of warranties for metal roofs and walls. For example, paint-finish warranties can vary from five to 50 years and my reference specific film integrity, chalk and fade. There even is a 25-year perforation warranty for unpainted Galvalume. Standing-seam roof systems that carry a weathertightness warranty, which can range fro five to 25 years, guarantee the roof will not leak.
Regardless of the types, all warranties have maintenance requirements. Each warranty carries a caveat about cleaning the roof annually. Each warranty carries a caveat about cleaning the roof annually. Maintenance does play an important role. It is necessary from a warranty standpoint and also is vital in achieving the optimal performance of any building.
Keep It Clean
Every metal-panel manufacturer has maintenance guidelines for its products, despite whether those products have a warranty. In addition to basic maintenance instructions, there often are instructions for maintenance during installation. For example, instructions typically advise keeping the panels clean of metal shavings and cuttings created when fasteners are frilled through the panels and substrate or through the panels and trim being field-cut to meet installation requirements.
The rusting process takes only 12 hours of exposure, so it is critical the panels be cleaned of all debris at the end of each work day during installation. Although aluminum shavings will not rust, they still must be removed to keep the paint finish from being scratched. The installer needs to remove the shavings from the gutters and downspouts, as well, because building-up in these places will accelerate the rusting process on the water-collection side of the gutter.
A metal-clad building can last longer if it has a properly maintained, strict maintenance program.
When the project is complete and turned over to the owner, it then is his or her responsibility to maintain the building’s exterior to achieve a longer building life. A properly maintained metal-clad building can last more that 40 years.
At the very least, the owner should set up an annual maintenance and inspection schedule that includes walking around the perimeter of the building and removing any loose debris, such as branches and tree leaves; cleaning the gutters and downspouts; and washing the roof when necessary with a solution of water and 5 percent commercial or industrial detergent.
Maintenance is necessary from a warranty standpoint and also is vital in achieving the optimal performance of any building.
Metal wall panels should be inspected for loose or missing fasteners or exposed caulking throughout their life. It also is advisable to remove any mud, dirt and mulch from contact with the wall panels. In addition, the building should be inspected after each major wind or storm event. These events generally involve flying debris that can damage and stain a building’s metal cladding.
Keep It Cool
One of the hot topics today involves the green qualities and energy efficiency of metal walls and roofs. One area that has gotten a great deal of attention is cool roofs. A cool roof reflects the sun’s heat and emits absorbed radiation into the atmosphere. The roof stays cooler and reduces the amount of heat transferred to the building interior. Less energy is required for cooling.
According to the Oakland, Calif.-based Cool Roof Rating Council, the two basic characteristics that determine the coolness of a roof are solar reflectance and thermal emittance. Both properties are rated on a scale from 0 to 1 with 1 being the most reflective and emissive.
In the past, it almost has been impossible to offer darker cool colors. In recent years, however, paint manufactures have introduced cool-paint pigmentation, which enables darker colors to offer improved solar reflectance and thermal emittance values while still maintaining their dark colors. This advancement has brought greens, blues, and browns into the cool-color world.
On a smaller project, like a house, the average savings range from 7 to 15 percent in total cooling costs. On larger projects, such as schools with more expansive roof areas, there can be as much as a 40 percent savings in the utility bills of a project that has a cool roof. However, the build-up of dirt and debris can block sunlight and impair the roof’s reflectivity, so it is important to keep the roof properly cleaned and maintained.
No matter what the project is, there must be an active preventative maintenance program performed on the building envelope for the building to function to its fullest potential and deliver all the benefits an efficient metal roof, wall or building system can offer.
Dave Fulton is vice president of research and development for a metal-building and –component manufacturer. He is on the board of directors for the Pittsburgh-based Cool Metal Roofing Coalition and holds several U.S. patents related to the metal industry.