In the arena of retail construction, time and creativity are equally paramount. Failure to meet a proposed deadline simply is not an option. A delay in a store opening may result in missing a busy shopping season or the launch of a new product line. In addition, many retail construction contracts have stiff penalty clauses for missed deadlines that can be costly to both the general contractor and the developer. But the retail industry also is extremely conscious of its image. Stores must be modern and support a company's corporate identity. In recent years, site-cast tilt-up has become the method of choice for this industry because of its proven ability to deliver on both fronts. Tilt-up not only affords owners a fast-track construction schedule, but a variety of architectural options and rich aesthetic appeal.
“Getting people into a store more quickly and for less money so profits can be realized more easily—that's the target for today's retailer,” says Jim Baty, technical director of the Tilt-Up Concrete Association (TCA), Mount Vernon, Iowa. “The ability of tilt-up to dramatically reduce construction time and to do so on reduced budgets ultimately delivers the type of project that retailers seek the most. In addition, tilt-up has the potential to deliver an iconic final product in virtually every project.”
Floor mix designs
A high-quality floor often is used for the casting surface, which means that the retailer receives the benefit of an exceptional floor for the operation of the facility. In addition, this floor is ready for a variety of treatments or services.
Floor mix designs have many considerations and achieving flatness is the most important element. Glenn Doncaster of Citadel Contractors, Apex, N.C., notes that a 3000- or 3500-psi mix design, with a water-cement ratio of 0.5 or below and a 4- to 5-inch slump, is desirable because it reduces shrinking and provides enough paste for finishing operations. “For floors that will have coverings, such as carpet or tile, we use 4/4/4/4* wire in the top third with no sawcuts. The floor should be very flat with no curl except at the edges,” says Doncaster. “Special attention must be paid to retail tenants' prototypical requirements, because some retail floors use concrete as the finished product and require specific construction techniques.”
According to Doncaster, panel fabrication may start three to four weeks before erection. “However, for the majority of the project, panel erection and fabrication occur simultaneously,” he says. “Beam testing for panels is highly recommended when cycle time is down to four days or less.” For a multitenant site, most panels are lifted from the exterior using a crawler crane, which allows for reuse of casting beds and surfaces.
Doncaster explains that mix designs for tilt-up panels typically have a water-cement ratio of 0.5 or below. “Tilt-up panels use a high-range water reducer to achieve an 8-inch slump, which creates a clean, crisp, and durable panel face. This is important for retail facilities that desire an aesthetically pleasing building and can show off any architectural features.” Panel thickness typically is engineered for the large openings required in retail projects. “Panel thickness can range from 8 to 16 inches,” says Doncaster.
Although traditional warehouse-style tilt-up construction has long been favored by big-box retailers, smaller tilt-up structures with more distinctive architectural features are beginning to show up in lifestyle shopping centers—which, according to the International Council of Shopping Centers, are one of the fastest-growing trends in the retail industry.
“When it comes to lifestyle malls, the features are the main characteristic,” Baty says. “Creating a village atmosphere is a key to the lifestyle mall, where facades are greatly varied and the scale of the project at the streetscape is broken down to a more personable level. Achieving this on a schedule that facilitates the interests of retailers is virtually limited to tilt-up as a delivery method.”
Tilt-up construction appeals to the retail industry for a number of reasons, ranging from aesthetic flexibility to the ability to respond to the needs of mixed-use structures. A number of projects throughout the country have benefited from tilt-up's unique attributes.
Flexible construction method. Tilt-up's ability to provide architectural flexibility on a tight schedule was a boon to the developers of the Winter Garden Village retail center in Winter Park, Fla. With more than 500,000 square feet of retail space scheduled to be built in a 10-month period, the developers decided to scrap the original plans for concrete masonry construction in favor of tilt-up to accommodate the aggressive schedule. To replicate the proposed masonry appearance, thin brick was applied using a molded form-liner. To get around site limitations—a common challenge in lifestyle center tilt-up projects—the contractor reused the casting beds several times.
Building with limited space. Stack casting, in which multiple panels are cast on top of one another on a single casting bed, also is a popular way to deal with site limitations while maximizing schedule efficiency. This casting method was used by contractors at Metropolitan at Midtown, a high-end lifestyle center in a revitalized area of downtown Charlotte, N.C. The contractor accommodated a fast-track construction schedule and worked around concurrent construction on the site. This project was completed in two phases: The panels for the Target and Home Depot stores were stack-cast during the first phase, and panels for Marshalls, Best Buy, and Staples were stack-cast during Phase II. Despite the schedule and accessibility constraints, the project's designers were able to give the shopping center an upscale look—desired not only by the developer, but mandated by city guidelines—with thin brick veneers, linear reveals, aluminum sunshades, decorative concrete sidewalks, and large storefront windows.
Mixed-use applications. Because of its versatility, tilt-up has the ability to serve as the primary construction method for another growing trend: mixed-use developments that blend stores with residential and office space. The Marketplace at Lake Boone, a mixed-use retail, restaurant, and office development in Raleigh, N.C., presented a major challenge: Occupancy time frames meant that detailed project scheduling and staging of multiple buildings were necessary to meet the critical dates for the beginning of tenant up-fits and the completion of the surrounding sitework. The project featured a range of unique design elements, including multilevel balconies, arched openings, cupolas, and detailed fenestration. EIFS ornamentation—a popular architectural treatment for tilt-up structures—was applied to cornices, while spandrel glass, tilt-up columns, curved panels, and metal treatments were used throughout the structures to further boost architectural interest.
Sustainable building techniques. Going green is moving to the top of many retailers' priority lists. A 2008 study by the National Marketing Institute found that 19% of North American consumers embrace a healthy, sustainable lifestyle, and retailers are seeking to reach out to this growing market segment by demonstrating a commitment to sustainability. “Site-cast tilt-up is one of the greenest building materials out there, due to its energy performance and local material utilization,” says Baty. In addition to the durability and energy retention that make the concrete itself sustainable, tilt-up buildings can be easily integrated with other energy-saving features. According to Baty, tilt-up provides a durable energy-efficient shell, which helps manage the large temperature swings that can occur with high-volume traffic that is common in retail outlets.
Due to its origins as the construction method of choice for big-box warehouses, tilt-up has long had a reputation for only being able to support large, simple structures. But the range of creative retail projects built today proves that this is not the case. Even with specialized architectural treatments applied to today's structures, tilt-up manages to retain its time- and cost-effectiveness.
As more retail tilt-up projects appear, the construction method's ability to meet the retail industry's demand for creative structures with a quick turnaround will only continue to gain momentum. “By exploring the ways the current state-of-the-art tilt-up construction is delivered ahead of schedule and under budget, the retail market can be better informed and better prepared to make the decision earlier to select tilt-up,” says Baty.
* 4/4/4/4 indicates a 4-gauge wire, each direction, in a 4x4-inch pattern. In residential construction, a 6/6-10/10 often is used, which is a 6-inch grid of 10-gauge wire. Most wire reinforcement these days is specified using the W number in inch-pound units or the MW number in metric. The Wire Reinforcement Institute has tables showing equivalencies for all these designations. Download the WRI document TF 208-R-08 atwww.wirereinforcementinstitute.org.