Steel Roof: Why Is It the Most Popular Metal Roof?

Steel roofing is the most popular choice for metal roofing, mainly due to its affordable costs. But it's also due to the material's performance, visual appeal, and versatility. What is steel roofing? And why do people choose steel over other metals like copper, zinc, or aluminum? 

What is Steel Roofing?

Steel is a type of metal composed of iron, carbon, other elements, and recycled steel. This combination of components allows the steel to be lightweight and durable enough to serve as roofing. Residential roofing can be in 24 or 26 gauge thicknesses - the higher the gauge, the thinner the steel. 

But because steel contains iron, it requires a metallic coating covering the top and bottom to make it waterproof. Without this coating, moisture and air will cause the iron to oxide - rust. 

This protective barrier is not the same as having your steel roof painted to give it a different color than its natural shiny silver surface. All steel must have a metallic coating but not all steel has to have a layer of paint. 

The whole purpose of the metallic coating is to serve as a sacrificial layer that protects the steel. So rather than letting the iron rust, the metallic coating gets exposed to the elements and oxidizes. Residential and commercial steel roofing comes in three different types.

Galvanized - 100% zinc (various thicknesses)

Zinc is more active than iron, causing it to oxidize first. When zinc does this, it forms zinc oxide - a protective layer that stops the steel (due to the iron) from becoming ferric oxide - rust. 

As a result, you can get galvanized G-90 steel (high-end) or G-60 steel (less expensive, thinner gauge). G-60 is less recommended for residential homes. The thickness refers to the zinc coating rather than the thickness of the steel - measured in gauges. 

Shake, tile, slate, and shingle style Galvanized steel typically come in 26 to 28 gauge (.018" to .014" thick), whereas 24 to 26 gauge steel is more common for standing seam panels. The weight can be between 100 and 150 pounds a square.

Galvanized steel is easy to spot due to the zinc's spangle pattern when it forms the protective coating, which is shiny and rough. There are multiple methods for creating galvanizing steel, including hot-dipping, which is the most common technique. This process creates a thick layer of zinc for better rust resistance.

It's not recommended to use galvanized steel in locations with high corrosion in the air or coastal areas. These corrosive elements can cause the steel to rust faster, reducing how long the steel lasts.

Galvalume - zinc and aluminum mixture

When you combine zinc with aluminum and silicon over an iron steel base, it forms Galvalume - the most popular choice for roofing. Over 50% of the coating consists of aluminum which gives the steel more resistance against rust while providing a matte, smooth look.

To coat steel with Galvalume, the metals are hot-dipped onto steel coils. As the coating adheres to the steel, it forms a secure bond. At this point, the metal can stay as a plain mill finish, or you can have it painted from a range of color choices. 

Galvalume weighs 100 to 150 pounds a roofing square. But the downside of this coating is that it can dent or scratch easily, making it less suitable for climates with severe weather.

Heads up!: You can also find stone-coated steel roofing - galvanized or Galvalume panels topped with stones or granules.

Weathering steel

Weathering steel, also known as Corten steel, is a low-maintenance metal with a unique appearance due to the oxidizing coating - patina. This steel develops a rusted look two to three years after installation and does not require a protective coating or paint. The proper climate is crucial to weathering steel forming a stable patina. 

Weathering steel used in wet climates has a redder hue than roofs in dry climates. But all outcomes will have an earthy, dark tone. But the results are unpredictable in terms of color. The best weather is alternating dry and wet cycles. So if you live near a coastline or in climates with heavy rainfall or humidity, you'll want to avoid Corten steel. 

Steel Roof Benefits

Steel is Recyclable.

Steel roofing is an excellent choice if you're environmentally conscious. These roofs don't break apart into pieces that can pollute the air. And once they've served their purpose as your roof protection, they are 100% recyclable. And most steel roofs may consist of recycled metals. 

Steel is Energy Efficiency.

Steel roofs provide higher energy efficiency, helping you save money on heating and cooling. While also extending the life of your unit by reducing the amount of time and power it uses to work. These roofs have high solar reflectivity, reflecting solar heat away from the ceiling rather than absorbing it. As a result, you can see energy savings up to 25%. 

Steel has Superior Durability.

Steel roofing is one of the safest choices in locations with the risk of severe weather threats like hurricanes, hail storms, and wildfires. When appropriately installed, steel can handle winds that reach 140 miles per hour. As a result, even in extreme wind, steel won't break, crack, or corrode. Steel also won't shrink or erode due to weather changes and thermal expansion.

Savings alert!: You can get insurance premium discounts for installing a steel roof in some states due to its superior performance over less durable materials like asphalt shingles.

Steel Comes in Multiple Options.

When it comes to steel roofing, you have a few different choices on styles. If you want the look of traditional metal roofing, you'll want to go with a standing seam. But if you're going to keep the look of traditional roofing, you can also find metal shingles or slate. 

You can also get steel in various colors, using high-quality paints like Kynar 500, including colors that meet Energy Star and LEED cool roofing compliance. 

Steel has an Extended lifespan.

All metal roofs have a longer lifespan than non-metal materials. For example, a steel metal roof can last two to three times longer, with an expected life cycle of 15 to 30 years. However, compared to stronger metals like copper or zinc, which have a longevity of 80 years or more, steel has a shorter life expectancy.

Steel Roofs Have High ROI.

While installing a metal roof is more expensive than non-metal roofs, you can recoup the costs if you sell your home within the first five to ten years after installing your metal roof. You can expect to recoup an average ROI (return on investment) of 85.9% during reselling.

Steel Roof Disadvantages

Steel roofs are vulnerable to coastal climates.

Although steel has an excellent performance in climates with severe wind threats, it can be susceptible to abrasions from saltwater over time. In addition, the coating that protects the steel can separate from the substrate, leading to rust. 

Galvalume is three times better at blocking rust than galvanized steel, making it a better material for saltwater conditions and hot or humid climates. Conversely, galvanized steel is best for dry climates free of significant air pollution or water pooling.

Steel roofs have edge creep.

The majority of steel roofing will have edge creep along the cut edges. For Galvalume, which is self-healing, this creeping will stop rather than spreading rust through the rest of the panel. However, galvanized steel does not self-heal, so the edge creep worsens over time, leading rust to spread over the panels.

Steel roofs don't have warranties.

When you choose a Galvalume steel roof, you typically get a warranty, while galvanized steel does not come warrantied. The reason for this is that Galvalume has a higher reputation for longevity and durability. On the other hand, galvanized steel can be more unreliable and have poorer performance, especially if it starts to rust. 

Steel roofs are difficult to repair.

If you choose standing seam roof panels for your design, be aware that this option can pose challenges if your roof needs repairs. Metal shingles are easier to make repair work.

Steel roofs can experience tension bend.

Galvalume is more vulnerable to tension bend straining, which is when the metallic coating is so thin in the folds or bends of the metal that microscopic cracks form. For this reason, Galvalume is best for standing seam panels on simple roofs that don't require much bending of the steel.

Steel Roof Prices

Steel is a moderate-priced option for metal roofing, cheaper than more luxury metals like copper and zinc but more affordable than aluminum. 

You can expect costs of around $4 a square foot ($400 a roofing square - 100 square feet). If you want to use steel shingles, the price is slightly lower at $3.50 to $4.50 a square foot or $350 to $450 a roofing square. 

Factors that can affect the final cost of your installation include your roof's size, pitch, and slope. Also, if your home is more than one story, you'll pay more for installation. 

Heads up!: If you want to estimate the costs of your roof install, try using a handy calculator like this one.

Steel Roof Repairs

Over time and exposure to the elements, the metallic coating that protects steel will deteriorate. To keep your roof protected, it is necessary to recoat the steel with a polymer coating - Kynar is a common choice. 

If your roof starts to look scuffed up, or you're just tired of the same look, you can repaint steel without damaging the surface.

Steel Roof Upkeep

Steel roofs have low maintenance, rarely requiring you to do much to keep them in optimal condition. If your roof gets dirty, you can clean it with a mild detergent and water from a hose or pressure washer. But it would be best if you did not use abrasive tools (steel wool or wire brushes), as these can cause the roof to scratch.

Unlike zinc, which has self-healing properties, steel will not repair itself if it gets scratched. However, you can wipe down scratched areas with mineral spirits and then touch up the area with a paintbrush.

Steel Roof vs. Other Metals

So, how does a steel roof compare to other metals? First, steel is one of the cheapest metals, less expensive than premium metals like zinc, copper, and aluminum. 

In terms of weight, steel is one of the heavier metals, weighing 200 pounds a roofing square (100 square feet), compared to aluminum's 70 to 100 pounds a square. Copper and zinc weigh 100 to 125 pounds a square. 

Steel roofs typically have a painted surface to give them better curb appeal on your home. Metals like copper and zinc have a patina process that changes the color of the metal over time. While zinc may have a painted surface, copper is typically left in its natural state. Aluminum does not have a patina process and can be left in its shiny natural state or painted. 

In terms of life expectancy, steel has the shortest lifespan of 30 to 50 years, similar to aluminum, which also lasts 50 years. However, both copper and zinc are called lifetime roofs due to their propensity to last 80 to 100 years or more.

Final Verdict

Steel roofs are the most popular choice for homeowners due to their low costs, extended lifespan, and appealing look. Whether you want a roof in a unique color or the shiny surface typical for metal roofs, steel can be the metal for your home. 

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