It would be an understatement to say that, in the 20 years since the formation of the Tilt-Up Concrete Association (TCA), the construction method has come a long way. In fact, in terms of acceptance, expansion, and innovation, tilt-up construction—the method by which concrete elements are cast on-site and lifted into place—has made monumental gains.
But tilt-up did not appear in just the last 20 years. The origins of tilt-up can be traced back to a 1903 quote by Thomas Edison “Tilt-up construction eliminates the costly, cumbersome practice of erecting two wooden walls to get one concrete wall.” On today's tilt-up projects, contractors regularly deliver much more than just concrete walls. Robert Aiken, widely considered the father of tilt-up, began using this method around the turn of the 20th century. The Zion United Methodist Church, Zion, Ill., was constructed by Aiken in 1918, and stands today as a testament to the strength and durability of the tilt-up method.
The growth of tilt-up
Tilt-up was once thought of primarily as a solution for industrial needs. However, these warehouse and big-box construction projects eventually sparked an interest by adding architectural details.
“The really big boxes of 500,000 square feet and above established tilt-up as the economical way to build,” says David Kelly, vice president and chief engineer, Meadow Burke, Sacramento, Calif. “Contractors and developers, in their effort to diversify and expand their market, got architects to dress up the appearance. My recollection is that the architectural upgrades began with dressing up offices in front of warehouses or industrial plants, and then progressed to stand-alone office buildings.”
Architectural variety has grown through the use of reveals and recesses, larger and more complicated openings, massing and overlapping of panels, cast-in materials like thin-brick, and integral coloring to enhance exposed aggregate methods. This level of creativity was once thought impossible to achieve with tilt-up, yet today's market shows just how commonplace up-scale tilt-up buildings have become.
“I have found it interesting to see how creative designers have become with the medium over the years,” says Dave Prizio, president of Prizio Construction, Santa Ana, Calif. “They are constantly pushing the envelope and challenging contractors with innovative designs.” The increase in architectural options has caught the eye of many retailers, who realize tilt-up provides not only a cost-effective construction solution, but also a means to promote their unique brand identity.
Cost-effectiveness and aesthetic possibilities—not to mention time savings and durability— have made tilt-up an attractive option to many other owners, dispelling the myth that the tilt-up domain is only warehouses and big-box retailers. Religious organizations, schools, theaters, and hospitals are now beginning to turn to tilt-up as a preferred method of construction.
“A school official recently told me that their district is willing to pay more for tilt-up structures because of the durability it provides,” says Clay Fischer, president, Woodland Construction, Jupiter, Fla. “This is a remarkable achievement, because just a few years ago there were not many tilt-up schools, and now school districts are demanding it.”
Tilt-up contractors have also begun to experiment with a variety of panel sizes, erecting everything from panels reaching nearly 100 feet in height to smaller panels necessary for structures such as concrete homes. Reducing tilt-up's limitations has broadened the method's reach, encompassing structures that were once considered impossible to build via tilt-up construction.
“Tilt-up's acceptance and ‘request status' has expanded into building types once considered the exclusive territory of more ‘up-scale' construction systems,” observes Glen Stephens, president, Stephens Architectural Associates, Laurel, Md. “Today, more and more construction-savvy architects are cognizant of the new and unique design possibilities only available with a tilt-up solution. It is pre-cast without limits.”
It's not just architects who are responding to the growth in tilt-up. The industry as a whole has recognized its momentum, and suppliers are continually offering new products and services—such as architectural treatments, finishes, panel-edge adhesives, and new braces and cranes designed to support larger panels—that will help further extend the possibilities of tilt-up.
“This kind of attention from suppliers to the industry and the requisite R & D will lead to ever more innovation in building, design, shortened schedules, and cost reduction that will confirm tilt-up as the standard to which others are held,” predicts Bob Thiesen, formerly of Tilt-Pro.
Jim Baty, technical director for the TCA, expects certification to play an important role in future growth. The joint TCA/ACI certification program, developed through ACI's Committee C650 to provide measurable quality assurance, was created in 2001 in response to the rapid growth the construction method had experienced. More than 800 certifications have been issued since the program's inception. Today an increasing number of contractors are seeking initial certification, and a significant number of individuals will need to be re-certified over the next few years.
Certification requires knowledge in safety, plan reading, scheduling, site preparation and foundations, slabs on grade, layout, forming, placement and properties, erection, and structural systems. Those achieving a passing score (70%) on the 80 multiple-choice question exam become certified as Tilt-Up Technicians.
Attaining the status of Tilt-Up Supervisor requires a minimum of five years (7500 hours) of verifiable construction experience, of which at least three years (4500 hours) must have been as a tilt-up supervisor or assistant supervisor. It also requires a demonstrated proficiency in, and an understanding of, overall onsite administrative and technical management for producing tilt-up projects. Those certified hold the status for five years before having to re-certify by successfully completing the current requirements for certification. A certified technician can upgrade to a certified supervisor status at anytime within a five-year time period of their certification through the completion of the necessary work experience.
According to Baty, in certain areas of the United States and Canada, specifications are requiring certified personnel on their construction team. One such area is in Florida. Fischer has had several proposals come across his desk that require certified personnel on the job.
“In the past few years, I have seen the certification requirement in nearly 25 proposals,” Fischer said.
“Certification benefits the entire industry by creating a method for quality assurance. At our company, it is mandatory for supervisors to be certified.” Certification was required on the 33,000-square-foot Palm Beach International Airport Administration Building in West Palm Beach, Fla. Tilt-up was selected for this administration and communication center because of the building's ability to withstand hurricane-force winds. The architect for the project believed that they would receive a higher caliber of quality control by using certified contractors.
Examples of projects requiring certification can also be found in Nova Scotia, Canada. Laurence Smith, project manager at J.W. Lindsay Enterprises Ltd., Dartmouth, Nova Scotia, explains that the Department of Transportation and Public Works for the province of Nova Scotia has required the use of ACI-certified personnel on several projects, including schools ranging from 65,000-square-foot middle and junior high schools to 125,000-square-foot high schools. “Throughout Nova Scotia, tilt-up has been used on more than 30 schools since 1997,” Smith said. “More recently, the Department of Transportation and Public Works has employed tilt-up construction for hospitals and nursing homes. As a result of provincial usage, the local municipalities have gravitated to tilt-up for community centers and fire halls.”
Also, there is a recently formed seismic design task group in response to concerns about a lack of tilt-up-specific design guidance for structures in high seismic regions. The task group plans to develop solutions for dynamic modeling through the National Earthquake Hazard Reduction Program (NEHRP) and propose detailing through the American Concrete Institute (ACI). The group will concentrate on several key issues: loads applied to panels, details for connections, panel design, adjustments to the current concrete code, classification of flexible diaphragms, and recognition of the increasing number of tilt-up buildings that reduce the flexible diaphragm characteristic by bracing the frame due to complex façade perimeters.
The next 20 years
If tilt-up continues to spread as it has during the past 20 years, there's no doubt that the future will be bright. From 1995 to 2000 alone, tilt-up construction grew by more than 111%, and it shows no signs of slowing. As more companies rush to provide specialty products for this market, the possibilities for tilt-up projects will continue to grow. Emerging issues, such as green building and sustainability, will undoubtedly frame tilt-up as a viable option for achieving newer, tougher design standards. In the face of natural disasters, owners will also likely turn to tilt-up because of the proven durability it provides.
Last year marked a new record for tilt-up construction sales in the United States. More than 753 million square feet of buildings were constructed using tilt-up in 2005, up from approximately 664 million square feet in 2004. That translates to approximately 301 million square feet of wall panels in 2005, compared to approximately 265 million square feet the previous year, for an industry growth rate of 13%.*
“Exposure of what is possible with tilt-up today is clearly shown in the diversity of architectural expression and quality of projects submitted as part of the Tilt-Up Achievement Awards competition each year,” said TCA executive director Ed Sauter. “The growth of site-cast tilt-up construction as a preferred building method will continue to grow as more and more owners are exposed to the benefits.”
“I don't think it's done (maturing) yet,” says Michael Sugrue, principal of LJB. “It's amazing that the skeptics of yesterday are now the proponents of today.”
Smith explains that the current boundaries that are being broken are building size. “The use and implementation of tilt-up is becoming so prolific that it is the preferred method of construction for commercial and industrial buildings,” Smith said. “Buildings as small as 3000 square feet are now being economically done and 6000 to 15,000 square feet are routine.”
Expecting higher energy costs in the future, building owners and operators are putting more value in a better building system. Smith contends that in the next several years, as the concept of smaller buildings is not only perfected but also accepted, it will eventually lead to residential construction. “We are seeing bits of residential tilt-up now, but need to tune the system with the finishes to gain widespread acceptance,” he said. “Nowhere does the cost of operating a building hit home harder than at home.”
Sauter looks forward to the future of tilt-up as well. “It's a great time to be involved in the tilt-up industry,” he says. “Exciting things are happening on a daily basis. Each year, as I review the TCA's building award submittals, I remark that it can't get any better than this—and each year, I'm proven wrong.”
* The annual growth rate is based on sales of lifting inserts as reported by the major manufacturers of tilt-up accessories. Lifting inserts are designed for a given thickness of panel and have a maximum lifting capacity. Using a series of calculations that account for under-utilization and other factors, the total square foot of panels lifted, based on the connectors sold, is calculated. Then, using an industry-accepted ratio for low-rise buildings of wall-to-floor area of 0.40, the square feet of floor area enclosed by tilt-up wall construction is estimated.
— Wendy O'Bryan Ward, vice president, and Clare Martin, editorial manager, are with Constructive Communication, Inc., a marketing/communications and media relations firm specializing in technical and professional services firms.