About ½ of the roofs I do home inspections on in the Durango/ La Plata area are metal. Metal roofs can be made from a variety of metals and alloys including Galvanized steel — hot-dip zinc galvanized G-90 and G-60 steel (a less expensive, thinner-gauge steel, often used in low-end, lower-cost corrugated and ribbed metal panels), Galvalume steel — zinc and aluminum coated steel (A more expensive and longer lasting coating compared to G-90 steel.), stone-coated steel (G-90 galvanized steel), aluminum, copper, zinc, terne (zinc-tin alloy), and stainless steel.
A metal roof is durable. William Hippard, president of the Metal Roofing Alliance, in Seattle, WA, says the building trades have taken a shine to metal roofing because of its attributes. “Without a doubt, metal roofs are cheaper in the long run,” Hippard says. “Many metal roofs will easily outlast any warranties that the company provides.” Warranties up to 50 years are common, but it’s not unusual to find metal roofing that has been in use successfully for 100 years.
From an appraisal standpoint, Hippard says metal roofs are so durable and desirable that they add approximately $1.45 per square foot to a home’s overall value. Insurance companies give discounts of up to 35 percent to homes with metal roofs because when properly installed they are virtually impervious to wind, hail, and fire.
It is typically possible to install a metal roof over an old roof, thus eliminating the extra cost and hassle associated with the shingle tear-off (be sure to consult your contractor about the possibility of “over-top” installation for your specific roof). — This is generally possible because metal is an extremely light-weight material..
Generally metal roofs require none or minimal maintenance. Metal roofs can be cleaned with water. Almost all of the metal roofs I see during home inspections have some loosened fasteners. This is due to the expansion and contraction of the metal. Our temperatures here in SW Colorado change drastically over a 24-hour period. Corrugated style metal roofs (with exposed fasteners) will require fastener re-tightening every 10-15 years. After years of service, you may choose to repaint a metal roof to give it a fresh look again, but it is not necessary, and will depend on your roof’s original coating.
Metal roofing is the only TRULY green material in the roofing industry, because it uses the least amount of resources during the manufacturing process, contains no petroleum by-products, and can always be recycled. New metal roofs may contain anywhere from 30-60% of recycled metal content, and are 100% recyclable at the end of their service lives. Old metal roofs will never end up in our landfills at the end of their service lives, thus saving the ever-precious landfill space and helping protect the environment. A metal roof (or any metal for that matter) can be recycled an unlimited number of times without suffering material degradation.
During home inspections I am sometimes asked about a metal roof and lightning. A metal roof will not increase the likelihood of your home getting struck by a lightning. If a lightning does strike your home, a metal roof will safely dissipate the electric charge even if it is not grounded. Metal Roofs act as a Faraday Cage for your house and they disperse the charge over a larger area as compared to a skimpy little wire coming down your chimney or wall. They also intercept 100% of the lightning that comes towards your house, unlike a lightning rod which only intercepts the lightning that happens to hit your rod. – You can read more about it here:
Metal roofs shed snow. If you happen to live in an area that often experiences a heavy snow fall, with freezing temperatures, a metal roof will shed off the snow, thus helping prevent a heavy snow accumulation and ice dams on your roof. They shed snow so well that this can be dangerous in places where the roof is on a second or higher story. However, a metal roof can easily be outfitted with snow-guards to prevent the sliding of snow over door entrances and other areas where heavy snow fall is undesirable.