This house is the first digital fabricated architecture in Japan as a permanent building. Through the project, we've tried to combine the Japanese traditional technique of wooden structural joints and digital technology with using machines.
The shape of this architecture is referred from a roof truss of "Gassho-Zukuri '' which is the traditional housing type in this area.
And all the timber material which we used was cut from the forest around the area, and they were processed to the structural elements in the small local timber manufacture factory. The factory used the shop-bot which was provided by VUILD. Along the latitudinal direction, the truss, which is composed of the "Gassho-Ita"(30×430mm) tilted at 70 degrees and arrayed on every 1m resists horizontal force.
Due to the limitation of the material length, ''Tie-beam'' also works as the connection piece for joints of gasshou-boards. Along the longitudinal direction, the structure is planned by the stiffness of "Nuki-Ita" (flat use) and '' Waku-Ita'' (vertical use) . The '' Nuki- Ita'' (flat use) is effective against the out-of-plane wind pressure, and at the same time, it has the function as a buckling stop of the thin gassho-board (30mm).
The joint of the '' Gassho-Ita '' is stopped to rotate using four drift pins, and the end of the processed tie-beam is inserted from the side.
A drift pin that has a lot higher shear strength than a timber dowel is used, it works for minimizing the lack of cross-section of the gassho-board and secures as much effective range of the inside space as possible by making the height of the beam small. On the top of the gassho-board, a board is added simply and tied with drift pins.
The '' Nuki-Ita'' connected from right to left of the gassho-boards is used as a finger joint via '' Gassho Ita'' and tightened with some timber dowels such as Japanese traditional joint system.
The mortise processed frame plate is inserted to each gassho-boards and construction lumber from its side, resisting the axial rotational rigidity against the Longitudinal horizontal force.
Normally the out-of-plane direction of the frame plate tends to expose to negative wind pressure, however, the area (width 2000× length 1000mm) and also the pulling force are not that large, therefore we used not screws but seven N90 nails every span to resist the pulling force and anti-slip.
The structure of the architecture consists of hybrid material such as timber, steel and concrete. We've carefully chosen the material of structure and where to use them, based on structural reasonability. The back side of the basement was needed to resist soil pressure and to have a water-proof spec, therefore, it was chosen concrete.
In order to resist the seismic load, we needed walls or steel braces on the transparent facade side, since we don't prefer the visible bracing system, we chose two walls but they should have been preferred as thin as possible. We set in front of the facade minimum length and minimum thickness which was required in the building standard symmetrically.
Eventually, they became a great eye-stop between the interior space and the green in the garden which is designed by the gardener client.
In order to avoid putting columns on the upper floors, we used steel I - beams efficiently for primary beams to minimize the thickness of the floor. A rest of beams consit by construction pine-lumber.
In this project, we planned the structure to use a total floor area of 87.23 ㎡ effectively, including the required functions; a gallery, and a multi-generational house.
Firstly, the roof, the floor, and the walls are made using 105mm pine wood. On the vertical side, we adopted a 12mm structural plywood as double side panels adhered to the column and beam using glue to solve the weakness problem of the high floor and the wide span.
The "Roof wall" which receives a load from out-of-plane direction under long-term loading has one 125 ×125mm steel beam on the direction perpendicular to the ”Diagonal wall”, and its stiffness is evaluated as a wide flange column in case of the Typhoon. By doing this, the thickness of most of the walls is planned 129mm that is the same as the beam’s including structural plywood, therefore, the space in this structure was uniform in case of thickness. The ”Diagonal wall” dividing the house into north and south plan which has the role of an exhibition wall of the gallery can satisfy the requirements of longitudinal wall quantity after the resolution of a vector and structurally has high stiffness in terms of the calculation of the fourth division method. In this project, we could propose a new possibility, to secure the big volume inside consisting of thin roofs and floors as the walls, rather than not getting caught up with the idea that floors and roofs are normally thicker than walls.
The first project was completed in Hong Kong in 2015.
A pavilion consists of some large swings with different directions.
The first image which the architect LAAB shared with me was the roof was supported by many very slender columns. It was very beautiful. However, since the vibration comes from movements of swinging differently when there are many people used, we needed to have a solution to resist the force.
And, instead of making those columns thick, we suggested a totally different structural system called the '' SWING STRUCTURE''.
The structure basically consists of leaning columns to resist the horizontal forces caused by the people's swinging movements.
It looks like leaning diagonally and doing ''swing dance'' from the 1930s.
In this project, it was first planned from a small 1.82m grid plan, and we thought it is important to include the structural elements as thin as possible from below for two reasons.
Firstly, we thought that high ceilings such as 3.3m, which are beyond normal height and cover the wide area of this house, can be a big characteristic in Japanese modern houses.
Additionally, the thickness of the columns was planned to be less than 105mm to express "the unmeasurable condition from the experience" as the purpose of this design plan, rather than using a thicker column than 105mm square.
Secondly, the aim was to achieve building an abstract, elegant, and balanced volume, which still has columns arranged finely, by planning the cross section of columns and beams using the same thickness, and a 90mm square column, which can be used as a minimum dimension of widely available lumbers.
In the earthquake resistance plan, only the outer walls are treated as the structural wall, and the inner walls can be treated as a weak structure, therefore people can impressively recognize the inside of the house as one volume. The floor and roof located on the outer side are effective against the wind pressure measures, also they are the rational plan to integrate the elements of the design and the structure.
The grid roof exaggeratedly exposed to the outside is continued inside as the same system. inside, the slimmer steel columns are used than outside, giving people the experience of the different sequence.
However, in fact, this grid roof and steel columns don't continue to the hidden wall and roof on the west side, but it consists of just a combination of wood columns and beams which array reasonably and orderly.
In this project, we adopted "The fictionality" which is required on the things between experience and support in the architectural design.
Normally, the structure is not exposed to outside all the time; therefore, I expect it also has another possibility that completes a story that a designer wants to express.
The acorn-shaped hut is a camping unit. All the material was processed by a CNC machine, so called digital fabrication.
The structure simply consists of a back plate and two rib-plates, they are all made of 24mm structural plywood which is the standard spec in the market in Japan. The Japanese clog-shaped unit. They are stacked in 5 layers, fastenned the upper and lower rib plates with two bolts.
As a result, they are able to be evaluated as continuous columns and are a structural system that resists bending moment caused by the long term load and also the horizontal forces such as Typhoon and Earthquake. The back plate acts as a buckling prevention in the thickness direction of the thin rib plate ( meant columns), at the same time, and a role of increasing the horizontal rigidity in the surface. Since the project meant to make an alternative idea of a tent, we've aimed for a structure which can be created in a simple and primitive language while being aware of temporariness and simple details to achieve to assemble easily.
The architecture has a very simple and unique program as seats for the cat café.
The whole structure is suspended by the roof, composed with Hinoki timber and steel standard profiles which include a square shape and a flat plate. The structure has been very carefully designed and optimized those structural elements by depending on what kind of forces to support/ resist.
The pavilion was a temporary playground located in Yuen long, Hong Kong. The requirement of the structure was as simple/ slender as possible. The structure consists of 50mm diameter steel columns and 50 x 20mm rectangular section ring- shaped beams.
The columns and the ring-shaped beams are connected by bolts, this atypical framed system achieved to resist horizontal forces such as Typhoon.
The base of the columns selected an improved sleeve joint to make the assemble and disassemble easier.
The house is located on Easter Island, 3500 km away from the mainland Chile. The island is most famous for its nearly 1,000 extant monumental statues, called moai.
The difficulty and unique point of the project was limitation of the materials which we could choose for the structure. Due to the location being isolated, the construction materials we could use were limited than general projects.
We simplified the structural elements as much as possible.
The roof consists simply of a CLT panel 70mm which is in circulation for the general house constructions in this island, the shape looks triangular just like a standing book open. We also use the CLT panel 120mm for the timber bearing walls. And the rest of the structure was used for construction lumber such as the double ridge poles, tie-beams and columns.
In addition, we use the soils from the ground which is beautiful red to mix the concrete for the bearing walls.
The 6m long columns located in the entrance hall are required to resist wind pressure out-of-plane direction. We expressed the visualization of the force of resistance that the outer wall receives, by planning the columns a bit thicker than the minimum required cross-section and setting it outer of the finished wall.
We put many thin walls as a "non-structural wall" which supports no horizontal force such as an earthquake.
It is composed of base materials of 30mm thickness columns that are extremely thinner than general use 100 mm for ''non structural wall'' and are used as the minimum dimension to stand on itself. It expresses its fragility as a characteristic of a non-structural wall.
By expressing the contrast between the above‐mentioned forceful columns and fragile walls strongly, we establish connections between the structural elements in one space and achieve a relative structural design.
Through the project, we tried to express the force which a structure receives as the design, by generating the contrast of the relative composition of ''mezzo piano'' and ''mezzo forte''.
This is one of the important themes for our structure design.
The wall panel consists of 50 x 3 aluminum squares columns, and 2 mm structural aluminum plate is welded, and then covered with a 2mm finishing aluminum plate which is bent into a U-shape. The panel size is 450mm width and 3m heights. They were brought to the site as a panel which was pre-assemble in the factory to reduce the construction time on site.
In addition, the roof louvers consist of aluminum flat plates were welded to both ends and unitized to 1 m width at the factory. This panelizing and unitizing achieved a size and weight that can be carried by a craftsman alone, it was possible to complete the construction in a single day with only a stepladder without scaffolding. Aluminum panels required ''alumite treatment'' to prevent rust, but the general method eliminates the nice reflection which a pure aluminum plate has, therefore, we solved the remaining reflection by shortening the treatment time and reducing the penetration thickness.