Being creative with tilt-up: as the tilt-up industry moves into the commercial office and retail market, the demand for creative, interesting structures increases

Concrete Construction, June, 2002 by Joe Nasvik

Tilt-up has long been regarded as one of the least expensive ways to construct buildings. At first, its primary market was warehouse construction--large, flat panels of concrete cast on the floor slab, lifted into position, and finished on the outside with a waterproofing application of paint or other material. Begun in the Midwest in 1910 with tilt tables to raise the panels, tilt-up construction has now spread throughout the United States. The real momentum for tilt-up construction, however, began in California in 1945 with the advent of the ready-mix truck and the mobile crane. According to Jim Baty, technical director for the Tilt-Up Concrete Association (TCA), Mt. Vernon, Iowa, "In 2001, the construction of tilt-up buildings topped 272 million square feet of wall surface. Of that total square footage, 15% to 20% was decorative wall construction."

The demand for decorative tilt-up is growing rapidly as the industry moves into other building markets--office, retail, public buildings, schools, and church construction. Painted, flat walls don't satisfy this market. Buildings must be eye-catching, and walls must have relief and depth. Ways to accomplish this include casting brick and granite into the concrete to enhance its appearance. Architects use windows to enhance designs, including some with openings much larger than normal, making construction more difficult. And integrally colored concrete is being specified more, along with sandblasting, to add color and texture.

Design process

"In the design of tilt-up retail and office buildings, more planning and detail work are required, and there are currently fewer companies interested in building them," observes Glen Doncaster, president of Citadel Contractors, Raleigh, N.C. "Architects are very involved in these projects, and when we, as contractors, get involved with them early in the planning process, we have the opportunity to help them achieve the relief and other effects they're looking for."

Owners with national signature images are beginning to change to tilt-up construction methods, but they want to keep their same building image. This presents new challenges to both the architect and the contractor, requiring innovation and new decorative techniques.

Brick finishes

The Scott System Company, Denver, introduced Brick Snaps for tilt-up construction about 5 years ago. They are precision, standard-sized 1/2-inch-thick brick assembled in individual plastic holders that are "snapped" together on the casting bed in any one of a variety of patterns. The seal between the plastic holders and the brick unit keeps cement paste from leaking through to the face side of the brick. Once the brick is in place, steel reinforcing is added, followed by concrete placed over the assembly, which encapsulates and bonds the brick into the finished wall. The result is a structural tilt-up concrete panel with a traditional brick finish.

Chris Cedergreen, president of Forum Studio, a design firm in St. Louis, reports that it recently completed a building with 50,000 square feet of wall using the Scott System. Installed costs ranged from an additional $6 to $8 per square foot over traditional tilt-up, based on the design requirements. "We're getting very positive results from the public," he adds. "When our first installation was complete, we showed it to our next two clients, who immediately ordered it for their projects."

The Beacon Center, a three-story, loadbearing tilt-up structure in Raleigh, N.C., was recently built using Scott Brick Snaps. Archways in several panels presented special problems because they didn't fit Scott's existing formliner patterns. "We asked Scott to create special soldier-course formliners for the archways," says Greg Heffner, project manager for Centurion Construction, Raleigh, N.C. "Rectangular bricks were still used, but the joints were tapered to fit the arch," Heffner relates. "We also included a 3/4-inch depression at the top of the arch to accommodate a keystone, which we fit into the depression afterward. The keystone projects 1 1/2 inches from the brick face, adding relief to the wall."

Inserting brick elements into horizontally cast-in-place concrete makes it difficult to achieve nicely finished joints. When problems develop with the joints between brick, Doncaster notes, repair is difficult. He is currently experimenting with self-consolidating concrete, which produces clean joints but creates new problems with finishing the concrete on the interior of the panel.

Color, sandblasting, and exposed aggregate

The Site Cast Construction Company is Nepean, Ontario's only tilt-up contractor. Typically, it produces sandwich-cast panels with insulation in the center, which provides the opportunity to build decorative concrete walls. Decorative tilt-up accounts for about 90% of its gross sales. Exposed aggregate is one of its specialty finishes, sometimes with the addition of integral colors. According to vice president Shawn Hickey, Site Cast arranges for an entire elevation of a building to be cast at one time when color is used, ensuring a consistent appearance.