Prefabrication experiments - 113 - Structures - 4 - Volumetric or box type construction

Also described as volumetric construction, a box structure is basically a rectangular prism component for building. Volumes/modules are either self-supporting or designed to sit in or to be supported by a separate collective infrastructure. The rectangular prisms are usually defined according to standard regulated shipping dimensions and can be completed to varying levels in a factory. The combination of manufactured boxes informs building erection with a potential «toy building block» variability.

The particular advantage of volumetric systems is that much of the construction process takes place within a quality-controlled environment. The factory setting is accommodating and a streamlined organization of procurement, design and production is possible. Transportation costs and important investment in factory production comprise some of the drawbacks of off-site volumetric construction.

Boxes can be cast in concrete or assembled in wood or steel frames. Iconic 20th century box systems employed reinforced concrete or prestressed concrete. Concrete volumetric construction matured during Operation Breakthrough in the U.S. as the postwar building booms in industrialized nations underwrote the development of various concrete box systems designed and engineered according to their vertical and horizontal aggregation. The Habitat 67 prototype designed by Moshe Safdie in Montréal is one of the flagship examples of concrete box building. Reinforced concrete boxes were amassed in a dynamic form, which produced a canonical 20th century architectural marvel. The boxes were fabricated on site as an assembly line was established adjacent to the building site. Manufactured fibreglass kitchens and bathroom were fitted in the boxes.

Once assembled, volumetric construction is permanent, which renders future changes and adaptability difficult. This challenge has constantly argued for some type of hybrid system. For instance, the assembly of bearing service volumes over open frame structures would allow for some flexibility. Grouping has also been explored as a potential to achieve greater flexibility of volumetric building systems. The Shelley System patented in 1970 explored a checkerboard pattern of boxes in order to avoid double walls of adjacent boxes. Furthermore the pattern structured a series of voids accommodating adaptable spaces. The brick like pattern created a permeable structure. The staggered units were attached and post-tensioned by cables running through superimposed faces and ridges.

Shelley system patent drawing