metal roof, July/Aug 2020

Light-gray metal roofing keeps this cozy cottage cool in summer. Similar to shown: 5V-Crimp Galvalume Plus panels, $1.30 per square foot; McElroy Metal | Nancy J. McGregor

It’s hard to top the versatile looks, longevity, and peace of mind that come with a roof made of metal. Read this guide to learn what you need to know before putting one on your own home.

The advantages of metal roofs are tough to ignore. They’re strong, able to survive hurricanes, hail, and wildfires. They’re durable, enjoying a life span of up to 50 years or more. They can save energy, thanks to their ability to reflect the sun’s heat. And properly installed, they need virtually no upkeep.

In America, copper and lead roofs appeared on important public buildings beginning in the 18th century, including New York’s City Hall in 1764. By the mid-1800s, metal roofing became more common as mass-produced steel began covering ordinary homes and barns. By the 1920s, lightweight, no-rust aluminum entered the market, as did paint coatings that added color and longevity to both aluminum and steel roofs.

Today, metal roofing is on the rise again: Its popularity has nearly quadrupled in the last 20 years. And while it commands a premium—the components are expensive, as is the skilled labor for installation—a metal roof can boost a home’s resale value by up to 6 percent in some areas. Up ahead: a look at materials and styles to consider, plus how to get the job done right, so your house will stay cool and dry for decades to come.

Favored by a Founding Father

metal roof: Thomas Jefferson Foundation at Monticello, July/Aug 2020
Courtesy Thomas Jefferson Foundation at Monticello


In 1824, Thomas Jefferson replaced the original wood shingles on Monticello’s roof with ones made of terne, a tin-coated iron; they lasted until 1855. After a succession of inferior, leak-prone substitutes, the roof regained its 1824 look in 1992 with the installation of terne shingles made of tin-coated stainless steel.

Costs & Durability of Metal Roofs

installing a metal roof, July/Aug 2020
Courtesy Drexel Metals

What do metal roofs cost?

Installed, metal roofs run $7 to $20 per square foot, depending on the type of metal used. That’s two to six times the cost of an asphalt roof.

How long do metal roofs last?

On average, they have a 40- to 70-year life span, depending on the type of metal used, the harshness of the local climate, and the skill of the installer.

Are they noisy?

Properly installed over plywood sheathing and the recommended underlayment, a metal roof isn’t noticeably louder during a rainstorm than one made of asphalt (52 decibels versus 46).

What’s the warranty?

Most makers guarantee the products for as long as you own your house, and allow the warranty to be transferred to the next owner.

Material Choices

Every metal has its pluses, whether it’s durability, color, or cost. Choose the one that suits your climate and your budget, and that will enhance the style of your house.

1. Steel

steel metal roof, July/Aug 2020

This is the strongest, most popular, and, typically, least expensive option. To prevent rust, it’s usually dipped in molten zinc (making galvanized steel) or an aluminum-zinc alloy called Galvalume. Dipped steel can be left in a silvery state, but is generally painted to maximize longevity. Can last 30 to 50 years.

2. Aluminum

aluminum metal roof, July/Aug 2020

Lighter, softer, and pricier than steel, aluminum comes in many of the same embossed styles; under a coat of paint—aluminum is almost always painted—it’s hard to tell the two metals apart. Aluminum is a good choice in areas with salt air or acid rain since it doesn’t rust. Can last 30 to 50 years.

Copper

copper metal roof, July/Aug 2020
Courtesy Future Roof Systems

The oldest, longest lasting, and most expensive metal for roofs, copper is easy to cut and shape. Uncoated, its bright, gleaming shine quickly acquires a protective brown patina that can turn a soft blue-green over time. Unlike other metals, which are specified by thickness, or gauge, roofing copper is specified by its per-square-foot weight in ounces. Can last up to 200 years.

4. Terne

terne metal roof, July/Aug 2020
Courtesy Fine Metal Roof Tech

The original tin-and-lead-coated roof, used in Europe in the 18th century, it was often painted to protect its iron substrate. Today’s lead-free version—stainless steel sandwiched between layers of tin—naturally resists the harshest conditions, never needs paint, and weathers to a uniform matte gray. Can last more than 100 years.

5. Zinc

zinc metal roof, July/Aug 2020
Alamy

As with copper, zinc is so naturally weather resistant that paint is superfluous. Often alloyed with titanium for strength and extra corrosion resistance, it’s easy to form and work with. Zinc weathers to a handsome bluish gray over time—think of the famed rooftops of Paris. Can last 80 to 100 years.

Installing a Metal Roof

Tom Silva and Kevin O’Connor get an up-close look at the standing-seam portico roof installation, July/Aug 2020
At TOH’s Arlington Arts and Crafts project, Tom Silva and Kevin O’Connor get an up-close look at the standing-seam portico roof installation. Each copper panel is laid over a slip sheet and fastened with copper nails.

You can expect an experienced metal-roofing installer to follow these time-tested practices:

Tear off the old roof

While heavily embossed metal panels can be laid over old asphalt shingles, a full tear-off of the old roof is recommended. That way, the sheathing and flashing can be inspected (and, if necessary, replaced) before the new roof goes down, reducing the chance of a leak.

Protect the sheathing

electric seamer used in installing metal roofs, July/Aug 2020

Water will get past metal joints; the best way to stop it is with a high-temperature, waterproofing underlayment stuck to the entire roof deck. This material also seals around each fastener penetrating the roof.

Allow the metal to move Slip sheets, typically rosin paper, laid between the roofing and the underlayment, allow the metal to expand and contract freely, and protect the integrity of the underlayment.

Invest in the right sealant If you see tubes of home-center silicone on the job, that’s a bad sign; it won’t last. Pros prefer polyurethane sealant formulations that are made to adhere to metal and to flex with it.

Shown: An electric seamer crimps panel edges for a tight, no-leak joint.

How to Find the Right Contractor

A quality job depends on hiring a pro who specializes in the style of metal roofing you’re after. You can start with an online product search, and then work directly with the manufacturer to find a qualified contractor in your area. Or visit the Metal Roofing Alliance’s website to connect with local pros and to view their websites for examples of their work.

Tip: Look for a roofer who will offer a warranty that covers labor in case of a leak for at least five years after installation. If a metal roof doesn’t leak in that time, there’s little chance of it leaking afterward.

Energy-Efficient Metal Roofing

metal roof from Artistic Design and Construction, July/Aug 2020
Courtesy Artistic Design and Construction

You may be surprised to learn that during peak hot-weather months, a metal roof stays 50 to 60 degrees cooler than one made from any other material.

Light-colored metal roofs naturally reflect more of the sun’s energy than darker ones, but thanks to new heat-reflective paint pigments, even dark-colored metal roofs can meet the EPA’s Energy Star criteria. In sunny places like Florida, Texas, and California, the energy savings from such roofing can be as high as 50 percent.

Elsewhere, expect air-conditioning bills to go down by 10 to 15 percent. To find roofing with a high level of performance, go to the Cool Roof Rating Council’s database. Look for products with a Solar Reflective Index (SRI) of 29 or more. The higher the SRI, the cooler a roof will stay.

Metal Roofing Cost Breakdown

metal roof price breakdown, pie chart, July/Aug 2020

Materials – 40%

This percentage can increase if high-end roofing materials are chosen, and includes unseen elements like underlayments, flashing, and sealants.

Labor – 45%

The percentage could increase if your home has complicated rooflines or a lot of dormers, or the roofing itself is difficult to install.

Tearoff disposal – 9%

Covers the cost to rent a Dumpster and dispose of the old roofing.

Jobsite extras 6% – Includes fees like renting equipment to load workers and supplies on the roof.

Myths About Metal Roofs

metal roof myth: lightning, July/Aug 2020
iStock

MYTH: They attract lightning.

REALITY: Metal is no more attractive to lightning than any other roofing material. That’s why there are no building codes that require grounding or special protection for metal roofs. Typically, lighting strikes the tallest object in the vicinity, like a chimney or a tree. But if a bolt does hit a metal roof, it won’t catch fire.

MYTH: They’re only for farmhouses.

REALITY: While metal roofs are a familiar sight in rural areas—on houses, barns, and industrial buildings—they can work on almost any architectural style. Today’s metal roofing products can mimic wood shakes, slate, clay tile, and even granule-coated asphalt, making it likely there’s a version to match your house style.

MYTH: They’re vulnerable to hail

REALITY: Hail can damage roofing of any kind, if the hailstones are big enough. In areas where hail occurs frequently, you want metal roofing with a Class 4 rating. This rating indicates that the roofing has withstood UL’s most severe impact test standard—a 2-inch diameter steel ball dropped from 20 feet—without tearing, fracturing, cracking, or splitting. If a heavy-duty hailstorm—or foot traffic—puts dents your metal roof, it may look bad, but the roofing itself isn’t compromised.

Stamped, shingle-look metal roofing is more likely to dent because there’s a small air space between the metal panel and the roof sheathing. (Standing-seam and flat-shingle roofs are in direct contact with the roof sheathing.) For those situations, a thicker-gauge metal is usually the best dent preventive, but some manufactures also offer foam inserts that support the underside of stamped, shingle roofing panels.

MYTH: They heat up a house.

REALITY: Metal roofs do get hot, but not any hotter than any other roofing material. Most formed metal roofing (the type that imitates wood, slate, or clay) comes with a built-in thermal break that insulates against heat passing to the roof deck below. And unlike asphalt, slate, or clay roofs that hold onto solar heat after the sun goes down, metal quickly releases its heat back into the atmosphere.

Metal can also reflect significant amounts of heat when the sun is up, but its reflectivity varies depending on its color and coatings.

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