A new roof extension on a Georgian townhouse created an opportunity to build a two-bedroom maisonette with rooflights to all the rooms. The party walls were raised, and new steel cross beams installed at high level. A steel frame was then attached to these beams to support the two floors of the maisonette below. This structural method placed no additional weight on the internal structure of the original building. With the advantage of a steel frame, the mansard roof at the front of the new extension could be set back behind the parapet, leaving space for a full-width rooflight for the master bedroom below. A glass floor to the balcony at the back provides the full-width rooflight for the second bedroom. A double-height volume leads up to the living room and kitchen on the upper floor. This space is arranged as a form of pavilion, surrounded by frameless glass rooflights. A cantilevered sofa, which floats above the floor, is suspended over the entrance hall below. Sliding glass doors to the balcony can be stacked to one side out of sight. A sliding window, aligned with the stainless steel table, can be fully opened connecting dining to the sounds of the city. In mild weather, with all the glass slid out of sight, the living space pretends to be outside.