A black box is an object whose inner structure is unknown. Of more interest is the functionality of the box. A single-family house was extended by a lateral, cubic extension on the ground floor. In contrast to the white painted existing building, the annexes were clad with black stained wood. The extensive glazing of the annex makes the black living box transparent, but the functionality of the newly created space remains invisible from the outside.

The ground floor of the existing building is about 90 centimetres above the outside area. The extension was built on a 45 cm high split level, which gives the new dining room a more generous room height and more privacy. At the same time, the split level allows ground level access to the terrace at the rear of the house. The flat roof surface of the cube also forms a terrace of almost 30 square metres on the first floor.