Metal roofing has become a leading material commonly used in the roofing industry, widely favored by homeowners and contractors. Its popularity comes as no surprise, given its durability and the ability to protect homes in any climate, often lasting the lifetime of the homeowner, and sometimes, even their children! Metal roofs offer great curb appeal, amazing warranties, require minimal maintenance, and provide a vast variety of colors/styles. Among metal roofing options, the two most popular types are standing-seam (concealed fastener systems) and exposed fastener system metal roofs. We will explore the different types of metal roofs, their advantages, disadvantages, and everything you need to know about metal roofing to make the best decision for your next roof replacement.
5 Most Common Materials for a Metal Roof
Pros of Galvalume
- Most commonly available amongst metal roofing manufacturers
- Most affordable metal roofing material
- Many types, styles, and colors
Cons of Galvalume
- Corrodes faster than other metal roofing materials
- Manufacturers will not warranty within specific distances of salt water
- Not recommended for coastal climates
Aluminum: is the second most popular material for roofing on the market, with a lifespan of 30 to 50 years. Its widespread popularity stems from its exceptional anti-corrosive properties, making it a durable and reliable choice. While aluminum may come with a higher price tag compared to some other materials, it offers significant advantages. It requires less maintenance than Galvalume and provides superior protection against the elements. Known for its impressive strength-to-weight ratio, aluminum is one of the lightest materials available for metal roofing, yet it remains incredibly strong. Aluminum is particularly favored in coastal climates, where its resistance to salt-filled air ensures long-lasting performance and protection. Homeowners in these regions often choose aluminum for its resilience and minimal upkeep requirements. In summary, aluminum roofing stands out for its durability, low maintenance needs, and superior protection, making it an excellent choice for homeowners seeking a long-term roofing solution.
Pros of Aluminum
- Stronger material
- Anti-corrosive with specific coatings such as zinc-alloy coating
- Low maintenance, especially in coastal areas
- Most affordable metal roof option for coastal ares
Cons of Aluminum
- More expensive than Galvalume
- Has less color options
- Prone to denting if you don’t choose a thicker gauge
- Expansion is greater with aluminum in comparison to galvalume
Stainless Steel: is an iron alloy regarded as a high-end option for metal roofing. The primary distinction between stainless steel and regular steel is the addition of chromium. This element creates a protective seal within the metal, preventing oxygen from causing rust and extending the lifespan of stainless steel to 50 to 70 years or more. Stainless steel is among the toughest materials available for roofing and offers remarkable resistance to corrosion. Despite being a premium choice, it is more affordable compared to other high-end options, providing superior protection and longevity without breaking the bank. This makes stainless steel a great investment for homeowners seeking durability and long-term performance.
Pros of Stainless Steel
- Longevity
- Increase property value
- Great in any climate
- Increased curb appeal
- Low maintenance
- Most affordable of luxury options
Cons of Stainless Steel
- More expensive than aluminum
- Color options are limited
- Expands and contracts more than their metals
Copper: is easily recognizable and is considered a luxury material in the roofing world. Its distinctive color and unmistakable appearance make copper a top choice for homeowners seeking high curb appeal. The aesthetic appeal of copper roofs is unparalleled, offering a timeless elegance that enhances the overall look of any home. One of copper’s most notable features is its impressive lifespan. With proper maintenance, a copper roof can last between 50 to 80 years or even longer. This longevity makes it a valuable investment for homeowners who want a durable and long-lasting roofing solution. Copper is also highly resistant to corrosion. Over time, it develops a natural protective layer known as patina. This patina process transforms the copper into a beautiful greenish-blue color, adding to its charm and uniqueness. The development of patina not only enhances the roof’s appearance but also provides an extra layer of protection against environmental elements.In summary, copper roofing stands out for its luxurious appearance, exceptional durability, and natural protective qualities. It’s an ideal choice for those who desire a roof that offers both beauty and long-term performance.
Pros of Copper
- Highly anti-corrosive
- Longevity
- Increases value of property
- Excellent Curb appeal even when aged
- Perfect for any climate
Cons of Copper
- More expensive than most materials
- Softer metal so easier to dent
- Limited options in color
Zinc: is another top-tier option in the world of metal roofing, renowned for its aesthetic appeal and exceptional durability. With a lifespan ranging from 80 to 100 years, zinc offers long-term value and reliability. One of the standout features of zinc is its ability to develop a patina, similar to copper. This natural process not only enhances its appearance over time but also creates a self-healing effect, ensuring the metal remains resilient. The patina acts as a protective layer, making zinc highly resistant to corrosion.Thanks to its anti-corrosive properties, zinc thrives in various environments, including coastal areas. Its durability and low maintenance requirements make it an attractive choice for homeowners seeking a reliable roofing solution.In addition to its practical benefits, zinc roofing can significantly increase your property value, making it a wise investment for the future.
Pros of Zinc
- Luxury look
- Perfect for any climate
- Longevity
- Increases property value
- Has self healing properties
- Highly anti-corrosive
Cons of Zinc
- More expensive than most materials
- Limited in color options
- Softer metal than is easier to dent
- Expands and contracts more than most materials
What is a Standing Seam Metal Roof?
A standing seam metal roof is distinguished by its raised seams that run vertically along the panels, typically spaced 12 to 24 inches apart. These seams interlock to create a continuous protective barrier against the elements. One of the key features of standing seam roofs is their hidden fastening method, where the metal panels are securely attached to the substrates without visible fasteners. This unique design not only enhances the roof’s appearance but also ensures superior weather resistance and longevity.
Standing Seam Metal Roof – By Sentrigard
Types of Standing Seam Metal Roofs
Snap-Lock Systems: Snap-lock systems are designed with interlocking edges that snap together, simplifying the installation process and reducing time. These systems are particularly well-suited for residential applications, offering ease of use and reliable performance. Despite their convenience, snap-lock systems may not provide the same level of strength as mechanically seamed systems in extreme weather conditions.
Mechanical Seam Systems: Mechanical seam systems involve panels that are mechanically seamed together using a special seamer tool. These profiles have panel edges with vertical legs that line up, so the male leg goes down, then the clip goes over that leg and is fastened down. The female leg of the panel goes over the clip to conceal it. These components are seamed together by a single or double lock:
- A single lock is one fold of the seam (or 90 degrees).
- A double lock is two folds of the seam (or 180 degrees). This method creates a robust and weather-tight seal, making it ideal for areas prone to harsh weather. Although installation is more labor-intensive, the added durability makes it worth the effort.
Western Seam Nail Strip (Flange): Western seam nail systems, also known as nail flange or fastener flange systems, are installed with nail strips attached to the male side of the panel. The female side of the next panel then covers the male lip, concealing the nail strip. These roofing systems offer the fastest installation process and are the most cost-effective option for standing seam roofs. However, they are also the least durable and prone to incorrect installation if not done properly.
Advantages of Standing Seam Metal Roofs
Standing seam metal roofs offer several advantages, making them a preferred choice for many homeowners:
- Longevity: These roofs are known for their long lifespan, often lasting 40 to 70 years with minimal maintenance.
- Weather Resistance: Hidden fasteners significantly reduce the likelihood of leaks, while the interlocking methods create a strong, watertight seal. This roof system is specifically designed to resist water, ensuring enhanced durability and protection.
- Energy Efficiency: The reflective properties of metal roofs help reduce cooling costs by reflecting solar heat, making them energy-efficient.
- Minimal Maintenance: All that is required is yearly maintenance of cleaning and removing debris. If you do see anything abnormal like rust or other evidence of leaks forming, call a roof inspector over asap. It’s always better to catch roofing issues early.
- Aesthetic Appeal: Available in various colors and finishes, these roofs can enhance the visual appeal of any home.
- Durability: Standing seam roofs typically are awarded Class 4 impact rating which is the best rating a roof can achieve.
Benefits/Advantages of Mechanical Seam Panel Profiles
- Versatile Locking Options: You get the benefit of choosing between both single lock and double lock systems without sacrificing your roof’s aesthetic. Single lock systems (one fold or 90 degrees) perform well in milder environments, require less labor, and make replacing damaged panels easier. Double lock systems (two folds or 180 degrees) are suitable for low-slope applications needing extra weathertightness and are more effective in cold weather areas with freezing and thawing, although they are more labor-intensive to replace.
- Low and Steep-Slope Roofing Applications: Mechanically seamed profiles are effective on both steep-slope and low-slope roof surfaces. While it’s generally not recommended to go below a 2:12 roof slope for most projects, there are specific low-slope scenarios where a mechanically seamed profile can be properly installed. For example, the Sentrigard ML200 series panel can be installed on pitches as low as ½:12 roof slope. This flexibility provides homeowners with more options and design choices for their home’s appearance.
- Engineering & Higher Performance: Mechanically fastened roofs are highly engineered to withstand extreme weather, making them a high-performance option. The Sentrigard ML200 series panel, for example, has been tested for uplifts, wind-driven rain, fire resistance, and hail impact. It has received approvals from the Florida Building Code and Miami-Dade Building Code Compliance, positioning it as a top contender for high-performance roofs.
What is an Exposed Fastener Metal Roof?
An exposed fastener metal roof features panels secured to the roof deck with visible fasteners, such as screws or bolts, installed through the panel and into the substrate. The visible fasteners add to the aesthetic that many homeowners prefer when choosing an exposed fastener roof. These roofs can be installed over open frames, providing homeowners with more options and excellent protection against the elements.
Example of an exposed fastener roof by Perfect Solutions
What Are The Kinds of Exposed Fastener Roofing Systems?
Here are some of the most common forms of exposed fastened metal roofs.
- Ribbed or Corrugated Panel Systems
Corrugated panels, often referred to as “ribbed” panels, are one of the most common types of exposed fastener roofing systems. These panels have raised ribs that run along the length of the roof, which are fastened directly to the roof deck. Ribbed panels are typically used in both residential and agricultural applications due to their affordability and ease of installation. The interlocking design helps to shed water efficiently, but regular maintenance is needed to ensure the fasteners remain tight and prevent leaks.
- Western Rib Panels
Western rib panels are similar to ribbed panels but have deeper ribs, making them ideal for low-slope roofs and providing greater strength and wind resistance. These panels are often used in commercial and industrial buildings and are capable of handling heavy snow loads and wind uplift. Although exposed fasteners are part of the design, the deep profile allows for better drainage and overall weather performance.
- 5V Crimp Metal Roofing
This metal roof is a type of exposed fastener metal roofing system that features five V-shaped ribs that are spaced 12 inches apart across the panel. The “5V” signifies the number of these V-shaped ribs on each panel, making it a common choice for both residential and commercial buildings due to its durability and classic look. A 5V panel roof is typically coated with a layer of Galvalume, which is a zinc-aluminum alloy coating applied to a steel core, providing protection against corrosion and weathering; essentially, it is a pre-coated metal panel designed for roofing applications.
- R-Panel
R-Panel is a multi-use wall and roof panel used primarily in pre-engineered metal building applications. R-Panel is also a popular choice for residential metal roofing, especially in the Southwest. An optional purlin bearing leg (PBR) rests on purlins and provides support for fastening the panel lap. Fade and Chalk resistant Kynar 500 (PVDF) coatings are a McElroy Metal standard for R-Panel and provide building owners with a long-term, high performing panel that retains its original color and beauty year after year. (Definition of R-Panel given by McElroy Metal)
Exposed fastener panels are identified by 5 main criteria:
- Rib Height
- Center to Center Rib Spacing
- Panel Width
- Cover Width after lapping
- Minimum Slope
Advantages of Exposed Fastener Metal Roofs
Exposed fastener metal roofs provide several key advantages, making them a cost-effective and reliable roofing solution for various applications:
- Variety: Exposed fastener roofs offer an extensive selection of options in terms of strength, style, color, and architectural design. With a history spanning over 100 years, the variety available is virtually limitless. This long-standing popularity ensures that you can find the perfect match for your needs and aesthetic preferences, making exposed fastener roofs a versatile and customizable choice for any project.
- Cost and Installation: Installation for exposed fastener roof systems is less intricate so that means its faster to install and less things can go wrong. It is also a more cost effective option because you need less materials and there are more contractors available to install exposed fastener roofs.
- Durability: Metal ranks high in durability, being one of if not the strongest material that is available for roofs. Exposed fasteners roofs have the highest impact rating (class 4) and high wind resistance.
- Low Maintenance: Though not a low maintenance as standing seam exposed fastener roofs are still a great low maintenance option. Annual fastener checks, rust cleaning and eat checks will check your roof in good condition.
Factors to Consider When Choosing Metal Roofs
When selecting a standing seam metal roof, consider the following factors:
Material Options
The 5 most common materials are galvalume, aluminum, stainless steel, zinc and copper. Each material brings specific qualities to the table. It’s essential to research and determine which attributes—such as durability, cost, maintenance, or aesthetic appeal—are most important to you and your roofing project.
Cost Considerations
Standing seam roofs may come with a higher upfront cost compared to other metal roofing systems, but they offer exceptional reliability. Their design features, such as hidden fasteners, snap lock mechanisms, and mechanical seams, significantly reduce the likelihood of costly repairs. This investment ensures long-term durability and minimal maintenance, making standing seam roofs a smart choice for homeowners seeking a cost effective roofing solution.
Climate and Environmental Impact
When selecting a roofing system, it’s crucial to consider the climate to ensure optimal protection for your home.
- Harsh Climates: For regions with frequent storms, severe weather, freezing temperatures, or scorching summers, a mechanical seam roof system is highly recommended. These systems offer exceptional strength and durability, capable of withstanding extreme conditions.
- Moderate Climates: In areas with milder, more moderate climates, a snap lock system or exposed fastener systems are ideal choices. These systems provide sufficient protection and are well-suited to environments that do not experience extreme weather variations.
What are the Installation Requirements for Metal Roofs?
When it comes to installing metal roofs, it’s essential to hire a qualified contractor to ensure proper installation and optimal performance. Metal roofs are known for their complexity and high installation costs, so expertise is crucial.
- Certified Contractors: Many contractors gain their skills through on-the-job experience, but it’s vital to choose one certified by the manufacturer. Certification ensures that the contractor has received specific training and adheres to the best practices for installing the product.
- Importance of Certification: Hiring a certified contractor guarantees that they understand the intricacies of standing seam roofs and can handle the challenges they present. You also want to look for contractors who offer a workmanship warranty, meaning any installation issues fall under the contractor’s responsibility, offering you peace of mind.
What is a Good Metal Warranty?
When choosing roofing products, it’s crucial to select options that come with comprehensive warranties. These warranties should cover both materials and installation to ensure that your investment is protected from potential issues.
- Material Coverage: A warranty that covers materials guarantees that any defects in the roofing product itself will be addressed by the manufacturer. This includes issues like premature wear, manufacturing defects, and material failures.
- Transferability: Some warranties can be transferred to new homeowners if you decide to sell your property. This adds value to your home and can be a selling point for potential buyers.
- Warranty Duration: Check the length of the warranty to understand how long you are protected. Some warranties may last for decades, providing long-term security for your investment.
- Exclusions and Limitations: Read the fine print to understand what is not covered by the warranty. Knowing these details will help you make informed decisions and avoid unexpected costs.
By choosing roofing products with comprehensive warranties, you are safeguarding your investment, ensuring long-term durability, and adding value to your home. This proactive approach will help you avoid costly repairs and maintain the integrity of your roof for years to come.
What Underlayment should you use for a Metal roof?
The underlayment you choose will significantly impact your roof’s performance. Underlayment is a thin material laid between the cladding (metal) and the decking (wooden board) of the roof. It serves as the primary waterproof barrier, protecting your home from leaks. Synthetic underlayment is an excellent choice for metal roofs due to its strength and durability. Unlike traditional materials, synthetic underlayment doesn’t break down over time, providing long-lasting protection against moisture. This ensures that your roof remains leak-free and your home stays dry. In addition to its durability, synthetic underlayment is available in UV reflective options and high temperature options. These reflect heat away from your roof, helping to prevent paint from fading and reducing your energy bills by keeping your home cooler.
- Fire Resistance
Increased fire protection: Many high-temperature underlayments are made from fire-resistant materials, offering crucial protection, especially in wildfire-prone areas. Some underlayment products also feature fire-retardant properties, providing an additional layer of safety to your roof structure.
Investing in high-quality underlayment, particularly synthetic varieties with UV reflective and fire-resistant features, is essential for the long-term performance, safety, and efficiency of your metal roof.
The Biggest Issue with Metal Roofs is “Oil-Canning” - So, What is Oil-Canning?
Oil Canning can be defined as visible waviness in the flat areas of metal roofing and metal wall panels. In technical terms, oil canning is referred to as elastic buckling (more commonly known as “stress wrinkling”). It can occur in any type of metal panels: steel, aluminum, zinc, or copper. For purposes here, all four terms shall be considered synonymous: Waviness, elastic buckling, stress wrinkling and oil canning. The degree of waviness can be difficult to measure, but may be apparent, especially under specific lighting conditions. Generally the period and amplitude of the wave will become more pronounced as the panel width increases (flat portion of the panel) and/or the panel thickness decreases. Reflected light may make the oil canning more prominent at certain times of day. Conditions such as the time of year, the viewing angle, and the angle at which sunlight strikes the panel may also have an impact on the ability to discern oil canning. The eye perceives the reflection of light, and when the reflective surface is irregular the reflected light is also irregular making it more perceptible. If oil canning is present, it is usually apparent at the time of construction.
What Causes Oil Canning?
According to Sentrigard’s technical bulletin, “Does your Product Meet Code Requirements,” “oil canning is caused by differential stresses within the metal itself. As the metal tries to relieve these stresses in panels with high width to thickness ratios, material buckles out of plane producing the characteristic waviness of oil canning. The stresses may be introduced at a number of stages in panel manufacturing.”
(Please read the following from the technical bulletin):
“1. Metal Coil Production
All fabricated metal roof and wall products begin in a “coil” form. Coil is produced in a rolling process under pressure to create very thin strips which are then “coiled” for ease in handling. Stresses induced during coil production may contribute to oil canning.
Examples of these types of stresses are:
Full Center – Coil is longer in the middle of the strip which creates ripples or buckles near the mid-coil area.
Wavy Edge – Coil is longer along the edge of the strip.
Camber – Coil deviation of a side edge from a straight line.
These conditions exist to some extent in all light gauge flat rolled metal coil and tend to become more exaggerated as the material tensile strength increases. Thinner material and dimensionally wider coil is also more prone to oil canning than thicker, narrower coll.
- Coil Processing and Panel Fabrication
Slitting – Generally several narrower coils are cut by slitting from a single (wider) master coil. The economies of producing wider coils makes this secondary process a common practice. Slitting of a master coil can release and redistribute residual forces. This redistribution of stresses can increase the occurrence of oil canning within the final
Forming – Stresses are introduced during forming of either roof or wall panels. Architectural panel profiles typically require more forming along the edges than in the middle of the sheet. This often necessitates more forming and bending along one side than the other and the stresses produced are not symmetrical within the sheet. Formed panel profiles require “working” (bending) of the sheet.
Bending occurs along the edges and there is a tendency to “trap” uneven stresses within the center portion of the finished profile, producing oil canning. In contrast to flat, architectural profiles, corrugated ribbed profiles are most often roll formed from the center and moving outward, thereby “pushing” the differential stresses to the edges of the sheet.
Forming sheet metal inherently introduces stresses to the material. Equipment tooling, setup and operation can minimize these stresses. Proper feed rates, tooling maintenance, proper tooling design, and proper adjustment of the equipment will minimize the differential stresses that cause oil canning.
- Support Systems and Substrate Suitability
Misalignment of the Support System – If the structural supports or perimeter framing system of a roof or wall panel system are not flat, “non-planar” or contoured, additional stresses can be induced into the sheet as the panels are forced to conform to this uneven surface.
Movement of the Primary Structure – If the primary structure moves due to differential deflection, racking, drift, settlement or other causes oil canning can occur as the panels are forced to conform to this movement. This oil canning is sometimes temporary as the support system continues to move, but could be permanent depending on the root cause of the movement.
Camber – Commercial support structural elements such as roof rafters and trusses are often designed with an intentional bow or camber, anticipating deflection under load. If the rafter, truss, or joist is fabricated with camber (crowning at mid-span) it produces a contoured substrate that can induce oil canning of the finished surface at installation or after a load is imposed.
The above roof is taken while the sun is at an angle that doesn’t show any oil canning.
The above roof is taken while the sun is at an angle that does show oil canning, pictures are of the same roof, just hours apart.
- Panel Installation
Over-Engagement of Panels (Roof Panels) – Roof panels are designed to a specific coverage dimension and accommodate transverse thermal expansion by flexing the rib and seam areas of side joints. When panels are not installed true to the intended coverage dimensions, these stress relief features can be minimized or eliminated altogether.
In the extreme case, the over engagement process itself can generate oil canning within the flat areas of the panel.
Improper Installation (Wall Panels) – Wall panels are generally designed to a specific coverage dimension and to accommodate thermal expansion.
Panels often do this by expanding/contracting at the joints located between the panels. Panels can be designed with slotted connections or extrusions that slide across each other to accommodate this movement. When panel joints are not designed or located properly, stress relief cannot take place and oil canning can be the result.
Over Driving of Fasteners – This installation error can create stresses in the panel and can cause visible oil canning along fastener lines.
Thermal Expansion – Due to the profile of panels, longitudinal expansion is generally the primary concern. Any expansion across the width of the panel is generally taken up at the raised portion of each profile. The surface temperature of exposed panels cycles throughout the year and even fluctuates daily. The range and cycle depend on many variables (e.g., project location and building orientation, cloud cover, surface finish or color, solar absorption characteristics, etc.). As the panel surface temperature fluctuates,panels expand or contract.
Surface temperature may be more than 100 degrees higher than ambient air temperature. Fasteners, clips and perimeter connections should be designed and installed to accommodate the anticipated thermal movement of the panel. If panel expansion/contraction is inhibited by perimeter flashing conditions or inadvertent “dual pinning” at other details, the result can be seen as oil canning. Waviness caused by thermal forces differs from the other forms of oil canning in that waves can appear and disappear daily as the panel temperature varies due to solar absorption or radiation.
Improper Storage & Handling – For certain types of metal panels, storing or carrying panels in a flat orientation, twisting, or buckling panels can induce a wavy appearance to a previously flat panel.
Twisting can occur if one corner of a panel is used to lift a panel or to remove the panel from a bundle or pallet. Manufacturer’s recommendations should be followed.
Coil – Tension (“stretch” or in line) precision leveling is a process that stretches the metal beyond the yield point while the metal is in coil form. Once stretched to this point, the metal will not creep back to its previous, non-level state. This provides a flatter surface less prone to oil canning and may correct inconsistencies of coil production and secondary coil operations. For this reason, tension leveling should be done after secondary operations such as slitting. The effect of oil canning can be reduced by ordering tension leveled material.
Gauge – In general, the thicker the metal (the smaller the gauge number) the less likely a panel is to oil can.
Panel Design – In general, the use of attachment systems that allow panels to move without inducing thermal stresses is another means of controlling oil canning. The addition of stiffening ribs in the panel profile “break-up” the flat surface and may make oil canning less apparent, but may also add minor shadow lines.
Panel Finish – The eye perceives reflection of light, which is why oil canning on a lower gloss surface is less perceptible than a high gloss surface.
Low gloss finish systems or embossed surfaces, which are less reflective, may reduce the visual perception of oil canning seen in the metal.
There is less difference in the appearance of reflected light from a lighter color panel with oil canning than from a darker color panel, which makes oil canning more noticeable on darker colored panels.
Installation Issues – Stringent specifications regarding the alignment of the supporting structure or the deck would focus attention on this critical aspect. Normal trade practices and tolerances concerning the substrate may not be adequate to minimize oil canning of the finished surface. Manufacturer recommendations regarding proper handling, spacing, and fastening of panels should be part of the manufacturer’s installation recommendations. Uses of Backer Rod or Other Similar Shimming Materials – Some designers specify the use of “backer rod” or other similar types of shimming materials on the panel underside when installation is over a solid substrate. Backer rod is a compressible foam strip normally used in the concrete and masonry trades in joints to serve as a backing for a caulk joint. For certain types of metal panel systems it causes the center of the panel to “pillow” uniformly, relieving stress and reducing the visual effects of oil canning.
So, How Can Oil Canning Be Minimized?
Certain designers regard oil canning as inherent to the material and treat it as a desired effect accentuating the material’s natural characteristic, while others do not. Coil producers and panel manufacturers generally attempt to minimize unintentional non-flat conditions. Research continues on improved production and fabrication methods to minimize the oil canning effect within the manufacturing process. The best known way to avoid oil canning is by choosing a thicker gage of metal for the roof, as well as selecting a roof that has striations in the panels to keep them stronger. Whenever you have a thicker gauge of metal this naturally gives you a stronger base for the metal to keep from warping and bending, thus reducing the chances of oil canning from happening. The biggest thing you can do to achieve an oil can free roof is by selecting roofing panels that have striations in the panels. The most common different striations that you can select are pencil striations, flat striations, ribbed striations and block striations.”
Galvanic Corrosion:
Galvanic corrosion is a common issue that can compromise the longevity and integrity of roofing systems. It occurs when two different metals come into contact in the presence of an electrolyte, like water or salt, leading to the deterioration of one of the metals. This electrochemical process can significantly shorten the lifespan of roofing materials if not properly managed.
How Galvanic Corrosion Affects Roofing?
As INTERNATIONAL MIOIYBDENIIM ASSOCIATION describes it, roofs often combine multiple materials, such as metal flashing, fasteners, and underlayment, so when metals with differing electrochemical properties, like copper and aluminum, are paired together, galvanic corrosion can occur if water or moisture acts as an electrolyte. The more “anodic” metal (e.g., aluminum) corrodes more quickly, while the “cathodic” metal (e.g., copper) remains protected. Over time, this corrosion can lead to material degradation, leaks, and even structural damage.
Prevention Tips
- Choose Compatible Materials: When selecting roofing materials and fasteners, ensure they are compatible with each other in terms of their electrochemical properties. Materials like stainless steel and aluminum tend to work well together, whereas mixing copper and galvanized steel can cause problems.
2. Regular Maintenance: Inspect the roof regularly for signs of corrosion, particularly around fasteners, joints, and metal flashing, and address any issues before they become major problems.
Galvalume Metal Roof vs. Aluminum Roof:
Galvalume is a steel-based material coated with a mixture of aluminum, zinc, and silicon. The coating gives Galvalume its corrosion-resistant properties, while the steel base ensures strength. The typical coating consists of about 55% aluminum, 43% zinc, and 1% silicon, which provides protection against rust and weathering.
Aluminum roofing is made entirely from aluminum metal, without any additional coatings or alloys. Aluminum itself is highly resistant to corrosion, especially in harsh environments such as coastal or saltwater areas. It’s lightweight, flexible, and can handle extreme temperature changes without cracking or warping.
The biggest difference between these two materials is how well does either stand up to the elements? Galvalume does not stand up well to salt water and salt water breeze areas. So it is not a good choice for any area at or near the coast. This is because when you cut any sheet to fit into a specific spot, that cut has now exposed the metal to the elements, specifically all the salt in the air, which causes rusting. This is the exact reason why here in Charleston it is known by professionals to use aluminum for a metal roof as aluminum is not affected by the salt and won’t rust out.
Understanding Gauges of Metal for your Roof:
The gauge of metal is a measurement that indicates the thickness of the metal sheet. The lower the gauge number, the thicker the metal. For example: 24-gauge metal is thicker than 26-gauge metal. Gauge numbers generally range from 22 to 29 for metal roofing, with 22 being the thickest and 29 being the thinnest.
Thicker metal (lower gauge) provides better strength and resistance to dents, impacts, and harsh weather conditions (hail, high winds). A thicker metal is less likely to bend, flex, or develop visible deformation (like oil canning), which can be a concern with thinner materials.
Thinner metal (higher gauge) is more vulnerable to damage and may not perform as well in extreme weather conditions or over time, especially if the roof is exposed to heavy impacts or high winds. Thicker metals generally have a longer lifespan because they are more resistant to the wear and tear caused by the environment. While a thinner metal might perform adequately in the short term, it may show signs of rust or corrosion sooner, especially in harsher climates. Thicker panels are also more resistant to corrosion, bending, and flexing, and they are less likely to suffer from oil canning or warping.
Thicker metal panels are heavier, which can be a consideration for installation. While they offer more durability, they may require extra labor or equipment for handling and installation.Thinner panels are lighter and easier to transport and install, but they can be more susceptible to wind uplift and physical damage. Thicker metal typically costs more due to the additional material and manufacturing processes. For example, a 24-gauge panel will be more expensive than a 26-gauge panel. While the initial investment for thicker metal may be higher, it may offer greater long-term value due to its superior durability and lower maintenance costs. Thicker metal may provide slightly better insulation, though the insulation properties are more influenced by the roof’s underlayment and insulation materials rather than the metal gauge itself. However, thicker metals can better handle extreme temperature fluctuations and are less likely to warp or expand, maintaining a more stable roofing system over time.
What are Gauge Options for Metal Roofing?
24 Gauge: Often used for commercial buildings, warehouses, and residential roofs subject to extreme weather. This gauge offers the highest durability and resistance to corrosion, wind, oil canning and impact. It is generally the preferred choice in areas with harsh climates or significant weather events.
26 Gauge: A common choice for residential roofing, offering a good balance of strength and cost. It’s durable enough for most residential applications and provides a long lifespan, though it may not be as resistant to heavy impacts as 24-gauge.
28 or 29 Gauge: These thinner gauges are typically used for builder grade residential or agricultural buildings, where the budget is a significant concern. They are lighter and more affordable, but they may show more wear and tear over time and are more susceptible to issues like oil canning, denting, or rusting in harsh climates like Charleston.
What are the price differences with Exposed Fastener Roofs vs Standing Seam Roofs?
Exposed fastener roofs are cheaper than standing seam roofs for a variety of reasons. Exposed fastener roofs generally use thinner gauge metal, wider panels requiring fewer pieces to cover a roof, and have a simpler installation process that requires less skilled labor, resulting in lower material and labor costs overall; whereas standing seam roofs involve more complex fabrication and installation techniques with specialized components, driving up the price.
Galvalume vs Aluminum
When choosing the type of metal for your roof, many homeowners often make critical mistakes—especially here in Charleston, a location known for its coastal environment. The material your metal roof is made from plays a critical role in its durability and longevity, especially in environments exposed to salt breeze, salty air, and high moisture levels. Through extensive research and data from leading metal roofing distributors, it’s evident that Galvalume metal roofs are not suitable for coastal regions like Charleston. The salt-laden air and high moisture content can cause Galvalume to rust prematurely, leading to leaks and eventual roof failure. Sentrigard Metals, a reputable metal roofing supplier serving the Charleston area, advises contractors against using Galvalume products in this region. They highlight that the salt breeze and coastal air will accelerate corrosion, making Galvalume an unsuitable choice for roofs in Charleston. To ensure the longevity and reliability of your metal roof, it’s essential to choose materials that can withstand the specific environmental challenges of your location. In coastal areas like Charleston, opting for metal roofing materials other than Galvalume will help prevent premature rusting and ensure your roof’s long-term performance.
Galvalume, a combination of steel coated with aluminum and zinc, is widely praised for its corrosion resistance and affordability in inland applications. However, its performance changes dramatically in saltwater environments. Studies and real-world evidence show that galvalume roofs can prematurely rust and degrade when installed within 1,500 to 2,000 feet of the coast or in areas subjected to frequent saltwater breezes. This is due to the chemical interaction between salt and the protective coating, which accelerates the corrosion process. This is also the case as when you cut the panels to fit in spaces, it exposes the metal to the elements (the salt in the air) which also drastically accelerates the rusting process. Simply put, if you live in Charleston or any coastal area, a galvalume roof is not a wise choice for long-term durability.
In contrast, aluminum is a far better option for metal roofs in coastal environments. Unlike galvalume, aluminum is inherently resistant to rust and corrosion, even in areas with high salt content in the air. Its lightweight nature, combined with its superior corrosion resistance, makes aluminum roofing an ideal choice for homes near the coast. While aluminum may come with a slightly higher upfront cost compared to galvalume, the added durability and reduced maintenance requirements make it a worthwhile investment for homeowners in Charleston.
To summarize, the key difference lies in how each material handles exposure to salty air. Galvalume is affordable and effective at handling inland environments but prone to premature rusting and corrosion in coastal areas due to its vulnerability to salt exposure. Aluminum however, is naturally rust-resistant and better suited for the harsh environment of coastal regions, providing a longer lifespan and better performance over the long haul. For Charleston homeowners, the choice is clear if you want a roof that will withstand the challenges of the coastal environment, aluminum is the superior material. Avoid the costly mistake of installing a galvalume roof in an area where it will fail and choose wisely to protect your investment and ensure your roof lasts its expected lifespan
Conclusion
Metal roofs offer numerous benefits, including durability, energy efficiency, and aesthetic appeal. By understanding the different types and their advantages, homeowners can make informed decisions that ensure long-lasting protection and value. Consulting with a professional roofer can provide personalized advice, ensuring you select the best standing seam metal roof for your specific needs and preferences, but the choice is clear in that an Aluminum roof is the best route to go to ensure a rust free strong roofing system for years to come.
