Whether you are purchasing material yourself or just gathering information for what type of metal roof you are interested in, knowing the pros and cons of the most common types of metal roofing is vital to making an informed choice. As you might imagine, there isn’t a one-size-fits-all solution. So discuss the advantages and disadvantages of each metal with your contractor, distributor, architect or manufacturer before making a final decision.
Modern metal roofs are most commonly made from one of these five materials:
- Stainless steel
There are pros and cons for each.
Introduced in the early 1970s, Galvalume combines three of the most important metals used in roofing today—steel, aluminum and zinc. On the pro side of the ledger, Galvalume offers many pre-painted color options, it is corrosion resistant, is easy to form, 100% recyclable and can be installed over an existing roof. Of course, the number one pro for many Galvalume customers is cost; it is the least-expensive alternative compared to other high-quality metal roofing materials.
Some things to watch out for when using Galvalume include its interaction with other materials. When Galvalume comes into contact with materials such as iron, copper, concrete, bricking and treated lumber, it can result in a galvanic reaction, which can cause corrosion or failure of the Galvalume roof panel. Other cons to this material include the fading of color over time and oil canning, an inherent characteristic of light-gauge, cold-formed metal products. Oil canning appears as waviness or distortion in the flat surfaces of metal wall and roofing products. It is not a structural problem, but some really dislike the appearance. Experienced contractors can use underlayment and other methods to minimize oil canning.
Aluminum is very popular. This long-lasting metal is very lightweight, and it is highly recyclable. In fact, about 95% of all aluminum roofing installed across the world is made from recycled aluminum materials. Readily available (it’s Earth’s third-most abundant element), aluminum has a medium price point compared to the alternatives. One of the biggest selling points of an aluminum roof is the fact that it doesn’t have red rust, and corrosion is generally minimal as it ages. Studies have even shown that aluminum may work great in coastal areas with high rainfall and seawater spray conditions. Aluminum performs better in coastal environments than Galvalume or other steel materials.
Of course, there are drawbacks to consider. A thinner, lightweight material, aluminum has been known to dent easier than other metals. Aluminum also expands and contracts roughly twice as much as a steel roof. This expanding and contracting can also cause oil canning, increased noise and more required maintenance on exposed fasteners.
Zinc roofs have been known to last 60 to 100 years. In some cases, they could even last 150 years. Zinc is an ecofriendly choice as toxicity levels are low even after fabrication. Easy to form, zinc has its own outer protective layer, which prevents against corrosion, scratching and panel markings. If wind or another element were to scratch the surface of a zinc roof, the metal’s protective layer would actually fix and correct itself over time. This can also cut down on maintenance.
Zinc is very expensive to purchase (though it will last decades longer than asphalt roofing and require less maintenance and replacement). Zinc is also susceptible to oil canning and, if improperly coated, can corrode on the underside. Proper ventilation is extremely important with zinc roofs.
Lightweight and energy efficient, copper is a popular choice because of its premium look. It starts as a metallic reddish-brown and ages with a blue-green patina. Durability is also a key feature, as a properly installed copper roof can last 100+ years in some instances. A unique characteristic of copper is that it can be soldered. This means that roof and wall flashings, as well as gutter joints, will be weather-tight with a soldered connection.
Unfortunately, copper is very expensive. In addition, copper roof rain run-off has been known to stain siding, brick, concrete, other metals, wood, etc. Finally, the patina that so many consider beautiful may be a turn-off for others.
Stainless steel is specifically designed to withstand extreme weather and temperature climates. It doesn’t expand or contract due to temperature fluctuations, and it doesn't become brittle or crack during cold temperatures. When temperatures plummet, it keeps the warm air from escaping a structure, and in warm weather it reflects thermal temperatures away from your home.
An expensive option, stainless steel is similar in cost to zinc and copper. Finally, roofing made with stainless steel, especially if it's in contact with other non-stainless steel metals, requires adequate draining methods in order to remain durable and functional. Too much standing water on stainless steel can act as an electrolyte and cause galvanic corrosion of the metal.
Make The Best Choice For YOU
There is not one best material for everyone. Every home, every building, every project is different. From your individual taste to the climate you’re in … from the importance of sustainability to your budget … there are many variables you must consider. The important thing is to discuss your choices in depth with a professional. Whether it’s the manufacturer, architect or a roofing contractor, they can help you choose the best metal roofing material for your specific situation.