Sayama Forest Chapel. Sayama, Japan
Sayama Lakeside Cemetery Park is situated in the verdant surroundings in the Sayama hills.
In marking its 40th anniversary, the Cemetery Park decided to rebuild its chapel and community hall. We were chosen from among several firms in a design competition.
Sayama Lakeside Cemetery Park Chapel stands by the cemetery’s boundary adjacent to a deep forest. In believing that all visitors would hold similar feelings toward the forest where the deceased sleep regardless of their religious beliefs, we sought to produce a space for offering prayers toward the forest, nestled among the trees. To give the chapel intimacy with the forest, we planted trees on the cemetery side, and designed a building that merges with its encompassing trees.
So as to avoid the trees and their branches, we tilted the outer walls inward. This resulted in a gassho (“hands in prayer”) style building, formed of pairs of sasu (sloping rafters joined together at the top). The traditional gassho structure also requires seismic walls in addition to the paired rafters, but by further developing this style in an omnidirectional sasu structure, fitted into spaces among the trees, we enabled the roof structure to self-support horizontal as well as vertical loads. As a result, the seismic wall which was thought to be a necessity for a truss-system roof could be eliminated, and we obtained a gassho style building of a simpler and more contemporary form.
To prevent buckling, the rafters were made rigid using structural plywood. By choosing a slender 60mm width for the rafters and beveling their corners to radius 9R curvature, we imparted the fineness of a finish material to the structure’s interior appearance. The ridge beam and all metal connections are hidden to produce an impression simply of rafters rising from the floor. The result, a simpler, more contemporary gassho structure formed only of continuous sequence of rafters. Soft tree-filtered sunlight penetrates through the 251 rafters of the roof to animate its interior space.
To ensure long durability and permanence of the chapel, we applied random-cut aluminum tiles, sand-cast at a foundry. The tiles are 4mm thick, the minimum thickness for durability and maximum thickness for bending them by hand according to the curvature of the roof. The floor is finished with a natural stone (Inai-ishi slate) which has a rough texture from the wedge marks by stone-splitting. Like the flow marks visible on the aluminum roof tiles, the floor stones suggest (in appearance) the power of nature beyond human control. Just as we actively sought to draw sunlight and other natural phenomena into the interior space, we also endeavored to express natural phenomena through texture on a material level. I felt that establishing such dialogue with the vast mystery beyond human affairs was suitable for a chapel.
The floor inclines slightly toward the forest on the altar side. The joints of the floor stones also run radially in lines toward a vanishing point deep in the forest. Upon entering the building, visitors move unconsciously toward the forest. When a person clasps hands to pray with fingers locked, a small, warm space forms between their palms. We took this small prayerful space and embodied it in a building. It is a chapel, thus, that prays together with the visitors.
Because each of the 251 Japanese larch rafters differs in length and orientation, we cut them on a numerically-controlled lathe based on the precise 3-D modeling data, and produced them within a 3mm error range even with their maximum 9m length. Since the paired rafters are freestanding with one supporting the other, we inserted a connecting plate into their upper end and secured the plate with drift pins. The paired rafters, thus pre-connected and forming an upside-down V were hoisted and dropped into position. To join the rafters to the base plate, round holes were cut in the foot of each rafter for mounting them on round bars protruding from the base plate. A drift pin was then knocked into the mounted rafter through a hole in the round bar. There was a concern that it might be difficult to connect both feet of the paired rafters to the base plate with any slight discrepancy. However, by developing a special jig, we could limit the variance between the rafter and the round bar of the base plate to 1mm. As a result, despite a succession of difficulties hindering the construction process, we achieved a gassho structure of pure form.
