevations connected by a thick brick wall. This approach maintains visual depth and balances the proportions of the original Victorian house. The left-hand elevation addresses the primary social spaces, while the right-hand elevation corresponds to the more private rooms.

The larger brick volume frames the kitchen–dining area and aligns views through to the living room beyond. Tiered brickwork projects from full-height Crittall-style doors, creating depth and articulating the extension’s mass. To the right, the composition aligns with the existing outrigger above and introduces a contrasting moss-green steel framework, colour-matched to the metal doors.

Originally conceived as a fully brick elevation, the metal elements were introduced to moderate the perceived scale of the extension when viewed from the garden and to allow for a potential future upper-ground-floor addition. The steel framework projects to the same depth as the brickwork and incorporates recessed windows with sliding openings. Externally, these align with a brick bench; internally, they correspond to a built-in seat within the study.

A crossed steel detail extends over the sliding window, allowing it to remain open while providing shelter from rain. A low-maintenance green roof further reduces the visual impact of the extension when viewed from the upper-ground-floor reception rooms.

Internal layout and circulation

From the upper ground floor, stairs descend directly into the kitchen–dining area. A large rooflight positioned above the dining table brings daylight into the centre of the plan, filtered through exposed timber beams. The living room sits at the front of the house, partially below street level, and is accessed through two enlarged openings from the kitchen. These maintain visual and spatial continuity between the main living spaces while allowing a degree of separation.

The kitchen forms the centre of the plan and anchors a circular route connecting the social areas to the study, utility room, and bathroom. A sliding pocket door between the study and dining area, together with dual access to the bathroom, supports fluid movement through the floor, particularly when hosting larger groups of guests.

The bathroom was designed to function both as an ensuite for the study when used as a guest bedroom and as a shared facility during social events. When the doors are left open, daylight from the utility room and study is drawn into the centre of the plan, increasing the sense of openness.

Environmental considerations

Material and construction decisions were informed by environmental considerations. Existing building fabric was retained where possible and the extension footprint was limited, reducing the quantity of new material and allowing shorter structural spans. Durable materials such as brick and metal were used throughout, alongside a fabric-first approach prioritising thermal performance, reduced finishes, and passive measures. An extensive sedum green roof provides thermal moderation and rainwater attenuation while protecting the waterproofing membrane. Exposed structural elements and a limited material palette support ease of repair and the layout remains flexible to accommodate changing household needs over time.

Spatial resolution

The completed lower ground floor reorganises a complex set of requirements into a clear and adaptable plan. Through the considered arrangement of rooms, calibrated circulation, and a restrained material palette, the project supports both everyday use and periodic transformation. The extension establishes a stronger connection to the garden while allowing the lower level to operate as the social and functional centre of the house.

Greg Walton, Director, Studio McW said:

“Our clients wanted the lower ground floor to support everyday use while accommodating larger gatherings, with a sense of surprise as the space opens towards the garden.”