The site for this project is in a leafy suburb set on Lansdown Hill within a Conservation Area forming part of the World Heritage City of Bath. The existing house is one half of a typical pair of semi-detached houses built in the 1960's in the City using reconstructed Bath stone blocks. The house is set on a sloping site and already had a rather plain two-storey extension providing a double garage at lower ground floor level with a sitting room above. This has now been replaced with a new three-storey extension. The new extension provides: a new kitchen, wc, utility and breakfast room at lower ground floor accessing onto the rear garden; a new entrance hall and sitting room at ground floor level and at first floor a new master bedroom with en-suite bathroom and dressing room. The design approach was to leave the existing semi-detached house unaltered externally with the new extension linked to it by a light glass structure containing the entrance hall and new staircase. The new extension is built of natural Bath stone ashlar and cedar cladding with powder-coated aluminium windows all under a low pyramid-shaped zinc covered roof. To the rear both the sitting room and master bedroom have glass fronted balconies affording extensive southerly views to the City of Bath below. The new staircase is constructed within the glass link and is made of white powder-coated steel with natural oak treads and a balustrade of stainless steel and toughened glass. The glazed link has natural ventilation provided by electrically operated high-level opening windows controlled by an internal temperature sensor.