Tilt-Up Finishes First in School Construction Comparison
By: Kimberly Kayler
Constructive Communication, Inc.
The construction of two new elementary schools by the Leander Independent School District (LISD) in Texas gives new meaning to academic competition. Each is being built using a different construction method, and the race is on for project success.
According to Tim Cahalane, Project Director for American Constructors, Inc. of Austin, in 2007, LISD unveiled a new design for its elementary schools – the product of a design review process and charette that began in 2006 and included the efforts of educators, stakeholders, construction managers and architects.
“The district realized that today’s K-12 educational facilities, in particular the elementary grades, require high-performance design to enhance the learning environment,” said Cahalane. “Since school facilities have a profound impact on their occupants and the function of the building, LISD wanted to create a collaborative school environment where everyone shares the same vision of success. As such, LISD used an integrated design approach and team process. The stakeholders worked together throughout the project phases to evaluate the design for cost, quality of life, instruction, future flexibility, and efficiency. Building systems were selected on the basis of life-cycle cost analysis, balancing initial design and construction cost, while providing LISD a building that complements both the District and the community values, allowing form to follow function.”
A NEW MODEL OF SUCCESS
According to the District’s new model, buildings are now to be designed around LISD’s learning model, which includes making extensive use of natural light in all common areas and improved flexibility so teachers can easily shift between whole group and small instruction or collaborate with other teachers. Classrooms are clustered around neighborhood areas. The new design incorporates sinks and other resources built into classrooms to eliminate long trips down hallways to access areas like science labs, as well as strategically placed common areas adjacent to classrooms with good transparency between the spaces. Further, the design eliminates the long hallways common in typical school designs, resulting in classrooms with L-shaped configurations and more corners for small group instruction.
Building on these design themes, in 2007, LISD selected two separate architect/construction manager teams for elementary schools #20 and #21. Both are 110,000-square-feet in size and were on schedule to open in fall 2008. Each project contains the same basic floor plan, educational programming, as well as Mechanical/ Electrical/Plumbing (MEP) system. However, the teams were allowed the flexibility to select their structural and exterior skin system. The design/ construction team for #20 selected a traditional block/brick and steel construction approach, while the team for #21 selected site-cast Tilt-Up construction.
A NEW, YET PROVEN SOLUTION
A longtime solution for durable and maintenance-free facilities in the commercial and industrial sector,
the growth of architectural treatments, formliners and even cast-in brick products has allowed Tilt-Up
to compete with the traditional school material of choice – masonry. Athletic facilities, modern meeting spaces and assembly areas also are a must – all easily accommodated with the site cast Tilt-Up concrete method of construction.
Cahalane’s company is on the team for School #21. Building on experience constructing four elementary, two middle and two high schools for the District, all Tilt-Up, he stated that this team selected the construction method because it takes advantage of the inherent flexibility of a unique, well proportioned blend of building massing, color, texture and articulation.
“Since our initial Tilt-Up projects for the District, thermal image results have proven the benefit of concrete Tilt-Up walls with integrated insulation as compared to masonry in terms of energy efficiency and lower operating costs,” said Cahalane. “Based on our knowledge that Tilt-Up could meet all the parameters established by the design and process team, we felt confident recommending the building system.”
Cahalane said Tilt-Up concrete enables durability, flexibility as well as cost and schedule control. But, design was not sacrificed for the sake of budget and schedule. Key elements of the design include the use of a blend of inlay thin brick and natural concrete with coating colors offset by reveals for an attractive and consistent response to the environment. The design team utilized interior structural Tilt-Up components to further minimize masonry and steel, which resulted in cost and schedule savings. With fewer interior columns than other building methods, Tilt-Up enables functional cluster rooms around common areas, connects spaces visually, provides gathering spaces, and allows classrooms to change with the activity and group size. Of the 205 total Tilt-Up panels on the project, 92 are interior utilized at the elevator, fire separation walls, gym and corridor wall. The learning centers were offset at 45 degrees from the main building to maximize natural lighting and visual effect. Further, Tilt-Up provides interior environments that are visually comfortable and incorporate natural and artificial light.
Tilt-Up also provides the desired acoustical and indoor air quality environment as well as ensures thermal comfort. Also, Tilt-Up uses sustainable materials since processes and materials could be manufactured locally, which was attractive to LISD. Durability also was a key concern for the school district and Tilt-Up decreases the risk of mold and efflorescence with early dry-in and elimination of exterior air cavities.
ENGINEERING EXCELLENCE
While the construction team has touted success using Tilt-Up, the structural engineering firm on the project also shared insight on why the method is beneficial for schools. According to Gary Pickett, P.E. of Pickett, Kelm & Associates, Inc. of Austin, the combination of exterior and interior load-bearing Tilt-Up walls eliminated the need for exterior columns and minimized interior column requirements, which maximized the project architect’s flexibility to design and lay out interior spaces.
“With Tilt-Up,” said Pickett, “interior finish walls are clean, smooth, durable and free of bump-outs and pilasters. Also, the use of interior load-bearing Tilt-Up allowed us to provide a very high level of structural framing efficiency. Because the interior Tilt-Up panels provided long, continuous lines of support, we were able improve structural economy by maximizing deck spans and providing regular, repetitive floor beam and roof joist sizes, spacings and details.” Pickett added that by utilizing the Tilt-Up method’s inherent lateral load resistance, they were able to eliminate the need for braced or moment-resistant steel frames by using the wall panels as shear walls. Further, speed of construction, an important consideration for this project, was improved due to construction of the wall system at ground level, a reduction in the number and coordination of trades, the elimination of the need for scaffolding and the combination of structural and architectural elements. Dry-in of the building was accomplished quickly.
“In addition to the structural design and speed of construction advantages, the exterior insulated Tilt-Up panels provide a superior building envelope,” Pickett said. “Water tightness is excellent due to a reduced reliance on joints, sealants, caulks, multiple components and elaborate details. Tilt-Up allowed the design and construction teams to combine these advantages with a high level of energy efficiency to deliver a functional, durable and very attractive educational facility within a compressed construction schedule.”
THE PROOF IS IN THE NUMBERS
In addition to meeting functional and aesthetic goals, as well as a tight schedule, long-term cost efficiency is key to LISD. With regard to the budget, Cahalane stated that, based on life cycle costs, Tilt-Up enables the District to optimize energy performance, and the structures are easy-to-maintain. Construction began October 2007 and the owner met their target dates for moving in furniture and staff this summer. And, the occupancy permit was received in early August, in time for the Aug. 25 start of the school year.
Cahalane stated that the Tilt-Up project cost six percent less than the masonry project for the same configuration and floor plan including MEP and interior systems. Virtually all components are identical with the exception of the structural and exterior and interior walls which are either Tilt-Up or masonry, he said. In order to maintain a comparable schedule during the early structural phase, approximately three times the masonry labor force was required as compared to the Tilt-Up project.
According to Cahalane, the district views this as an opportunity to evaluate the two systems and they will perform a cost, performance and energy analysis. They will perform a total system analysis prior to beginning construction of other new schools.
“Tilt-Up was able to meet the District’s challenge to build a high quality school in order to fulfill current demand with the optimal design,” said Cahalane. “To achieve a high performance building, the form must follow the function and include aesthetics, operation, air quality and cost effectiveness.”
According to Jim Baty, Technical Director for the Tilt-Up Concrete Association (TCA) – a non-profit international organization that serves to expand and improve the use of Tilt-Up as the preferred construction method – the use of Tilt-Up is a growing solution to meet today’s education needs and this project is a perfect example of this growth.
“Those benefiting from the school construction boom are the designers and contractors that have the ability to provide long-term, durable and safe solutions for our nation’s classrooms under tight construction schedules – and site-cast Tilt-Up can meet these needs,” said Baty.
“Site cast Tilt-Up construction also is experiencing a rapid expansion, both in actual use and architectural treatments. This parallel growth, as well as the adaptation of design-build for schools and new architectural products, makes Tilt-Up an A+ choice for school boards and private communities.”
