How to Decide Which Metal Is the Best Choice for Your Roof

Aluminum, Galvalume, Galvanized, and Copper are the most common metals used in metal roof installation

The avatar of Rachel Polant

Rachel Polant

Mar 15

There is more than one type of metal you can put on top a roof

When you’re considering installing a metal roof on your home, not only do you need to think about the style, such as standing seam, corrugated, metal shingle, or even shake, you also need to keep in mind the type of metal as well.

There are four common metals used in roofing materials, and some of them lend themselves better to certain roofing styles or environments than others. Below is a basic yet informative rundown on the residential roofing metals available for installation.

Aluminum Roofing

Aluminum was once considered a precious metal; but luckily, today it is a common, durable, and versatile material that’s used for everything from cookware to roofs. Lightweight and resistant to rust, aluminum is a great residential metal roofing option. Standing seam, shake, shingle, tile, and slate profiles. are all available in aluminum.

Because aluminum doesn’t really rust, it’s an ideal metal for a coastal area or where a steel roof might be more easily compromised. Aluminum’s ability to resist rust gives it an extremely long lifespan.

The majority of aluminum roofing is prepainted and can be found in pretty much any roofing style that’s manufactured. Another great benefit of aluminum roofing is that a large percentage of it comes from recycled material — the majority of which is post-consumer material such as used beverage cans.

  • Advantages: Lightweight, rust free, attractive, energy efficient.
  • Disadvantages: More expensive than steel. Not as hail resistant, particularly in less-sturdy styles.
  • Thicknesses: .019” for shake, shingle, and tile. Minimum .032” for standing seam and for some heavier tile profiles.
  • Weight: As low as 45 lbs. per square.
  • Recycled Content: Usually around 95% (mostly post-consumer).

Galvalume Steel Roofing

Galvalume steel is base carbon/iron steel coated with an alloy of aluminum and zinc. When aluminum is added with zinc, both of the positive and negative attributes of aluminum are magnified. So, like aluminum, it’s very corrosion-resistant, but also like negative qualities of aluminum, galvalume isn’t as scratch resistant as galvanized steel.

Galvalume steel is also susceptible to an effect known as “tension bend staining.” When steel is formed into the various metal roofing styles, the galvalume zinc/aluminum and the galvanized zinc coatings are spread thin over the metal where there are deep folds or tight bends. It can be so thin that it can form microscopic cracks.

Galvanized steel is able to protect against these scratches due to the galvanic action of zinc. However, with galvalume steel, the aluminum in the alloy tends to neutralize zinc’s galvanic properties, making it less able to self-protect against the cracks and other scratches.

Galvalume steel is used mostly in standing seam roofing because there isn’t quite as much bending in the metal. Because galvalume steel doesn’t corrode like galvanized steel can, it’s sometimes installed unpainted or with a low-cost acrylic clear coat. Unpainted galvalume is bright and shiny, which is not appealing to most homeowners, luckily though, most is painted for added appeal and versatility in aesthetics.

  • Advantages: Very corrosion resistant, strong, relatively inexpensive (but often slightly more expensive than galvanized).
  • Disadvantages: Susceptible to tension bend staining, limited profile availability (mostly standing seam or simple shingle styles), must be cut with a shearing action rather than saw-cut.
  • Thicknesses: 24 gauge (.024”) is most common for standing seam systems.
  • Weight: Between 100 and 150 lbs. per square (100 sq. ft.).
  • Recycled Content: Usually around 35%.

Galvanized Steel Roofing

Steel metal roof

Because the traditional carbon/iron steel alloy is rust prone when exposedto the elements, steels used for the metal roofing industry are coated with another metal or alloy on both sides of the base carbon/iron steel strip. The two ways to achieve this are through either the hot-dip process or electroplating. The hot-dip method is cheaper and more efficient than electroplating.

Galvanized steel is available in most metal roofing profiles. It costs less than most other metals, it’s strong, and it holds paint very well. Scratches on galvanized steel have a “band-aided” effect that keeps the steel from rusting.

The lifespan of galvanized steel depends largely on the thickness of its metallic coating. G-90, the most common zinc thickness used in the metal roofing industry, means that 0.90 ounces of zinc are coated per square foot of steel surface. Lesser grade-galvanized steels are G-30 and G-60, and these should usually be avoided for residential use. Always check the manufacturer’s specifications to determine the thickness of the steel’s metallic coating.

G-90 only refers to the thickness of the zinc coating and not the thickness of the steel itself. The thickness of steel is measured in gauge number, such as 26 Gauge, 24 Gauge, etc.

Galvanized steel is not a good option for homeowners in coastal areas. Salt spray and other elements can speed up corrosion and shorten its life. But, in general, galvanized steel is a great choice for residential properties.

  • Advantages: Strong, lower cost, comes in almost any look.
  • Disadvantages: Shorter life span than other metals, can rust prematurely if not used or installed properly, can be more difficult to work with, must be cut with a shearing action rather than saw-cut.
  • Thicknesses: 26-28 gauge (.018” – .014”) is the most common for shake, shingle, tile, and slate profiles. 24 gauge (.024”) is most common for standing seam systems, with a good amount of 26 gauge as well.
  • Weight: Between 100 and 150 lbs. per square (100 sq. ft.).
  • Recycled Content: Usually around 35%.

Copper Roofing

Copper roofing accents

Copper is one of the most beautiful roofing materials. But, that beauty comes with a big price tag too. Due to its expense, it’s rare to find it used over an entire roof. Copper is mainly used as an accent over bay windows, dormers, or any area where an added architectural element of interest is wanted.

Copper is typically installed in short standing seam panels or sheeting, but copper shingles are available too.

You’ll often see copper used as a flashing material in conjunction with slate. However, copper should not be used with aluminum or steel roofing. Not just because residential metal roof systems come with their own pre-made flashings, but, more importantly, because when copper is in contact with a dissimilar metal, it will speed up the deterioration of the other metal through galvanic action.

As the copper patinates (turns green), the water runoff is apt to stain other metal, brick, concrete — pretty much anything it comes in contact with. So, it’s important to understand where the water runoff is directed and how it runs off the roof.

Copper is best known for its attractive blue-green patina that forms after 8-15 years, depending on the nature of what’s in the air, like sea spray. The patina actually creates a barrier against corrosion and is part of the reason for copper’s longevity — more than 100 years!

Recent coatings technology has brought homeowners the option of choosing steel or aluminum roofing that has been coated to resemble copper. Finishes are available from bright “new” copper to fully weathered copper, as well as coatings designed to look like copper in varying stages of the patination process. Classic offers several colors along this line on its aluminum roofing systems, giving homeowners an option of the permanence of copper at a lower cost.

  • Advantages: Beautiful, extremely durable, easy to work with, easily solderable.
  • Disadvantages: Expensive, runoff will streak or stain other materials, natural patination takes time.
  • Thicknesses: .12 oz. (.016”) and 16 oz. (.022”) are common for pre-formed shingles. 16 oz. (.022”) and 20 oz. (.027”) are common for vertical seam.
  • Weight: Between 100 and 150 lbs per square.
  • Recycled Content: Varies but is often around 35%.

Hire qualified, licensed and insured metal roofing contractors for your metal roof installation job

Regardless of what type of metal you pick and your choice of roofing style, it’s even more important to hire an experienced metal roofing contractor to install your roof correctly.

A metal roof is an investment in your home. Metal is more expensive because it lasts decades past other common roofing materials, like asphalt. Because you pay more for its durability and longevity, you don’t want your hard-earned money wasted due to hiring a shoddy roofing contractor. Not only will you have wasted all that money on your metal roof the first time, but you’ll also have to pay even more money again in the near future to have it repaired.

Be sure to vet out metal roofing companies, get multiple quotes, and only hire a business that is licensed and insured.


The avatar of Rachel Polant

Rachel Polant

Mar 15