Metal Shingles vs Architectural Shingles: Which Is Right for an NC Home?

The difference is the material and how it is built. Architectural shingles, also called dimensional or laminated shingles, are asphalt shingles made from a fiberglass mat coated in asphalt and covered with mineral granules. Two layers are laminated together, which gives them a thicker, shadowed look compared with older flat three-tab shingles. They are nailed to the roof deck and held down by a factory seal strip that bonds to the shingle below in warm weather.

Metal shingles are panels formed from steel or aluminum with a factory paint finish, shaped to look like slate, cedar or tile. On interlocking systems such as Interlock aluminum shingles, each panel locks to the panels around it on all four sides and the fasteners are hidden under the next course.

Both go on over a solid roof deck with underlayment, both suit the steep-sloped roofs common on North Carolina homes, and both come in a range of colors. Where they part ways is weight, wind behavior, aging in heat, upkeep and price. For background on the metal side, see metal shingles and aluminum shingles.

Metal shingles that interlock generally hold up better in wind because there are no loose tabs for gusts to lift. An architectural shingle depends on its nails and its seal strip. Once a strong gust breaks that seal, the shingle can flap, crease and tear off in the next storm, which is why missing shingles are a common sight after a North Carolina tropical storm.

Asphalt shingles do carry wind classifications. The Asphalt Roofing Manufacturers Association explains that ASTM D7158 assigns Class D for basic wind speeds up to 116 mph, Class G up to 155 mph and Class H up to 194 mph, measured as 3-second gusts. The building code uses those classes to match shingles to the design wind speed where the house sits. Ask which class your shingles carry; higher-class products and enhanced nailing patterns cost more but matter near the coast.

On the metal side, Interlock aluminum shingles are rated for winds up to 120 mph when installed to manufacturer specification. Coastal North Carolina design wind speeds can be higher than that in places, and the permit office or engineer decides the requirement for a given house. See roof wind ratings explained for how to read these numbers.

Heat and humidity are harder on asphalt than on metal. Asphalt is a petroleum product, and years of strong sun dry it out. Granules loosen and wash into the gutters, the shingle mat becomes exposed, and tabs curl or crack. The U.S. Department of Energy notes that conventional roofs can reach 150°F or more on a sunny summer afternoon, which is a normal July day on a dark North Carolina roof.

Humidity brings algae. The Asphalt Roofing Manufacturers Association says algae discoloration is most widespread along the Eastern Seaboard and in the Gulf States, and it advises against pressure washing to remove it, because that strips granules. Algae-resistant shingles slow the growth but do not stop it forever.

Painted metal does not lose granules, does not dry out and gives algae a poor surface to grow on. Metal can also be ordered in cool-rated colors listed with the Cool Roof Rating Council, which reflect more of the sun's heat than a dark asphalt roof. See roof algae and mold in humid NC and metal roof colors for NC heat.

Architectural shingles cost less to install, and metal shingles usually cost less per year of service if you keep the house. Metal Roof NC's rule of thumb is that an Interlock aluminum roof typically costs about 2.5 to 3 times a traditional asphalt-shingle roof. Prices vary job to job with roof size, pitch, tear-off and other conditions, and an on-site estimate is required for an accurate price.

The longer view is the number of times you pay for a roof. An asphalt roof is replaced in cycles, and each replacement brings tear-off, disposal, new underlayment, flashing work and the disruption of a crew on the house. A metal roof installed once avoids most of those repeat costs. How the math works out depends on your roof, your plans and how long asphalt actually lasts on your house, which varies with sun exposure, ventilation and storms.

Warranties are part of the cost picture too. Compare what each warranty actually covers, who can claim it and whether labor is included. Our guides to metal vs asphalt costs over time, how long a roof lasts in NC and the metal roof cost page go further. For the material warranty on Interlock roofs, see the Guardian Lifetime Limited Material Warranty on our warranties page.

Aluminum shingles are much lighter than asphalt. Interlock aluminum panels weigh roughly 0.4 to 0.7 lb per square foot, which keeps load off older rafters and leaves more of the framing's capacity for wind and the occasional ice load.

Whether a new roof can go over an old one depends on the existing roof and the code. For Interlock roofs, cedar shingles, cedar shakes, concrete or clay tile and natural slate are always removed first. A single layer of asphalt may be roofed over only if an inspection finds it suitable and the local code allows it. The model building code does not allow re-covering a roof that is water-soaked or deteriorated, or one that already has two or more layers. New asphalt shingles over old asphalt follow the same limits.

Tearing off has advantages even where it is not required: you see the deck, replace rotted sheathing and install new underlayment. Our guide to metal over existing shingles explains the decision.

Architectural shingles are the default look in most North Carolina subdivisions, so they never raise an eyebrow with an HOA. Metal shingles in slate, cedar or tile profiles look like traditional roofing from the street rather than like a barn roof, which is why many HOAs approve them once they see samples and photos. Some covenants name approved materials or colors, so get approval in writing before you sign a contract; see HOA approval for a metal roof in NC.

For resale, a newer roof of either type helps a listing. Buyers and inspectors look at roof age, and insurers ask about it too, as covered in roof age and home insurance. A transferable metal roof warranty can be a selling point, but the value buyers place on it varies, so do not count on recovering the full difference in price at sale. Our resale value guide covers what the evidence does and does not show.

Choose metal shingles if you plan to stay in the house for many years, live where wind or salt air is a concern, or are tired of re-roofing. Choose architectural shingles if you plan to sell in the next few years, need the lowest upfront price, or your HOA will not approve metal.

Metal Roof NC installs both. As an authorized Interlock aluminum roofing dealer, it also replaces conventional asphalt-shingle roofs, so the estimate can show both options for the same house. Ask any contractor for the wind class of the shingles, the wind rating of the metal system and the full warranty documents for each. If the roof is near the end of its life now, do not let the decision drag into hurricane season; a failing roof is harder to protect once storms start. Request an estimate on our roof replacement page, and check our service areas for the Triangle, Charlotte, Triad and coast.