a house like a ship


located in the forest of karuizawa, a very popular destination with mountain resorts in japan, ‘long roof house‘ designed by yuji tanabe, mimics the form of a ship. a concrete cabin emerges from the ground, taking shape as a hull, an extended balcony acts as the deck of the ship, and a light wooden mass (partially steel) on top, as the pilothouse. this way the boundaries between the two volumes are clear, giving the impression that the above one is floating on the raised surface. 


the site slopes gently to the south with mountain asama in the background. this area had been damaged by pyroclastic flows due to the eruption of mt. asama about 900 years ago, and lava stones called ‘asama stones’ appear immediately after digging the site. therefore, the water drainage is good, and it is an area with relatively low humidity in karuizawa.yuji tanabe builds ship-like dwelling among woodland area in japanall images courtesy of yuji tanabe



approaching the ‘long roof house’


the architects (see more here) sought to create a path for the car, approaching the south side of the building, crossing between the trees, and parking under the eaves on the ground floor. the shed roof extends about 20m to make the most of the sunlight on the south side while avoiding the snow to drop on the parking lot. this proportion was decided from the plan of the part where the ceiling height is low and the shade regulation to the adjacent land. the outer corridor, which continues from the large deck-shaped balcony, goes around the building while shifting according to the slope of the roof above.

yuji tanabe builds ship-like dwelling among woodland area in japan
a swing with views opening to the forest



two different masses coexist harmoniously 


 the ground floor includes a semi-public space with the entrance hall, office, and the guest room, while, on the north side of the building, a stairwell leads inhabitants to the upper floor. the second level consists of the living place; kitchenette, dining table, bedroom, and bathtub. the openings are mainly placed on the long side (east) to let in plenty of natural light in the morning, capturing a sweeping view of the surrounding scenery.


as the dwelling is a mixed structure, it was important to maintain a balance between the concrete and wooden masses; the ceiling without pillars, RC (reinforced concrete) walls and beams on the first floor, are conscious of the large outdoor decks, pillars, and beams on the second.

long roof house 4
the flooring is clad with timber


the facilities are equipped with FF type(forced draught balanced flue) heating with kerosene in the main living room, heat storage type floor heating on the first floor, and wall heating on a part of the wall on the second floor. therefore, the plan is to make it available to owners who frequently travel to and from tokyo during the year. in the exterior plan, an outdoor space is formed with local asama stone on the east side while making use of existing trees. the continuity of the wooden approach on the first floor, the outer corridor on the second floor, and the eaves of the roof overlap in three layers. they cut out the scenery while spreading in the sky, and the diagonal lines can be felt from the interior as well. 




long roof house 5
a balcony spans on the ground floor’s roof



the outer corridor shifts according to the slope of the roof above
the outer corridor shifts according to the slope of the roof above
semi-public space
semi-public space
night view
night view

project info:


name: long roof house
designer: yuji tanabe

location: karuizawa, nagano, japan

structural engineer: low fat structure

landscape design: honda greem 

contractor: takehanagumi 

site area: 1084.30 sqm

built area: 116.12 sqm 

first-floor area: 104.57 sqm 

second-floor area: 89.14 sqm 

structure: reinforced concrete + wooden structure 

photography: yuji tanabe



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edited by: christina petridou | designboom