Both aluminum and steel siding start as coiled metal, get roll-formed into panels, and finish with a factory-applied coating for color and weather protection. The similarities mostly end there.

Aluminum is a naturally corrosion-resistant metal — it doesn’t rust in the way steel does, because it forms a thin oxide layer on its surface that protects the metal underneath rather than flaking away and exposing fresh metal to more corrosion. It’s also considerably lighter and softer, which cuts both ways: easier and cheaper to install, but far more prone to denting from hail, thrown objects, or an errant baseball.

Steel is stronger and stiffer, which makes it meaningfully more dent-resistant than aluminum at a comparable gauge. That strength comes with a tradeoff: steel rusts if its protective coating is compromised. Nearly all residential steel siding ships with a galvanized (zinc) or Galvalume (zinc-aluminum alloy) coating specifically to prevent this, and as long as that coating stays intact, steel siding can go decades without a rust problem. The risk shows up at cut edges, deep scratches, and fastener penetrations — anywhere the coating gets broken and bare steel is exposed to moisture.

Metal siding as a category runs $4–$16 per square foot installed, and aluminum and steel sit at different points inside that range.

Aluminum’s lower material and labor cost makes it the more budget-friendly of the two in most markets. Steel commands a premium both for the material itself and for the added labor of working with a heavier, stiffer panel — but that premium buys meaningfully better impact resistance and, in most cases, a longer service life before the coating starts to show wear.

This is where the two materials diverge most in real-world performance, and it’s also where homeowner intuition is frequently backwards. Steel, not aluminum, is the more dent-resistant metal siding option. A common misconception has this reversed, likely because aluminum siding has a long reputation — earned in the 1960s and 70s installations still around today — for showing dents from hail and casual impact.

Steel’s higher tensile strength means it resists deforming under the same force that would leave a visible dent in aluminum. This matters most in regions with recurring hail events or homes near active play areas, ball fields, or anywhere impact risk is elevated. Once steel does dent, though, the damage is usually more visually obvious than an aluminum dent of the same size, because steel holds a sharper, more defined crease rather than aluminum’s softer deformation.

Aluminum’s resistance to rust is a genuine, permanent material property — it will not rust, full stop, regardless of coating condition, because rust is specifically an iron-oxide reaction and aluminum contains no iron. What aluminum can do instead is oxidize and chalk over time, a cosmetic fading rather than a structural failure.

Steel’s rust resistance is coating-dependent, not a permanent material property. Galvanized and Galvalume coatings are effective and long-lasting under normal conditions, but they are a layer sitting on top of a material that will rust if that layer is compromised. The practical risk points are:

• Cut edges made on-site during installation, where the coating doesn’t extend to the freshly exposed metal
• Deep scratches from installation, storm debris, or aggressive cleaning
• Fastener penetrations, particularly if the wrong fastener type is used or installed at the wrong angle
• Standing water contact, such as steel siding installed too close to grade or in constant contact with wet mulch or vegetation

None of these are dealbreakers — they’re installation and maintenance considerations. A well-installed steel siding job with properly sealed cut edges and correct fastening will hold its coating integrity for decades. This is one more reason installation quality matters as much as material choice; see siding installation for what a correct install actually involves.

Aluminum’s lighter weight makes it easier and faster to cut, handle, and hang, which translates directly into lower labor cost and a shorter project timeline. It’s also more forgiving to work with on tricky elevations or older homes where structural loading is a consideration.

Steel’s added weight and stiffness require more physical effort to maneuver on-site and typically call for a slightly different fastening approach to handle the material’s rigidity without kinking it. This is part of why steel installations run a premium over aluminum even before accounting for the material cost difference itself.

Coastal and high-salt-air environments generally favor aluminum. Salt air accelerates corrosion processes on ferrous metals, and while a good Galvalume coating handles this reasonably well, aluminum’s immunity to rust altogether removes the variable entirely. This is part of why aluminum has remained popular in coastal markets despite steel’s other advantages.

Hail-prone and storm-impact regions generally favor steel, for the dent-resistance reasons covered above. A hailstorm that leaves a steel roof and steel siding largely unmarked can leave visible aluminum dents across an entire elevation.

Wildfire-prone areas are a wash between the two — both aluminum and steel are noncombustible, Class A-rated materials, making either a sound choice where fire resistance is the priority. For the full picture on fire-rated material options, see the complete siding cost and material guide.

Extreme heat favors neither strongly, though steel’s higher thermal mass can make panels warmer to the touch in direct summer sun — a minor consideration unless the siding is in a location people frequently contact.

Cold, freeze-thaw climates are handled well by both, since neither material absorbs moisture the way wood-based products can, removing the freeze-thaw cracking risk entirely.

Uninsulated metal panels of either type can transmit more sound during heavy rain or hail than vinyl or fiber cement, which is a common complaint from homeowners who didn’t anticipate it. Insulated metal siding panels, or a foam backer board installed behind either material, largely resolve this. Steel’s added mass gives it a very slight edge in sound dampening over aluminum at the same panel thickness, though the difference is minor compared to what insulation backing adds.

Neither material offers meaningful R-value on its own — any insulation performance comes from a separate backer product, not the metal cladding itself.

Both materials sit at the low end of the maintenance spectrum compared to the rest of the siding category — no painting or sealing required under normal conditions, with periodic washing being the primary upkeep task for either.

The meaningful maintenance difference is inspection-based rather than task-based: steel siding benefits from an occasional check of cut edges, fastener points, and any areas prone to standing water, specifically watching for the first signs of surface rust so a touch-up coating can be applied before it spreads. Aluminum has no equivalent inspection need, since there’s no coating-failure scenario to watch for — only cosmetic chalking, which is addressable with an exterior-grade paint refresh if desired, though most homeowners simply let it happen.

Both metals are highly recyclable, and this is one of metal siding’s genuine advantages over most of the rest of the category. Aluminum in particular is one of the most recycled building materials in existence, with recycled aluminum content common in siding products and a well-established recycling infrastructure for material removed during a future replacement. Steel siding is similarly recyclable, though slightly less commonly manufactured with high recycled content than aluminum products currently are.

There’s no universal right answer — the decision comes down to which set of tradeoffs matches your specific house and location:

Choose aluminum if: you’re in a coastal or high-salt-air location, budget is a primary constraint, the home isn’t in a hail-prone region, and you want the lightest, easiest installation of the two.

Choose steel if: you’re in a hail or storm-impact-prone region, you’re willing to pay a premium for meaningfully better dent resistance, and you’re comfortable with routine inspection of cut edges and fastener points to protect the coating over time.