(Chuck Howard, P.E., the owner of Metal Roof Consultants in Cary, N.C., was a metal-roofing contractor for more than 30 years. Much of his work as a contractor was performed for school districts. Howard says school districts' need for long-term durability, while balancing tight budgets, make them an ideal market for metal. The flat roofs used on many school buildings represent an extremely large customer potential for contractors who can convert these roofs to sloped metal, Howard says.
This article explains the benefits of metal for school districts and suggests how metal-roofing contractors can sell district officials on such projects.
Howard says the process worked successfully for him on projects throughout North America.)
As a roofing contractor, you may have heard such pleas from frustrated school officials. The answers are simple: "Yes, you can convert your flat roofs to sloped roofs." "No, it's not too expensive." And, "Yes, there is help available."
Most U.S. school districts have had problems with flat roofs. The majority of the school structures built for the baby boomer generation in the 1950s and 1960s use flat roofs. This type of construction holds water on the surface of the roof, requiring the top membrane to be completely impervious to the infiltration of water through its surface. Whenever this membrane wears out, splits, or is punctured, the infiltration process starts. As many people with a flat roof will testify, once this infiltration process starts, the integrity of the roof membrane, especially with a flat roof, rapidly decreases.
Roof costs studiedA study performed by the Ohio Department of Education indicated that over 20 percent of local schools' infrastructure budgets were spent on roof repair, maintenance and replacement. This category accounted for the highest percentage of all categories surveyed. Similar studies have shown that this situation exists throughout U.S. school systems. It cannot be appreciably improved while the majority of school roofs remain flat, according to many experts.
The solution to this problem is to pitch the roofs. The use of standing-seam metal roofs on these sloped surfaces allows them to last many times longer than other common roofing materials.
They're also cheaper to maintain, according to many experts. A study of eight roof systems done by the American Iron and Steel Institute said that a sloped standing-seam metal roof had the lowest life-cycle cost over a 20-year period.
Almost all school structures are expected to last considerably more than 20 years, making a sloped standing-seam metal roof the least expensive alternative for many schools today.
The stepsConverting a flat roof to sloped metal involves three basic steps:
1. Analyze the existing roof. Figure out its condition. If minor flashing or membrane repairs will not make it usable in the long term, a slope conversion may be necessary. If the roof's structure appears to be adequately supporting the existing flat roof, it should be OK to support the new metal roof and framing. While this assumption will need to be verified by a licensed professional engineer, the original structure is normally capable of the increased dead loads (approximately 2.25 pounds per square foot).
2. Add slope to the flat roof. The slope-conversion process is accomplished by installing a light-gauge steel subframe. This is designed to collect the required design loads and transfer them to the existing structure. Again, this analysis needs to be performed by a licensed professional engineer to ensure that the new composite structure can resist the design loads. The composite consists of the existing roof structure plus the new retrofit framing system. It is critical that the two systems perform as one after the conversion process is complete.
3. Install a standing-seam metal roof. After slope has been created for the roof, install a structural standing-seam roof system, using a concealed fastener to attach the roof panels to the subframe. The roof panels should be at least 24-gauge steel with a Galvalume substrate. This coating system has been in the roofing market since 1972 and field tests show it lasting well beyond its 20-year warranty. In addition, factory coil-coated paints can be applied over the Galvalume substrate to add color to the new roof. These coatings have also been shown to last beyond their 20-year warranties.
As part of the metal-retrofit process, several other parts of the existing flat roof can be improved. First, unfaced blanket insulation can be installed on top of the existing roof membrane, prior to the installation of the new metal-roof membrane. This insulation can dramatically lower the building's energy consumption by providing a much warmer "hat" for it.
Next, the cavity created between the old roof and the new roof can be ventilated. This ventilation process will allow the existing roof membrane to dry without the costly and possibly risky process of removing the roof while the building is being occupied. In addition, ventilation of the cavity will not allow heat buildup in the summer and condensation in the winter.
Working together, this better-insulated and ventilated cavity will greatly reduce heat gain or loss through the roof. This benefit alone often allows the retrofitted metal roof to pay for itself within 10 to 15 years.