If you’re thinking about installing a metal roof, you may have heard of two different types of steel-based options: galvalume and galvanized steel. What are the pros and cons of each and how do they differ from one another? Read on to learn which option might be best for your roofing needs.
Introduced in 1972 by Bethlehem Steel, the galvalume process blends a steel base with zinc, silicon and aluminum where steel sheets are hot-dipped in zinc and aluminum alloys. This combination prevents corrosion and oxidation. The special zinc coating also keeps any scratches on the metal from rusting over time.
While galvalume is relatively new, galvanizing has been commonly used for nearly two centuries. With galvanization, carbon steel is dipped in hot molten zinc, creating a durable alloy coating that fights corrosion. Once very popular, galvanized metal has become harder to find with the advent of galvalume.
Although both processes are similar, there are some noteworthy differences and limitations associated with each material option.
Due to their zinc coatings, both galvanized metal and galvalume are corrosion-resistant. If galvalume’s coating is scratched away or wears down over time, however, corrosion can occur. Galvalume’s biggest advantage over galvanized metal is the inclusion of aluminum, which is resistant to corrosion.
Although galvanized metal is resistant to corrosion, it isn’t as effective as galvalume. It also tends to form red rust whenever the zinc coating is scratched. Because galvalume provides superior durability and corrosion resistance, most metal roofing has moved from galvanized to galvalume.
Galvalume steel is typically used in industrial environments. It’s also commonly used for walls and roofing for both residential and commercial buildings. That said, it’s generally not suitable for metal roofing for structures with animal confinement since manure-related gas emissions can degrade the metal coating.
Galvanized metal is commonly used for an array of similar applications, but can be more difficult to install. Similar to galvalume roofs, galvanized metal performs better in dry climates where excess water and salt are less of an issue.
For galvalume steel roofs, you can expect to pay somewhere between $75 and $200 per square. While it’s pricier than asphalt shingles, galvalume is actually relatively inexpensive compared to other kinds of metal roofing materials. Although galvanized steel is made in a similar manner, it does tend to be more expensive. You can expect to pay around $150 to $350 per square for a galvanized metal roof.
Galvalume steel siding and panels often come with warranties that protect against rust as long as it isn’t limited to the surface. That said, some companies will not provide protection for homeowners who live in coastal climates where the material is subjected to excess water and salt.
One of the biggest drawbacks of galvanized metal roofs is limited or nonexistent substrate warranties, due to the material’s unpredictability in certain climates.
Both galvanized and galvalume roofs have a longer lifespan compared to most roofing materials. That said, galvalume panels can last up to six decades with minimal repairs, while galvanized steel has a lifespan of 50 years or less, depending on the local climate.
Pros and Cons
Cost-effective – Although metal roofs are usually more expensive than other roofing systems, galvanized metal and galvalume roofing tend to be more cost-effective than most other metals, including standing seam metal roofs. In fact, a standing seam roof may cost twice as much per square foot compared to steel.
Resistance to Corrosion
While both galvanized and galvalume panels resist corrosion, galvalume offers added protection due to the presence of aluminum, which is naturally resistant to rust and corrosion.
Both galvanized and galvalume roof panels are very lightweight with an impressive strength-to-weight ratio. They don’t crack easily and are much easier to work with compared to other metal roofing options.
Galvalume roofing has a sort of “self-healing” characteristic that stops the spread of rust with the help of an acrylic galvalume coating or paint. Galvanized steel doesn’t have this quality and is prone to rusting whenever the topcoat becomes scratched.
Both galvalume and galvanized steel roofs are incredibly energy efficient due to their ability to reflect solar radiant heat.
The biggest drawback of galvalume panels centers on oil canning. Oil canning occurs when flat surfaces of wall or roof panels appear distorted or wavy. While it may not signify actual structural damage or poor material quality, it’s not aesthetically pleasing.
Need help installing a durable, long-lasting metal roof? For decades, the professionals at A to Z Roofing have served countless satisfied customers throughout the Denver metro and the Front Range. For nearly a quarter of a century, we have been the go-to source for expert residential roofing, repair and restoration for homeowners and businesses throughout Colorado. During this time, we’ve provided comprehensive service using only top-quality products. Contact our attentive team to learn how we can restore, repair or replace your damaged or aging roof.