Metal roofing is gaining in popularity across the country for its longevity. Most roofing metals are also resilient enough to resist damage from common Oklahoma hazards, such as falling tree limbs, hail, and high winds. Since metal doesn't burn, it's especially appropriate for businesses close to areas at risk for wildfires or located far from a fire station. Following are some facts about the five types of metal used in roofing materials.
Aluminum - Requiring little maintenance and highly resistant to corrosion, aluminum has increasingly become the roofing material of choice for customers seeking longevity. In a hot climate like Oklahoma, aluminum can be a wise choice as it reflects heat much better than steel, thereby keeping a business cooler and lowering air conditioning costs overall. A properly installed aluminum roof will last approximately 35 years.
Copper - Copper isn’t widely used as a roofing material currently, though it's by far the longest-lasting of all roofing materials. In many European countries, one can find penny metal covers that have been reliably performing for hundreds of years, and are estimated to last for several hundred more. Copper’s downside is that it is increasingly rare and therefore quite expensive.
Galvanized Steel - This material is made of alloyed steel with a protective coating of zinc, rendering it highly rust resistant. The resilient qualities of galvanized steel can be enhanced with a zinc-dust type paint. Cement-based and latex coatings may also be used, but make sure they are formulated specifically for galvanized steel. Do not use aluminum-based finishes. Bare and painted galvanized steel are recommended for use with concrete or stone buildings, as it will not corrode in reaction to these highly alkaline materials. With proper maintenance, galvanized steel is an inexpensive roofing material that will last 60 years or more.
Galvalume - This is a relatively new material developed by Bethlehem Steel in 1972. Comprised of steel coil coated with metal alloy, it is finer grained and smoother in appearance than galvanized steel. It can be more rust resistant than galvanized steel, however because its protection comes from barrier rather than galvanization, it can rust easier around scratches and cut edges. However, Galvalume should not be used on buildings where it will be in contact with concrete or mortar. These materials are highly alkaline and will cause the sheets to suffer rapid corrosion. Also Galvalume should also not be used for animal confinement operations, as the gasses emitted are corrosive.
Tin, Terne or Terneplate - Any one of several soft metal materials that have been treated with a lead and tin coating. A properly installed tin roof can last between 40 and 50 years. Thomas Jefferson’s Virginia home, Monticello, still sports its original tin roof, without any signs yet of catastrophic wear.
All metal roofs require an “accessory”, grounding. As metal roofs are great conductors of electricity, they conduct the electricity of lightning, which is common with Oklahoma’s frequent thunderstorms. Grounding provides a path for the lightning’s electrical current, enabling it to bypass the house and harmlessly enter the earth. Without proper grounding, your home’s electrical system can possibly absorb the charge, which can lead to fire or personal injury.