Metal Proves to Be an Appropriate Substrate for Retrofitting a DoD Test Roof
The U.S. Department of Defense (DoD), Washington, D.C., manages more than 500,000 buildings and structures. It also is the single largest energy consumer in the U.S.
DoD’s Environmental Security Technologies Certification Program (ESTCP) provides grants to industry to demonstrate commercially available and sustainable novel technologies, products and systems aimed at meeting DoD’s energy- and water-conservation goals. ESTCP recognizes the military must find systems and technologies whose performance can be demonstrated and then transferred to any building in DoD’s inventory. A grant to achieve this with integrated metal roofing technology on Goodfellow Air Force Base, San Angelo, Texas, was awarded in 2011. The new metal-over-metal retrofit roof integrates cool roofing, solar-power generation, solar thermal, rainwater catchment and above-sheathing ventilation in one holistic system that is being monitored by Oak Ridge National Laboratory, Oak Ridge, Tenn.
Metal Roofing Benefits
The word “steel” conjures images of strength and durability. Steel is used in highway and bridge construction for its strength. Steel is used in cars for safety. Steel is used in the military for its ability to protect our service men and women. Steel also can be used in residential and commercial roofing in a light flat-rolled configuration. The reasons are the same as for other uses: It is strong; light weight; non-combustible; resistant to hail, wind and weather; and features almost unlimited aesthetics and design flexibility.
For decades, our nation’s military has used metal roofing for new construction, reroofing and retrofit projects. In fact, DoD’s “Base Structure Report” estimates more than 1.85 million square feet of metal roof retrofits have been installed on military and federal facilities in the U.S. It is further suggested that another 617 million square feet of single-story military buildings will receive metal roof retrofitting.
Military buildings with roofs more than 25-years old generally need new roofs and insulation, ventilation and rainwater/ drainage improvements to meet current building standards. New mandates for saving energy, producing energy at lower cost and establishing independence from the grid also must be considered. This is no small task, but integrated systems may be the answer for energy savings and greatest design flexibility.
The nature of a holistic, integrated metal roof retrofit option led to ESTCP’s selection of a metal-retrofit demonstration project at Goodfellow AFB. The project involves an existing metal roof retrofitted with a new 24-gauge prepainted Galvalume steel standing-seam roof system.
Standing-seam steel roofing is created with roof panels that are mechanically interlocked together with a mastic in the seam joint to provide a watertight roof system. The attachment clips are concealed but mechanically attached to the substructure of the building framing, meeting all building-code requirements for design loads and resistance to wind uplift.