Brook House, Sussex

Usonian Remodelling of a Sussex Home

Background

We were approached to complete a remodelling, retrofit and extension of a family home in Wisborough Green, West Sussex. The client wanted the design to be in line with the Usonian principles of American Midwestern architecture.

Originally constructed in the 1960s, with alterations as recent as 2011, the building was ill-equipped to address the climate emergency. A principal driver for the design was the need to improve the thermal and airtightness performance throughout by adopting a ‘fabric-first’ approach.

Client:
Private Client
Status
On site, due to complete in 2026
Approach

Our primary ambition was to create a healthy and low-energy home through a combination of remodelling, extension and fabric upgrades.

We carried out extensive testing to develop the preferred design, which seeks to retain as much of the existing fabric as possible to limit the heavy carbon cost of demolition. We have reconfigured the house to provide additional living space and create a stronger relationship with nature, in a design language appropriate to the wider local area.

External materials are largely applied over additional insulation, with a simple palette of breathable render and timber weatherboard cladding to each facade.

Ground floor windows are to be framed with a rhythm of verticals creating elegantly proportioned openings that allow the sunlight to stream in. At first-floor level, existing uPVC windows are replaced with slim-profile aluminium framed windows with an improved U-value performance.

The existing flat roof above the entrance porch and garage is to be retained, insulated and extended, offering protection from the summer sun while letting winter light flood the interior. This logic is continued to the rear extension, with a reduced canopy overhang given the building’s orientation.

Proposed new mono-pitched roofs at second floor level oversail to provide some further shade, and are finished in a slate tile with in-line PV array to generate electricity onsite and help combat the known inconsistency of supply in the area.

Outcome

Our designs unify a confused collage of a building into a coherent architectural whole, marrying inspiration from the original form and treatment with the client’s desire for Usonian design and significant improvements to energy performance.

As the elevations show, the design recalls the original form of the building without compromising internal living space created by previous extensions. Material expression recalls the banding widely seen in the local area, allowing the building to make a positive contribution to the wider streetscape.

The roofline has been reconsidered to give visual priority to the main body of the house with the side extension clearly secondary. This improves the perceived balance and reduces the sheerness of the facade on approach.

The majority of first-floor window openings are retained, with new fenestration below designed to better relate to these, unifying the composition.

Internally, we adjusted the entrance sequence for a more generous arrival, introducing long views from front to back. The garage has been converted to become a space for home-working, while a rear extension provides dining and family space with improved connection to the garden. Adjustments to the utility spaces offer a place for muddy shoes, bikes and storage.

Upstairs, minor adjustments – including a small rear extension, and a levelling of the floors – introduce an additional bedroom and rationalise some of the quirks of the existing layout.

Massing has been rationalised to limit cold-bridging and introduce additional insulation to the external walls and roof. Higher-performance windows, improved glazing, canopies and overhanging roof construction help mitigate solar gain internally.