Excerpt: IBIS Sendagaya is an architectural project designed by KOMPAS in Japan. This project is intended to suggest one way of the approach towards mixed-use development and living spaces in the urban context. They tried to make it as open and generous as possible by actively incorporating outdoor spaces, despite the difficult site constraints.
[Text as submitted by architect] Located in a mixed use area in Sendagaya, near the National Stadium in Tokyo, the project is composed of two floors of tenant spaces and the client’s two-story residence above them. The main challenge of the project is how to accommodate comfortable residential environments and sufficiently profitable tenant spaces within the site constrains, which allowed only 160% of the maximum floor area ratio due to the narrow front street.
The client, a family of five who used to live in an ample detached house with a garden, had concerns about the spatial quality of their new house with less available floor area in a denser neighbourhood. Thus, we tried to make it as open and generous as possible by actively incorporating outdoor spaces, despite the difficult site constraints.
Despite the low floor area ratio allowance, the maximum building height of the site Is defined at 20m If the volume is adapted to the complicated shadow calculation. However, most of the building nearby are kept lower than 10m to avoid extra code compliance processes. While the neighbourhood is relatively dense on the street level for residential use, we found potential open voids to create comfortable environments above the surrounding low buildings. Therefore, the building volume was developed to be taller on the northern side, elevating the duplex residence higher than neighbouring roofs while maximizing the building volume and capturing open views over the surroundings.
Each level’s floor plate is uniquely skewed according to the shadow regulation, usages, spatial sequences, and vertical relationships. This stacking generates shading overhangs and various outdoor spaces such as external hallways and green terraces without interrupting GFA limitations. Besides the closed building facade along the site boundary accommodating main loadbearing walls, the articulated deep concrete beams allow the façade structure along the terraces to be open and transparent encouraging inside and outside to merge. Large timber window walls recently certificated for fire resistance deliver open and bright interior spaces, unlike typical fireproof buildings required in most of the dense urban areas including this site. The void space around the building with distributed lush vegetations at each terrace forms a cascade of sequential vertical gardens like a canyon stretching from the bottom courtyard towards the sky.
The resulting structural depth about half a storey deep functions as servant layers between each floor, providing infrastructural supports to the floor below and above such as mechanical space, attic storage, loft, underfloor storage, planting pit, etc., which allows the main spaces to be more open and flexible. The linear façades around the building’s slab volumes are wrapped by metal bands with repetitive vertical slats like louvers. Their design comes from the positive interpretation of the code requirements forcing a vertical slats design on the rooftop balustrade to conform the shadow regulation. The continuous vertical louvers allow for interplay between openness to the perpendicular views and privacy from the diagonal views besides enhancement of horizontality of the floor layers.
The top floor of the building, the entrance level of the duplex residence accommodates the tall and generous single room with clerestory windows for the living room and kitchen. On the floor below, the triangular hall surrounded by the bookshelves anchor four bedrooms and bathrooms. Through the fully openable sliding windows at each floor, both the living room and the hall can extend towards the planted terraces and become a part of the living spaces. While the generous stairway with the study corner connects the living room and the hall openly to create a continuous spatial strip, two terraces are also connected through the outdoor stairway surrounded by abundant vegetation. Beyond the clerestory window of the living room, a roof terrace spirals up to the wide slope covered by the artificial turf, resembling an exclusive playground almost floating over the sky. Openly connected generous spaces create a spatial continuum of inside and outside throughout the duplex and three levels of the terraces, which forms a sort of a ‘three-dimensional loop’ of the living spaces. Various casework and vegetation are distributed along the periphery of this living space loop, creating different characters of the places. Besides joyful kids running around, light, air, view, and all the flow of life and nature circulate seamlessly throughout inside and outside.
Through an elaborate analysis and studies of the site’s conditions and the limitations to make use of Its full potential, a distinctive building resembling a fortress stands out from the urban fabric thanks to Its irregular terraces and lush vegetation. This project is Intended to suggest one way of the approach towards mixed-use development and living spaces In the urban context. At the same time we purely pursued the sort of abundant and enjoyable living spaces where we would almost feel envy the kids growing up there. We hope for the client to enjoy their new life surrounded by the Tokyo skyline.