The original design idea of House 345 originates from the needs of its owners. Introversion and privacy were the two main components expressed by the owners. To achieve this goal as well as the creation of a space that will be used daily by a family, the design team decided to identify several imaginary zones, which will be implemented through physical and mental limits. The large wall of uncoated concrete at the facade of the building implements exactly this natural boundary that separates the interior of the house from the public space. It seals the privacy of the residence behind it, while the selective openings offer controlled entrances with different levels of security. The structure of a castle is restated here with a different vocabulary (with the same result). Bare planked concrete, as a simple, earthy material, with an internal structure similar to stone, functions ‘protectively’, while at the same time defining the boundary and the aesthetics of the house as a whole.