With an undersized old toilet and an inadequate wash-handbasin, which in excess occupied badly needed space, and no place to integrate a new lavatory into the existing joinery, a sanitary addition proved to be the logical solution. The minimized programme provided for a lavatory bowl, an Asian water closet, which may also be used as a sink, and a wash basin gutter. The box-like annex consists of a concrete base slab, which is closed in by concrete walls on two-and-a-half sides, a system of binders and joists, and ventilated facade- and roof panels made of Stearling-Board cork slabs.