High Concrete Group LLC has introduced ThinCastTM, the thinnest precast concrete rainscreen panel available on the market. Designed for use in commercial, institutional, retail, and low- to high-rise construction, this innovation provides architects with the natural beauty and character of concrete in lightweight panels that accomplish their rainscreen design goals.
Location: Montclair, N.J.
Type of Precast: CarbonCast® Load Bearing Insulated Cladding
Size: 550,000 sq. ft. (264,000 sq. ft. architectural precast; 438,128 sq. ft. Hollowcore plank)
Innovations abound in all-precast college residence halls
Incoming students aren’t all that’s new at Montclair State University in Montclair, N.J. Many are living in residence halls that are part of the state’s first public-private partnership, in which a private developer built and now operates the project on public land. Further, construction was completed on a design-build basis, another first for public buildings in New Jersey.
The Heights, consisting of two separate residential complexes — Dinallo Heights and Machuga Heights — is the largest residential facility ever built in the state. With panoramic views of Manhattan to the east, the project is also the first application for CarbonCast Horizontal Insulated Cladding, a thermally efficient exterior fabricated by High Concrete Group LLC.
All the firsts owe to Montclair’s master plan, a campus redesign that physically reflects a shift toward a residential academic experience rather than serving primarily commuter students. The Heights houses 2,000 live-in students in eight wings that vary from six to eight stories in height, and that have footprints ranging from 7,500 to 9,500 square feet. The total building area is approximately 550,000 square feet, with a total budget of $211 million. The facility is registered for LEED Silver Certification.
If you’re wondering what Spanish Mission-style buildings are doing in New Jersey, it started in 1908 when the institution was founded as the New Jersey State Normal School. Built on an abandoned rock quarry, Montclair’s first buildings featured white stucco walls, low pitched tile roofs and southern atmosphere that characterized the architectural movement. After building in various other styles through the intervening years, Montclair is returning to its architectural roots.
The new structures, however, omit the stucco of the original. "We chose precast because we believed it would result in a better quality and more durable finish," says Steve Derochi, president of PS&S Architecture, PC, the design firm. "From a campus planning point of view, you can stack the precast system pretty high without a significant cost premium. Taller gives more density, which returns more bang for the land."
He notes that the system was chosen over cold-formed metal and EIFS, which had failed in previous structures due to wintertime application. "Precast eliminated fireproofing, which saved time and money," he continues. "No additional exterior finishes were required. In operations and maintenance, precast will afford the durability of masonry without the hassle of tuck-pointing, leaks, etc. And acoustically, the precast system’s mass will reduce sound-transmission between rooms and floors significantly."
The residence halls are enclosed with 11"-thick CarbonCast exterior walls that are load-bearing as well as thermally efficient. "Thermal mass is still a big deal in reducing operating costs," says Derochi. "The insulated panels also eliminated virtually any thermal bridges in the exterior wall system."
The composite panel construction consists of a three-inch face wythe of precast concrete, a three-inch thickness of rigid XPS insulating foam, and a five-inch concrete back wythe. The wythes are connected with C-GRID® carbon fiber shear trusses which have very low thermal conductivity properties. The wall assemblies deliver a uniform R value of 15. Large, solid panels at the ends provide shear support. Interior walls are steel trowel finished with paint in rooms and corridors, eliminating drywall. Painted plank eliminated the need for hung ceilings.
The southwestern-look façade has two precast concrete mixes, in buff and white colors. The elevations for the first two floors have a limestone image, while the upper five to eight stories are white concrete. Fabricated at High Concrete Group’s Denver, Pa., and Springboro, Ohio, facilities, the panels have bay window projections as well as bullnoses and numerous reveals. Using the master mold concept, High Concrete was able to gain forming and cost efficiencies, moving window block outs and creating left- and right-hand versions of panels in 26’- and 36’-length modules.
During the design-build process, the design team had determined that the mansard roof planned for the project was too expensive. PS&S and High Concrete worked closely to create an L-shaped eyebrow parapet alternative to the mansard roof. The 2-1/2’ to 3’ eyebrow projection saved approximately $1.5 million per building. Screens hide roof-mounted mechanical systems.
A track crane on each of the two building sites lifted the precast panels into place. To minimize downtime and erection duration, the buildings were constructed story by story, with each crane constructing two wings at the same time by alternating between them. "The structure was ready to accept rough-ins as soon as two floors were in place above, which expedited the other trades big time," says Derochi.
Key to the overall schedule was the weather resistance that the sandwich precast panels afforded. Unlike a batt insulation and drywall system, the panels did not have to be protected from the elements until the roof was installed. By using precast concrete the project avoided significant interior damage due to weather that can occur to other types of construction, particularly in the winter months, as well as additional field labor costs.
The metal-frame dining hall required open architecture from the inside to the outside that required unique framing developed at a low level under the exterior wall. The precast had to put in columns to carry the upper level exterior, remaining open to the exterior.
The developer, architect, construction manager, and precast fabricator worked together through the design-build process so that the module of the buildings to accommodate the industry standard 4’-wide hollowcore plank. Despite the large volume of hollowcore plank there was almost no cut down required.
Working the building size in early project development minimized changes to forming, unique sizes, and minimized narrow-width, non-uniform hollowcore that adds time and cost. This project was the first use of CarbonCast Horizontal Load-bearing Cladding, the first public-private partnership, and the first design-build contract for a state college facility. Derochi notes, "The project was designed and built in 20 months and constructed in 14 months, with the precast system being a major factor in accomplishing the aggressive schedule."
CarbonCast is a registered trademark of AltusGroup, Inc.
C-GRID is a registered trademark of Chomarat NA