Membrane Roof System Promotes Thermal Efficiency at Athletic Complex
When Radford University, Radford, Va., began considering new roofing options for its 52,000-square-foot Dedmon Center––nicknamed “The Bubble” by students and faculty––energy efficiency, moisture resistance and sound dampening topped the list of priorities. Maintaining the aesthetic appeal and translucency of the athletic facility’s previous single-layer air-supported roof, which was installed in 1981 and outlasted its 20-year expected life cycle by seven years, also was key.
Breakthrough in Fabric Roofing
In the past, insulating tensioned membrane structures only could be achieved through the installation of fabric membrane without any insulative value. Then traditional insulative materials would be installed separately, blocking the natural sunlight. Today, this is no longer the case.
Radford University administrators and their project team chose a composite membrane roof system, consisting of a light insulation layer sandwiched between two layers of fabric membrane. The insulative layer provides an R-value of 12 to the roof and consists of 95 percent air; one 3 mm granule of insulation––a size equivalent to the head of a pin––contains more than 10 billion microscopic holes and more than 1,000 trillion pores, enough to cover an entire NFL football field.
The layer of insulation reduces solar heat gain in warm exterior conditions and retains warmer air in cold exterior conditions, meeting increasingly demanding energy and building codes related to structural-envelope thermal values. In fact, according to recently completed aerial thermal imaging tests, the Dedmon Center’s new roof system has demonstrated thermal performance beyond that of the conventional roof systems already in existence in the structure.
Ease of Installation
Unlike the previous air-supported roof, the Dedmon Center’s new composite membrane roof system is supported by a tri-chord steel truss system. Although the insulated membrane roof system is a new technology, the installation process is similar to that of other fabric membrane roof systems. As with all tensile-roofing applications, partnering with a specialty contractor throughout the design-build process is key to a successful installation. For example, Radford University chose to partner with specialty contractor Birdair, Buffalo, N.Y., to ensure the installation was done by an experienced and knowledgeable design and engineering team.
Retrofit roofing construction on the Dedmon Center began in April 2008 and was completed in January.
- Roofing contractor: Birdair, Buffalo, N.Y., www.birdair.com
- Truss system design: Birdair in conjunction with Geiger Engineers, Suffern, N.Y., www.geigerengineers.com
- Truss fabrication: Superior Steel, Knoxville, Tenn., (865) 522-0253
- Roof manufacturer: Birdair