Extensions at Hessel Road

Works comprised:- internal reconfigurations to provide a new efficient layout that made the most out of the original house’s modest size; a single storey ground floor rear extension with an interlocking diagrid roof in structurally laminated beech; and a dormer roof extension finished in a rainscreen made from fibre-reinforced reconstituted slate panels with concealed fixings and rainwater goods.

The extensions are the result of the need to build quickly and economically and act as a test bed to advance technologies with bigger buildings in mind, in the tradition of Architects being their own guinea pigs – they act as prototypes for digital techniques of pre-fabrication and lightweight sustainable dry-fit construction systems for application in future larger projects. The owners themselves acted as the Main Contractor and installed all dry-fit construction, including bespoke cladding, second fix joinery and panelling. The ground floor extension’s asymmetric gable-ended form consolidates the bulk away from a particularly sensitive neighbour’s existing window near to the boundary in a way that is sympathetic to the existing windows above and relates directly to the organisation of the plan at ground floor level. To minimise time on site, complex roof joints were devised and machined offsite on a 6-axis cnc mill so that individual continuous members interlock to a single millimetre of construction tolerance and join without the need for any mechanical fixings, akin to how a piece of furniture might be traditionally made. The structural frame was erected on site in a single week by two labourers. The triangular geometry of the new extension’s beech diagrid roof visually widens what was originally a cramped and narrow interior to appear to inflate the house’s sense of space.