When the clients bought a run-down two-storey house in a backyard in Paris it was initially uncertain whether a conversion or additional storeys would have any prospect of approval at all. But given the tight housing market in Paris they were willing to accept this risk. To create the space required by the four-person family the architect team proposed extending the building upwards by adding three floors. The house was tiny, with a footprint measuring just 4 × 6 m. The path from the first designs to the start of construction was a long and stony one, as to obtain the building permit both the authorities and the neighbours had be convinced by the proposed building that soars into the sky.