At 300 millimetres in section, Valhalla – a new elevation for a house in Highgate – is the thinnest project we’ve ever done. The house, designed by John Winter, is one of a triptych of modernist homes on a steep hill through the cemetery. We chose a vertical grid of charred larch fins to cover the tired façade, contrasting with the living trees opposite and reflecting our clients’ interest in the macabre. Reading as a solid on the up- or downhill approach, the gaps between the fins open on passing to reveal the ghost of the original house behind.