Portsmouth

Porter Robson was appointed to deliver the conversion and extension of an existing office building in Portsmouth, to create three new residential apartments through the careful reuse of the existing structure and the transformation of its roof space.
The project makes extensive use of the existing building, reorganising its accommodation for residential use rather than pursuing wholesale redevelopment. The ground and first floors are converted to form new apartments, while the roof is substantially reworked to create additional living space within a new upper level.
The resulting mix comprises a one-bedroom apartment and two two-bedroom homes, allowing the existing building to be intensified while remaining appropriate to its established urban setting. The layouts incorporate open-plan kitchen and living spaces, private bedrooms and bathrooms, together with shared circulation, cycle storage and refuse provision.
A key part of the architectural strategy is the treatment of the roof. The former roof space is reshaped through new pitched forms, dormers, rooflights and carefully controlled flat-roofed areas, allowing the upper apartment to gain useful floor area and natural light without simply adding a conventional full storey. The altered roofscape gives the building a stronger domestic character while helping the additional accommodation sit comfortably within the surrounding street.
Externally, the proposals retain the proportions and rhythm of the existing elevations while refreshing the building through a restrained palette of render, dark-framed windows and tiled roofing. New dormers and roof openings are integrated into the roof form rather than treated as isolated additions, giving the enlarged building a more coherent residential identity.
The refurbishment also provides the opportunity to improve the performance of the existing fabric. The technical design considers upgrades to insulation, airtightness, existing masonry cavities, window performance and thermal bridging, ensuring that the conversion improves comfort and energy efficiency alongside the spatial transformation.
Portsmouth Apartments demonstrates how an existing commercial building can be adapted, intensified and given a new residential life, combining retained fabric with targeted architectural intervention to create three contemporary homes within an established Portsmouth streetscape.