Category Archives: Materials

Galvalume vs. Galvanized Steel Roofing – What’s the Difference?

If you are one of the many homeowners looking to install a steel roof on your home, understanding the difference between galvanized steel vs. Galvalume is essential to getting the top performance you expect from your new metal roof.

Right off the bat:

In most residential steel roofing applications including near-coastal areas — beach homes located near the shore, and even homes located in the middle of heavy salt-spray — severe marine environments, Galvalume steel will be a better and more corrosion-resistant option than galvanized steel.

The one exception when Galvalume should not be used:

Galvalume steel should not be used on, in, or around concrete or mortar. Concrete and mortar are highly alkaline environments.

Did you know? Bare Galvalume steel and painted Galvalume sheets will suffer rapid corrosion when in contact with mortar and concrete.

Bare Galvanized steel and painted Galvanized perform better in this type of environment.

Now, because aluminum, one of the two metals in Galvalume coating, provides a barrier protection for steel, instead of galvanic or self-healing protection in galvanized steel, scratches and cut edges in Galvalume are less protected.

Galvalume steel is best for use in prefabricated metal wall panels and standing seam metal roof applications with concealed fasteners.

We would not recommend using Galvalume panels with exposed-fastener steel roofing systems such as corrugated or ribbed steel roofs.

Normally, Galvalume is offered in both bare and pre-coated (pre-painted) versions. Most residential-grade Galvalume metal roofing products – like galvanized steel – are coated with Kynar 500 or Hylar 5000 paint finishes.

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Galvalume has an excellent performance lifespan in bare exposures (unpainted panels) as well.  Both galvanized steel and Galvalume weigh 100 to 150 pounds per 100 square feet and contain about 35% recycled steel post-consumer content.

The cost of Galvalume and Galvalume Plus are about the same as that of galvanized steel.

A product called Galvalume Plus features an extra coating of acrylic. One advantage of Galvalume Plus is that it can be roll-formed dry, without vanishing oil. Thus, Galvalume Plus is very easy to form and install safely in the field, using portable roll-formers.

What is galvanized steel:

Galvanized steel was invented and developed for commercial use in the first half of the 19th Century, so it has nearly 200 years of proven track record. Carbon sheet steel is dipped in molten zinc. It’s more than a coating, however. A chemical bond occurs and produces the telltale “spangles,” the crystalline surface pattern found on galvanized steel.

Tip: Look for G-90 galvanized steel for residential applications not G-60

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Corrugated Metal Vs. Standing Seam – Myth Busters

Who Invented the Original, Corrugated Iron / Steel Roofing Style?

Henry Robinson Palmer learned his civil engineering under Scotsman Thomas Telford, the greatest builder of roads, canals and bridges in the British Empire in the early 19th century.

Standing Seam Vertical Panels

In 1821 Palmer applied for a patent for a single elevated rail supported by pillars spaced ten feet apart that sported wheeled carriages hanging down from either side that would roll along the rail when pulled by a horse. Henry Robinson Palmer had invented the world’s first monorail.

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If you research Palmer’s life today, every source details the creation of the monorail. For most thumbnail sketches of Palmer’s life that is the end of the story, but Palmer himself did not concern himself much with the monorail after building the first one in 1825, about one mile long, in Cheshunt, a town twelve miles from London.

Two years later the 32-year old Palmer landed a job as resident engineer for the London Dock Company. It was his responsibility to construct the walls along the Thames River to keep the world’s busiest port humming.

The aging wooden docks were in constant need of upgrade. To keep up Palmer patented a lightweight metal building panel that was self-supporting due to a series of waves or folds molded into the sheets.

Palmer’s manufacturing process consisted of pushing his sheet metal across fluted rollers to create the ridges that gave the metal strength. He called this “corrugation”, from the Latin word for “wrinkled.” It remains a common method for manufacturing corrugated metal today.

Palmer erected the world’s first corrugated building on the Thames River docks in 1829 and he continued to patent improvements in the construction of arches and roofs.

It is ironic that today Henry Robinson Palmer is remembered for the invention of the monorail, which is rarely encountered outside of amusement parks, airports and a classic Simpsons episode. He is scarcely recognized for the development of corrugation, which became so ubiquitous in the 19th century for cheap shelter that most people – and historians – assumed it had been with us since antiquity.

Historical Significance of Corrugation

corrugated metal roof

Without corrugated metal there would have been no rapid development of the United States frontier, a less frantic California gold rush, much slower settling of farm land on the Great Plains and much harsher living conditions on the battlefield.

The strength to materials imparted by corrugation extended beyond the metal sop to other industries; it was critical to the development of the cardboard, for instance.

Metal Roof Construction

metal-roof-on-a-log-home

By stiffening the metal sheets, corrugation permits a greater span across a lighter framework, ideal for the balloon construction techniques that became widespread in the 19th century.

But metal for roofing has been used for centuries, although it was rare in early America. Thomas Jefferson was a metal roof fanboy and installed tin-plate iron on the roof of his beloved Monticello in rural Virginia.

A metal roof could be fabricated with shingles or a “standing seam,” a technique which involved folding the edges upwards and laying the sheets over one another. Fasteners would hide under the upraised ridge where the sheets interlocked, producing clean, aesthetically pleasing lines.

monticello roof

Metal Shingles Vs. Standing Seam Vs. Corrugated Metal Sheets

Steel Shingles Roof

While metal shingles are also available today and can be produced to mimic any material, standing seam and corrugation remain the two most common types of metal roofs. Let’s have a look at them side by side as you consider your upcoming remodeling project.

elegant standing seam metal roof By Gast Architects

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Materials

The earliest metals used in roofing were lead and copper. Both could last for centuries, which is fortunate since those metals are prohibitively expensive. Today, lead is most often found in roofing as a coating for steel and copper is mostly reserved for flashing or architectural details.

Tin and its close cousin terne, a lead-tin mixture that appears lackluster (hence its French name which translates as dull), were the most common metal roofing materials of the 19th century and are important in authentic historical renovations.

Zinc had a brief run of popularity in the early 1800s as a roofing material, but it became most critical to metal roofing in 1837 when French metallurgists coated iron and steel with zinc to invent galvanization and (mostly) rust-proof metal.

In the 21st century, galvanized steel is the go-to metal roofing material. It is the least expensive roofing material and can be coated in many ways for appearance. Corrugated metal can be fabricated from a G-60 steel that is thinner grade and less expensive.

Standard standing seam roofs can be made from G-90 grade steel, a higher-end Galvalume steel, or aluminum.

Galvanized steel is fabricated in a range from 9 gauge (0.1532 inches) to 32 gauge (0.0134 inches). Standing seam metal panels typically begin as rolls of 24-gauge steel (G-24) or the thicker 22-gauge (G-22) before ferrous metal coatings are hot-dipped.

Corrugated steel paneling can be formed from G-26 or G-29 steel, which makes its cost less expensive; standing seam roofs will never use steel thinner than 26-gauge.

standing-seam-panels

Even galvanized steel can corrode. Galvalume is a trademarked product from U.S. Steel that takes carbon steel and coats it with an aluminum-zinc alloy that performs like galvanized steel on steroids.

But even Galvalume will eventually lose the corrosion battle against the salt spray of ocean near the coastal regions. In such cases, aluminum is the metal of choice. Although more expensive than steel, initially, aluminum’s longer life expectancy helps level the eventual bottom lines.

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Tamko vs. Owens Corning Roofing Shingles: Cost, Pros & Cons, ROI 2019

Owens Corning and Tamko are two asphalt shingle manufacturers sharing the adage, “we’re second-best, so we try harder.” CertainTeed is the consensus leader for overall asphalt shingle quality.

GAF is the largest producer of shingles, and its products get high marks. Right behind those giants are Owens Corning, certainly one of the most recognizable names in roofing products, and Tamko (or TAMKO), a brand that has its fans, too.

The Bottom Line from the Beginning

The bottom line, which all the details in this guide lead to, is that the Owens Corning vs. Tamko comparison is about as even as it gets in the roofing products industry.

Owens Corning Roofing Shingles Display

Both get ratings in the “good” to “very good” range from roofing contractors who install them every day and from home inspectors who have seen their share of durable shingles and shingles that have failed before they should.

What it comes down to is the quality of the installation. You’ve got two above-average shingle brands that can deliver superior durability for 20+ years, fail in just a few years or perform somewhere in the middle.

What makes the difference is how well the installers do their job.

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More on the installation below. Along the way we’ll address where each brand has bragging rights. While OC and Tamko are close to equal in total score, each brand has strong and weak points.

OC vs. Tamko: Quality and Reliability

Quality is a product of the materials used and the production process. Here’s an overview of Owens Corning and Tamko shingle construction.

  • Owens Corning: OC makes three tiers of shingles in basic (Oakridge, Supreme), better (Duration, OC’s best-seller) and best (Devonshire, Woodmoor, Woodcrest, Berkshire) categories.
  • Tamko: This brand makes a very similar lineup with basic (Elite Glass-Seal), better (Heritage, Heritage Woodgate) and best (Heritage Premium, Heritage Vintage).

All shingles from Owens Corning and Tamko feature fiberglass mat bases saturated with asphalt and dressed with coated granules to resist the sun’s UV radiation. Each shingle is constructed with fused layers.

When installed, less than half of each shingle is exposed. The result is that 3-tab roofs (OC Supreme and Tamko Elite Glass-Seal 3-tab) have 2-3 layers of coverage at any given point on your roof.

All other shingles from both brands are architectural style shingles with 4-5 layers of coverage. The result are shingles with wind ratings of 60mph for 3-tab products and 110/130mph for all others.

The two brands have the same ratings in most ASTM materials and fire rating tests. Both are on par or superior to most other brands including CertainTeed and GAF.

Bad shingles are often the result of production rather than the materials used. The production processes for these brands are similar. The processes are slightly tweaked, even from run to run (runs of shingle batches).

When errors occur, a bad batch of shingles, such as layers that don’t properly fuse, are produced. What makes a brand worth considering is the consistency of the quality from run to run. Owens Corning and Tamko deliver good consistency.

Advantage—Tie: We’re not afraid to take sides, but there’s no clear winner here. These brands are rated about as equal as you will find in terms of quality and reliability, especially the two most-popular series, the Owens Corning Duration and Tamko Heritage.

Owens Corning vs. Tamko: Cost

Since these brands compete aggressively head to head, their prices are comparable across all products (and are very competitive with GAF, too).

Here is a breakdown of the shingle series and their costs from both brands:

Prices are per square, which is 100 square feet of coverage (and 3 or 4 bundles of shingles, so check product specs for the bundles-per-square).

3-tab shingles:

  • OC Supreme: $70-$85
  • Tamko Elite Glass-Seal: $72-$77

Average architectural/dimensional shingles:

  • OC Duration: $110-$120
  • Tamko Heritage: $84-$100

Best-selling architectural/dimensional shingles:

  • OC Duration Designer, STORM & COOL: $105-$135
  • Tamko Heritage Premium: $90-$105

Premium, architectural/dimensional shingles:

  • OC Devonshire, Woodmoor, Woodcrest, Berkshire: $175-$280
  • Tamko Heritage Woodgate, Heritage Vintage: $180-$205

Advantage – Tamko: As you can see, Tamko offers better value in each tier of products. It always makes sense to get written estimates on the specific roofing materials you’re considering, to get a direct comparison of cost.

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