Crowded and budget-constrained, the East Hampton, N.Y., Springs Union Free School District found a way to accommodate its growing school population, and implement technological and compliance upgrades while controlling costs — all with minimal campus disruption. Designed around a new school building system developed by Oldcastle Precast Modular Group (OPMG), an 8,820-sq.-ft. addition to East Hampton's Springs Union Free School provided four general classrooms, a science laboratory, and multipurpose space in addition to retrofits to the existing facility.

According to School Board President Tom Lawrence, the $2.2 million project required only five months from production start date to occupancy, and was completed with considerable savings in both time and expense. Additionally, using the OPMG component system allowed the school district to circumvent the problem of a shortage of construction workers in the area, which likely would have delayed completion and added costs to the project. While alternative construction methods were considered initially, Lawrence reports, the final decision was made to use Oldcastle's precast components when the board learned this system would double the insulation R values and offer an attractive finished appearance to blend with the school's brick exterior.

The 75-ft. 8-in ∞ 126-ft. structure comprising the addition was constructed with 41 precast building modules. The design employed 26 four-sided, 8- ∞ 32-ft., ring-style, structural modules (NT32s) and two fully outfitted, ceramic-tiled bathroom modules, all bearing integrated insulated, brick veneer exterior walls and factory-painted interior walls. When erected on either side of the corridor area, the NT32 modules along with 13 precast wall panels, folding partition walls and EPDM roof, made up the four, 785-sq.-ft. classrooms, one science lab, one art room and corridor that attached to the existing facility.

The system components were produced in precision forms with 5,000 psi concrete mixes in either 8-, 10-, or 12-ft.-wide sections and 32-ft. spans with provisions for windows and doors. The components have a 1½-in. roof slab supported by 15-in.-deep precast beams, 2 ft. 10 in. on center, similar to a double-tee cross section without prestressing strand. The insulated sandwich walls were configured with a 6-in. structural wall, either 2- or 3-in. polystyrene insulation board, and a 4-in. exterior face that accepts a variety of finishes, including paint, form liner finishes or cast-in-place brick facing. The waffle-pattern bottom of the 8-in.-thick floor slabs, typically extending to intermediate, cast-in-place grade beams, served to reduce concrete consumption and minimize weight. As designed, the building components incorporated plumbing runs, communications cable and electrical conduit, electrical devices, door and window openings, a wide selection of chalk boards, trophy cases and other optional school fixtures.

The prefinished, structural modules were manufactured in 28 days using three forms in a five-day process. For the exterior wythe form — the first to be prepared — integral brick veneer facing was placed in addition to steel reinforcement and subcasting void assemblies for doors and windows. After pouring the mixes, insulation was positioned, while the concrete was consolidated and cured overnight.

On the second day, the exterior wythe section and steel reinforcement, various embedded items, conduit and additional subcasting voids were installed onto the second form, creating a three-sided component. In addition, a third form was prepared for casting the floor slab. Again, concrete was placed, consolidated and cured.

Components were removed from the forms on the third day and attached to produce a four-sided building module. Finishing to achieve uniform surfaces completed the casting process. Finally, interior vertical surfaces were painted; and, where applicable, ceramic tile and electrical fixtures and devices as well as plumbing fixtures were installed.

On the fifth day, the components were inspected and placed in the yard or shipped directly to the school site for erection. Weighing just over 20 tons, the 32- ∞ 8-ft. building modules were set side by side off the trailers using 175- and 165-ton hydraulic cranes. Over the course of five days, the building enclosure was completed as wall panels were attached and finish work was accomplished. In addition, retrofit work upgraded the circa 1950 portion of the school with replacement windows, reconfigured music suite, business office and special education areas and brought the bathrooms into compliance with current standards.

OPMG representatives note that using the NT32 school modules — designed, engineered, produced off-site and erected by a single source — reduced the project's overall cost by 12 percent and the construction schedule by an estimated five months. The modular building system, they emphasize, provided a durable, low-maintenance, thoroughly insulated and structurally integrated facility while decreasing labor costs, on-site construction, erection and finish work by more than half with minimal interruption to school routine.