Despite the low floor area ratio allowance, the maximum building height at this site is indeed allowed to be 20m only if the volume is adapted to the complicated shadow calculation, although most of the buildings nearby are kept lower than 10m to avoid extra code compliance processes. While this 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 massing taller on the northern side is a result of our thorough volume studies with shadow parameters to elevate the duplex residence higher than neighbouring roofs while maximizing the building volume, which provides open views all around the residence with multiple levels of abundant roof terraces.
Located in a mixed area with commercial and residential uses in Sendagaya near the National Stadium in Tokyo, this project is composed of two stories of tenant spaces and the client’s residence above them. With only 160% of the maximum floor area ratio due to the narrow front street, the main challenge of the project is how to accommodate both comfortable residential environments and sufficiently profitable tenant spaces together, while maximizing spatial volume within the site constraints. 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 area in the denser neighbourhood. Thus, we tried to make it as open and generous as possible by actively incorporating outdoor spaces, despite the difficult site constraints.
The floorplate shapes are uniquely skewed at each level according to the shadow regulation, usages, spatial sequences, and vertical relationships. This stack of different floorplates generates shading overhangs and various outdoor spaces such as external hallways and 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 facades around the slab volumes are wrapped by the metal bands with repetitive vertical slats like louvers, which are designed from the positive interpretation of the code requirements forcing vertical slats design to rooftop balustrade to conform to 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 are enabled to extend towards the generous planted terraces to become a part of 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, another roof terrace spirals up to the wide slope covered by the artificial turf, an exclusive playground almost floating over the sky. As a result, a spatial continuum of inside and outside runs 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 the elaborate analysis and studies of the conditions and the limitations, we believe that the discovered potential of the site was well integrated into the distinctive architectural presence specific to this project. Its appearance looks like a fortress standing up in the urban fabric and hilly oasis with lush nature hidden behind. 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.