In an era of tight budgets and sophiticated digital tools, architects take modular construction beyond the single-family house.
After they are in place, Star's clustered modules will receive stucco facades, applied by Westport, whose workers will also install the building's open-air, steel-framed corridors. In addition to providing the main circulation infrastructure for the building's residents, the walkways serve as the distribution channels for utility lines that will connect above each dwelling unit's entrance to the factory-installed electricity, gas, and water services in individual apartments.
Forest City Ratner plans to build the modules for the B2 tower in Brooklyn, not far from the Atlantic Yards site, in a factory it is setting up with XSite Modular, a modular-building consulting firm. Because the larger apartments will be made of multiple modules, fabricators will need to assemble 930 in all. Although very few are exactly the same, there will be about 24 “families” of similarly configured modules, says Jonathan Mallie, a SHoP principal.
Each module in the B2 tower will have a tubular steel chassis that will be fabricated outside the city and delivered to the Brooklyn factory assembled. The chassis, which are 15 feet wide, 10 feet tall, and up to 45 feet long, are made up of Vierendeel trusses, which are distinguished by fixed joints and the absence of diagonal members. The configuration facilitates placement of openings between the modules, explains David Farnsworth, a principal at Arup, the B2 modular project's structural and mechanical engineer. However, diagonals will be added in some locations where they won't obstruct the connections between rooms.
Carpenters, plumbers, and electricians will perform almost all the fit-out work of the B2 chassis in the factory, building a floor and ceiling assembly for each module and adding partitions, finishes, and subassemblies, including bathrooms, cabinets, and m/e/p services. Only one hallway in each apartment will be left incomplete, to allow contractors to make riser connections between units in the field without disrupting already in-place finishes. The building's metal-and-glass cladding will also be installed at the factory. Each module's section of exterior skin will mate to the one next to it with self-sealing joints, much like those typically used on unitized facade systems.
Before starting fabrication of all 102 dwelling units for the Star Apartments (top), Guerdon Modular Buildings assembled several prototypes (middle) in its Boise, Idaho, plant. The wall assemblies of the mostly wood-framed units include a composite of steel and gypsum board for resisting shear.
Images courtesy Michael Maltzan Architecture