Situated on the outskirts of Guildford, Surrey, with a direct view of the North Downs on the horizon, CASA BASSA is a small house built on the footprint of a previously nondescript garage. The design aims to redefine a typology by combining multiple dwelling types, creating a hybrid house that can adapt to various uses and layouts. Upon completing the refurbishment of their contemporary villa, which included grounds designed by garden designer Adolfo Harrison, the clients approached FPA for a creative solution to expand their space. They sought to accommodate friends more comfortably, allowing them to fully enjoy the house and gardens together. The initial investigation considered redesigning redundant rooms and converting attic spaces, but it was soon clear that a standalone building would offer a more memorable experience. As the design evolved, the new structure was envisioned as a versatile space, providing an escape for the teenage daughters, an occasional office, a gym, and guest accommodations. Loosely inspired by concepts derived from artificial intelligence—the owners’ field of expertise—the design draws from AI algorithms, translating code into binary patterns of 0s and 1s. This concept is reflected in the architectural language, where a vertical binary rhythm influences the selection of technical solutions, materials, and finishes. Elements such as timber goalpost frames, zinc cladding, charred timber, battens, and porcelain tiles are meticulously arranged in binary patterns of seam and field, solid and void, gap and slat, ridge and valley. The result is a dynamic and structured interplay of textures, celebrating the intersection of technology and craftsmanship. The entrance is subtly marked by a sculptural set of steep steps, which navigate the garden’s level changes. The doors and openings are cleverly disguised within the timber cladding. The steps, wall, and floor, creating a small open-air antechamber, are clad in green patterned tiles that establish a distinct connection to the landscape, setting the space apart from the building. The plinth of the original garage has been preserved, with its layout unchanged to reuse the existing footings. A mansard-style roof, higher than the original, has been added over the plinth to create an open space accessed via a double-height area. The dynamic roof shape responds to the site’s topography, resulting in elevations that vary significantly on each of the four sides. While the exterior of Casa Bassa is dark and monolithic, the interior presents a stark contrast—bright, monochrome, and flooded with natural light. The loft-like open space engages with the outdoors and the hills beyond through expansive picture windows, creating a seamless connection between interior and landscape. There is a deliberate sense of surprise for visitors, who enter through a hidden, small door and traverse a dynamic, funnel-like stairwell before emerging into the expansive interior—a progression of emotions from enclosure to openness. The use of simple, standalone volumes for the kitchen and storage (which also doubles as a bedhead) is cleverly located on the upper level, helping to break down the open space and effectively zone the area. The extensive use of timber and timber-based materials, the reuse of significant portions of the existing structure, including original steel girders, and the incorporation of sustainable materials paired with high-level insulation have all contributed to creating a building that prioritizes sustainability. It boasts a low carbon footprint, high embodied carbon efficiency, and a substantial percentage of recyclable components.