Both galvalume and galvanized steel are corrosion-resistant steel coatings. But this doesn’t mean they’re one and the same.
While there’s no universal “best” option, various factors, such as environment, use, and application, may determine whether one is suitable or the other. Below, we compare galvalume vs galvanized steel in more detail.
What Is Galvanized Steel?
Galvanized steel is made by submerging steel in molten zinc through a process called hot-dip galvanizing. This forms a protective zinc coating that bonds across the entire surface.
This zinc protects the steel from corrosion caused by water or oxygen. If this coating becomes scratched or damaged, the zinc corrodes, not the steel underneath. This durability is why galvanized steel has been commonly used in construction, framing, fencing, and even agricultural practices for decades.
On top of the above, galvanized steel is affordable, easily accessible, and can be used in various environments. With age, the zinc coating may develop a matte appearance, but this doesn’t impact function and is generally only cosmetic.
What Is Galvalume Steel?
Instead of pure zinc coating, galvalume steel is coated with an alloy of roughly 55% aluminum, 43.4% zinc, and 1.6% silicon. This provides corrosion prevention from multiple angles.
First, the aluminum forms a thin oxide layer that resists moisture. Meanwhile, the zinc offers the same protection as it did for galvanized steel. In other words, it helps prevent corrosion caused by water or oxygen. Often, galvalume steel offers extended protection when compared to galvanized steel due to its use of two different metals. In fact, it’s very much a standard in the metal building industry for both roofing and exterior wall panels.
How Corrosion Protection Works
While both of the coatings offer protection, how they do this slightly differs.
Galvanized steel depends upon sacrificial protection (zinc behavior), which means the zinc corrodes first before any damage reaches the base metal. This means that even at vulnerable spots, such as cut edges and fastener holes, the steel stays protected.
In contrast, galvalume steel uses barrier protection (coating coverage). The aluminum-rich coating resists surface corrosion across large flat areas and holds up well when the surface stays intact. However, it’s worth noting that its edge protection is more limited.
At the same time, both types of steel coatings can be impacted by humidity, salt exposure, and temperature swings over the long-term. Again, one isn’t necessarily better than the other, depending on many different factors.
Performance in Different Environments
In dry or mild climates, both coatings tend to perform well.
In humid or rain-heavy environments, on the other hand, galvalume generally provides stronger flat-surface protection due to its aluminum content. But galvanized steel may still be preferred where edge protection matters more.
In coastal areas, exposure to salty air poses another challenge. In fact, it usually accelerates corrosion. Yet, galvalume steel typically resists surface degradation more effectively in these settings.
In industrial or agricultural settings, galvanized steel is often preferred because physical damage to the coating is more likely, and the zinc layer can provide better protection.
Appearance and Surface Characteristics
For many purposes, aesthetics matter. So, what do each of these steel coatings typically look like?
Galvanized steel usually has a bright, spangled look when new, but it also tends to dull into a matte gray patina over time.
Galvalume has a smoother, more uniform finish from the start and generally retains that consistency with age.
In other good news, both options can be painted over. And many metal buildings use pre-painted panels, regardless of the base coating. Inevitably, painting either steel reduces the aesthetic differences significantly. However, the underlying coat may affect paint adhesion and durability.
Applications in Metal Buildings
In metal building construction, components may use different coatings, often due to differences in exposure. For example, roofing and wall panels frequently use galvalume steel, and this is especially relevant in coastal areas. In contrast, more structural components, such as framing, often use galvanized steel.
Many providers, including companies like US Patriot Steel, use both coatings within a single project to match each component with the protection method that suits it best.
Cost Considerations
With any building project, balancing your budget with long-term value is often a juggling act. Put simply, galvalume panels often carry a slightly higher material cost than galvanized panels due to additional processing.
With that said, your overall project cost will depend on many factors, including building size, design, insulation, labor rates, and more. The steel coating ultimately only reflects a fraction of your total costs.
On top of this, availability can play a role in your choice, with galvalume steel often taking longer to source in some regions.
How to Choose Between Galvalume and Galvanized Steel
When selecting galvalume vs galvanized steel, start with your environment and potential exposure. If the building will be in a coastal, humid, or rain-heavy area, Galvalume is often the more practical choice for exterior panels and roofing. For inland or dry climates, both options can work.
Next, you’ll want to address the intended use of the building when making your final decision. For agricultural buildings, such as those that have livestock contact or equipment scrapes, galvanized steel’s sacrificial protection is the better fit.
For workshops, garages, or commercial structures where appearance and surface durability matter more, Galvalume may be the stronger choice, especially since it tends to hold a cleaner, more consistent look over time.
When in doubt, consult with a metal building provider, such as US Patriot Steel. We can help determine the right steel coating for your project, matching it to your needs and budget.
Frequently Asked Questions
Neither option is “better” than the other. Galvalume typically offers stronger flat-surface corrosion resistance, but galvanized steel provides better sacrificial protection at edges and damage points. Your choice will ultimately depend on your specific use, location, and budget.
Yes, galvalume steel can rust if the coating is very scratched or damaged and the base is exposed. Coastal environments or other aggressive climates may also speed up the corrosion of this material.
Galvalume is often used for roofing. This is because it provides a corrosion-resistant surface over large, flat areas. In fact, many companies consider it the standard, but, in some cases, galvanized steel may also be used.
Both offer fairly low-maintenance options. With galvanized steel, minor scratches take care of themselves; the surrounding zinc corrodes first, protecting the exposed steel underneath. Galvalume doesn’t provide the same protection at cut edges, so in corrosive environments, those spots may require sealing or touch-up. Either way, regular inspection is always a good idea for any building and its components.
Yes, both are in line with building codes. Yet, this can vary from region to region, so it’s a good idea to check for your specific area first or to working with a building manufacturer who can determine what’s best for your location.