Tag: water tight

Roofing and Snow: Everything You Need to Know – Part Two

Posted on by Ken Buchinger

Additional considerations for working with metal panels in winter.

In part one of our series on metal roofing and snow, we covered five of the most important elements to consider when preparing structures for winter weather. In this post, we’ll review four more ways to prevent unexpected, costly damage of metal panels in winter.

  1. Consider roof material and surface color

Metal roofs absorb heat quickly and radiate it effectively. Darker panel colors can enhance this solar absorption effect, which can save you money year-round. But because UV light can pass through 3-5 inches of snow, when combined with heat loss through the roof, it becomes more difficult for snow to stay solid. To minimize the chance of ice damming, you should ensure your roof system is properly sealed and insulated. If not, ice damming may occur and the melting and re-freezing of snow throughout the day can result in icy layers that promote snow sliding—no matter the roof material or color.

  1. Review weathertightness factors

For low-sloped roofs (less than 3:12), it is especially important for panel seams to be watertight to prevent water (melted snow) from leaking into the structure. This can be problematic when snow gathers and stays on a roof. Architects, designers and specifiers, therefore, should consider using panels that have passed the ASTM 2140 water head test or FM 4471 Appendix G water test. Water-resistant underlayment should also be considered for all roof slopes.

ABC Blog: Roofing and Snow: Everything You Need to Know about Metal Panels in Winter - Part Two
A close-up of this dormer roof illustrates how the impact of sliding ice and snow can damage panel seams.
  1. Consider your roof layout

Design elements like valleys and slope changes cause snow to collect and increases your snow load. Also, when dormers extend from a large roof area and one area is significantly bigger than the other, the structure is susceptible to experiencing unbalanced sliding snow. This imbalance can actually tear open standing seams and displace panels. Also consider that drifting snow may accumulate behind HVAC units, at perimeter walls, and behind solar and photovoltaic (PV) panels.

  1. Ensure Proper Roof Maintenance

One of the best ways to prevent snow and ice issues is to regularly inspect and maintain your roof. In addition to cleaning and inspecting your roof for possible issues, properly removing standing snow and preventing ice dams is a vital part of avoiding damage to your metal panels in winter. This often requires that you get into your attic to inspect for air leaks—the leading cause of ice dams. Read more about how to properly maintain and remove snow from your roof in this blog post.

If an issue is discovered, consult your roofing material manufacturer for recommendations as well as advice on warranty claims. Additionally, you can reach out to a trusted roofing professional in your area. These professionals can thoroughly inspect your roof system to help you determine ways to rectify any potential issues. You’ll want to do this before damage and/or injury occurs and before you pay for sub-par or ineffective repairs.

If you missed part one of this series, click here for our top five considerations. These include managing snow load and sliding snow, preventing ice dams, using retention systems and more! For more information on how metal panels fare in winter weather conditions and for advice on how to winter-proof your roof, reach out to an ABC representative today.

Galvalume® vs. Galvanized Metal Roofing

Posted on by Jessica Taylor

Galvalume® vs. Galvanized Metal Roofing

Selecting metal panels made from high-quality materials is essential to the longevity and success of your customer’s metal roofing system—from the steel sheets to the fasteners. Although the quality of the paint system applied to metal roofing panels provides an essential level of protection (as discussed in our recent ‘Decoding Your Warranty’ blog series), not to be overlooked is the coating used on metal roofing panels. Two coatings are commonly used on steel sheeting in the metal panel industry today: Galvalume® and Galvanized. Both products are manufactured to adhere to carbon sheeting and provide a barrier that resists corrosion. Additionally, they enhance long-term water-tightness and durability, ensuring resilience through damaging weather conditions. But what exactly are the differences between Galvalume® and Galvanized?

What is Galvalume® metal?

Introduced into the construction marketplace by Bethlehem Steel in 1972 and now widely available around the world, Galvalume® is carbon steel sheeting coated with aluminum-zinc alloy by a continuous hot-dip process. Composed of 55 percent aluminum and approximately 45 percent zinc, this coating combines the best properties of both metals. It has the corrosion resistance, high temperature oxidation resistance and heat reflectivity typical of aluminum coatings, with the formability and galvanic protection of cut edges characteristic of zinc coatings. This combination makes it ideal for most types of roofing and siding. In addition, the coating also contains a small but significant amount of silicon in the alloy—not to enhance the corrosion performance, but to ensure optimal coating adhesion to the steel substrate when roll-formed, drawn or bent during fabrication.

 What is Galvanized metal?

Galvanized Sheet is carbon steel sheet coated with zinc on two sides by a continuous hot-dip process. This method tightly adheres the coating to the steel with an iron-zinc alloy bonding layer formed by a diffusion process while the heated steel strip is in contact with the molten zinc.

What is the difference between Galvalume® & Galvanized roofing?

While both products were developed to essentially sacrifice themselves to protect the steel sheeting they coat, the above exposure comparison shows that Galvalume® performs (up to nine times) better in fighting corrosion as compared to Galvanized coating. While Galvalume® can initially show signs of corrosion faster than Galvanized, it has a sacrificial property that will prevent the corrosion from growing whereas once corrosion has started on a Galvanized panel, it can continue to corrode until panel integrity is lost. According to a study released by the Metal Construction and Zinc Aluminum Coaters associations, the longevity of a low-slope unpainted Galvalume® standing-seam roof is 60 years  (See the full report.)  Additionally, primer and paint adhere better to Galvalume®-coated panels and they carry a 20-year limited warranty while galvanized panels do not, making them a smarter long-term investment for your customers’ homes, agricultural buildings or commercial properties.

Important Facts About Galvalume®

  • Galvalume® should not come in direct contact with: standing water, dissimilar metals (copper, lead, iron), harsh chemicals, graphite pencil, masonry products or treated lumber.
  • Proper roof inspections and maintenance is still required, as with any other roof system.

Its versatility, ease of use, aesthetic appeal and long-term, service life-extending performance makes Galvalume-coated steel roof panels the most economical and sustainable coating option for your customers’ new and retrofit applications. To learn more about Galvalume®, please visit  http://www.galvalume.com/. To view ABC’s Galvalume® Plus products, which are easy to form and install safely due to the thin, clear acrylic coating that allows them to be roll-formed dry without vanishing oil, please see our color resources and Galvalume® warranty information.