When it comes to roofing, corrugated metal has become a popular choice due to its durability, cost-effectiveness, and versatility. There are myriad types of metal panels, ranging from copper to steel to galvanized, available in patterns and colors galore. But with so many different types of metal roofing available, choosing the right one for your project can be confusing or even overwhelming. In this blog, we’ll compare some of the lesser-known yet oft-used corrugated metal roofing materials: aluminum, stainless, and ASTM A606 Weathering Steel.
We’ll look at the strengths, weaknesses, and characteristics of these materials to help you make an informed decision about which material is best suited to your application as well as valuable insights about design and installation.
Metal is known as a strong, durable, corrosion-resistant building material, and parts carefully selected to meet the needs of any project result in a stronger complete structure. Different gauges (or thicknesses) of sheet metal are formed into a variety of shapes or “profiles” for use as the outer covering of a roof. Depending on your application and final material choice, it can also provide other advantages:
- Safety: Metal roofs won’t spark and ignite during lightning strikes or wildfires, protecting structures from roof collapse due to fire damage.
- Energy savings: Metal roofs reflect UV and infrared rays that contribute to roof surface radiant heat. This can result in up to a 25% reduction in cooling costs.
- A green choice: Not only are metal roofs comprised of 25-95% recycled materials, but they are also completely recyclable when their lifespan as a roof comes to an end. (To add context, most waste from a typical shingle removal adds to the building-related waste stream which amounts to nearly 100 million tons of waste in the United States alone.
Let’s talk about the “corrugated” part of metal roofing panels. Their wavy patterns aren’t simply for looks; the corrugated design adds strength to the panels by increasing their rigidity and their ability to distribute the weight of the panels more evenly over the supporting structure. Plus, the sheets usually take less time to install than asphalt shingle or wood shakes.
Now we’ll explore some of the metal options available to architects, engineers, contractors, and homeowners besides standard or galvanized steel: aluminum, stainless steel, and ASTM A606 Weathering Steel.
Using Aluminum Roof Panels
Corrugated aluminum roofing panels are a popular roofing material due to their durability, light weight, and ease of installation. Made from aluminum sheets that have been formed into a series of alternating ridges and valleys (which increase the strength and stability of the panel) corrugated aluminum panels are a popular choice for both commercial and residential applications.
- Versatility: They’re available in a range of sizes and thicknesses to suit different roofing needs and coated to enhance their longevity. Aluminum panels are also relatively easy to install and maintain, making them a cost-effective choice for those looking for an efficient and long-lasting roofing solution.
- Adding to their versatility and appeal, aluminum panels come in a variety of colors and finishes to match different design aesthetics and can be customized to fit different roof shapes and sizes.
- Strength: Corrugated aluminum roofing panels have a very high strength to weight ratio. Since aluminum is lightweight compared to other metals like copper or steel, it’s an ideal choice for roofing applications where weight is a concern. In other words, aluminum can supply the same level of strength as steel while weighing significantly less. Aluminum’s strength makes it a suitable choice for roofing panels used over broad spans and in areas with high winds or heavy snow loads.
- Durability: Corrosion resistance adds to aluminum’s durability. It’s an ideal choice for use in coastal or humid environments where other metals may corrode or rust over time.
- Energy efficiency: Aluminum is a highly reflective material, which means it can help to reduce the amount of heat that your roof absorbs. This can lead to lower overall energy costs since your HVAC system won’t have to work as hard to keep your home or business cool. Of further note on the green features of aluminum, it is also a highly recyclable material, which means it can be reused or repurposed at the end of its life to help reduce waste and environmental impact as well as yield cost savings if you decide to recycle an old aluminum roof.
- Cost Effectiveness: Even though the initial cost may be higher than some other roofing materials, aluminum panels can be a cost-effective choice for many home and business owners. From the start, the lightweight material is less expensive to transport than its heavier counterparts. The lighter panels are also easier to handle, which may reduce installation costs and enable roofers to complete the job in less time. Since the panels are resistant to rust corrosion and other types of damage, you won’t need to spend money on cleaning or repairs over the lifetime of the roof.
Stainless Steel Panels
Stainless steel is another popular choice for roof panels, as it’s easy to work with and offers design versatility. Typically, roof panels are available in a standard mill finish (2-B), which has a dull appearance. Most manufacturers offer the standard 2-B mill finish, (which has a dull appearance), a brushed finish (for more decorative looks, like stainless appliances) or a shiny, mirrored finish. Different gauges of steel are used for different circumstances, taking necessary calculations (e.g., loads, spans, etc.) into account. Stainless can be customized for your application, and both stock and custom panels afford users several key benefits:
- Corrosion resistance: Whichever stainless you choose, nothing can match this material’s corrosion resistance to the elements. A stainless material does not have an equal for weather durability and will retain the same look as the day it was installed. This is due to chromium in the metal. It helps form a protective oxide layer on the surface of the steel, preventing rust and other forms of corrosion from penetrating the material. Since the primary cause of roof failure is corrosion, stainless steel offers a huge advantage over most other metals in this respect.
- Strength: Stainless is not as strong as some of the other types of metal roofing due to a lower strength to weight ratio, but is still suitable for many roofing projects, particularly where corrosion from the elements is of concern. Stainless also offers a high degree of impact resistance and can tolerate heavy loads without cracking or otherwise becoming deformed. This makes it ideal for use in areas prone to hail or other severe weather.
- Fire resistance: Stainless steel has a high melting point and is not combustible, which means it is incredibly resistant to fire. This can be particularly beneficial in areas where wildfires are likely or where fire codes require non-combustible roofing material.
ASTM A606 Weathering Steel for Roofs
If you’re looking for roofing material with high strength, unique appearance, and minimal maintenance requirements, consider using weathering steel. Over time, this natural metal develops an orange-brown oxidizing finish that helps keep it resistant to corrosive elements. Weathering steel has been used in construction for years, but it’s recently become more commonly used as roofing and siding, especially since its appearance lends itself to the popular farmhouse and industrial aesthetics.
Weathering steel was developed as an alloy containing small amounts of copper, phosphorus, manganese, chromium, nickel, and silicon. The presence of these materials allows for chemical reactions, so the steel sheets form a layer of rust when exposed to elements.
This material is also incredibly strong, compared to similar roofing materials. With a tensile strength of 68 to 78 KSI and a tensile yield of 50 KSI, weathering steel can withstand stronger forces before buckling or breaking. (Regular galvanized steel sheets are 45 to 64 KSI.) Conjoined joints will fuse via weathering steel’s surface rust and this fusing quality adds to the strength of structures. Within a year or two, it will become a solid piece from end to end, making it extremely stiff and durable.
- Durability & Longevity: Generally, builders and engineers work to avoid rust, so it seems counterintuitive to aim for it to happen. But with ASTM A606 Weathering Steel, a rusted patina is the desired result. Not only does it give the metal a unique appearance when exposed to moisture and oxygen, the newly formed coating becomes a protective barrier that lengthens the lifecycle of a weathering steel structure. (The layer usually develops in about six months, depending on the environment.) Once the coating is depleted, the steel ionizes, which means it doesn’t continue to rust through. All of this means a longer lifespan – anywhere from 40 to 60 years – for your roof. This superior corrosion resistance makes Weathering Steel an optimal choice for roofing on structures that will be exposed to harsh weather and environmental conditions.
- Affordability: With weathering steel, there’s no need to paint since the protective layer provides aesthetic value and precludes the need for shielding it from the elements. This saves both on lead time and manufacturing expense, as well as long-term maintenance costs. Maintenance is minimal with weathering steel, largely because if it’s scraped, the newly exposed steel will oxidize rapidly and will blend in with the rest of the surface.
- Versatility: Available in sheets or plates ranging from 2 to 40 mm thick, weathering steel is as versatile as it is durable. For roofing, the steel is usually cold-rolled and is available in many profiles for use as roofing (and siding) panels. A variety of available shapes, sizes and custom fabrication all make this a versatile material from a design and engineering perspective. (In fact, sculptors often choose weathering steel for projects as it can be used to create unique shapes with ease.)
The natural patina will vary depending on the amount of humidity, warmth, and airborne contaminants but it’s generally viewed as aesthetically pleasing; the rich color of the oxidized metal provides contrast to greenery or, in desert or mountain areas, blends in with the landscape. Both make it a popular design choice.
The Cons of Metal Roofing
As with any building material, there are also potential disadvantages to consider before making the final choices for your project. Some of the concerns about metal roofs include:
- Higher Initial Investment: Metal roofs can cost more than other materials, often two to three times more. However, the life of a metal roof is far longer than other materials, so it can still be a wise choice. This is particularly true if you intend to be in your home long enough to enjoy the return (low to no maintenance costs, energy savings, etc.) on your investment.
- Noise: One of the chief complaints about metal roofs is noise; often, they are not as quiet as roofs made of other materials, particularly during heavy rains or hailstorms. Noise can be mitigated with solid decking and ensuring there’s adequate attic insulation.
- Color Match Concerns: If a section of painted metal roof needs to be repaired or a new section is added (due to a remodel/addition to the original structure) years after installation, it may be difficult to match the color exactly due to weathering and availability of paints and finishes.
- Installation Woes: Proper installation is key with metal roof panels. Poor installation or repair can cause a marked decrease in the performance of your roof. For example, if water accumulates anywhere on the roof due to installation errors, it can cause serious damage to the roof and structure. It’s also crucial to use appropriate fasteners to assemble your roof. Metal roof panels are designed to expand and contract with temperature fluctuations. But fasteners, whether they are exposed or concealed, have varying lifespans. Be sure your fasteners, especially neoprene washers and screws, don’t degrade or become dislodged during your roof’s lifetime.
Be sure your metal roofing is from a reputable manufacturer and has been tested and labeled, preferably by an organization (e.g., Underwriters Laboratory, Intertek, Factory Manual Approvals, etc.) with stringent requirements for wind, fire, and impact ratings.
Proper installation is paramount to the performance of your metal roof; ensure your installers are knowledgeable, experienced, and reputable. Installation protocols can also vary by geographic region and climate, so consult the manufacturers’ recommendations and the local building code.
Whatever type of metal roofing material you choose, you can be assured that, when properly installed, it will provide durable, strong, attractive, and high-performing cover for your structure for decades. Metal roofing is a long-lasting choice.
A leading manufacturer of roll-formed and corrugated metal products for the construction industry, Corrugated Metals offers the widest range of materials, finishes, and in-house production capabilities for metal roofing and beyond. We have the expertise to help you select the best options for your projects and supply high-quality material for design and construction of your commercial, architectural, and industrial construction needs. Have more questions? Get in touch with us today!