The entire building and terrace are covered by a large roof. The café space inside the building and the luxuriously spacious terrace are connected to form a large working space. The 12 m high roof ridge is made of five larch trees joined together without bolts or metal fittings using a traditional method known as Kanawa-jointing. Large single glazed doors allow an unobstructed view of the outside from inside.
The building is characterised by the shi-jo construction, in which pillars are placed on natural stone, and the kake-zukuri and nuki structures on top of the pillars. Kake-zukuri is an architectural style in which a building is built on land with a large difference in height, such as a cliff, with long pillars and stiles fixed under the floor. The famed Kiyomizu-dera temple in Kyoto is a well-known example of this architectural style. Nuki structures are horizontal timbers that are passed between vertical timbers such as pillars in wooden construction. The number of 88 sokuseki and 108 kinrin-tsutsugi (joints) is a series of auspicious numbers associated with the name of the house.
The larch used for the pillars of the main roof and the red pine timber used for the curved beams were cut and milled in this forest. One of the highlights of the building is the rustic-style double-beam construction method, in which the climbing beams and columns are sandwiched between two bent beams and fixed with large bolts. The terrace is nearly 4 m above ground level, offering a spacious treehouse, bird's eye view experience.
The triangular trusses, consisting of beams, columns and climbing beams, are built like those of the Tomioka Silk Mill in Gunma Prefecture. The rustic shop's processing plant is built with a similar structure and is used for large buildings that require fewer pillars and larger openings. The long, narrow 4 m horizontal slit windows are also flooded with sunlight and natural scenery.
The Mizuya building, from which the name of the building derives, originally means a cupboard, a water closet in a tearoom, a shrine or temple sanctuary or a washroom. The building is also equipped with toilets and shower rooms, which are essential for a stay-and-work workplace. The spacious loft is also open. The washbasin and shelves also utilise solid materials.
The counter and kitchen are set up to make you feel at home indoors. The mortar walls have an austere finish. There is also a good number of bookshelves and overhead storage.