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Metal Roof Systems: Discover the Possibilities


Author: Toy Henson
Date: Jan 1 2008 12:00AM
URL: www.themetalinitiative.com


When commercial building owners and developers require an attractive and affordable roof for their projects, chances are more and more of them are choosing a metal roof.

The reason is simple: Metal roofs have been a preferred covering for commercial buildings for centuries because of their ability to protect the structure from the elements and to shelter its occupants and contents.

In more recent times, however, building owners have come to recognize and appreciate still other attributes of metal roofs–their beauty, long service life, low life-cycle cost, light weight, sustainability, recyclability and low maintenance requirements.

So if you’re not familiar with metal roof systems yet, here are some basics you need to know about their use and selection.

Low Slope, Steep Slope

Metal roof systems are divided into two categories–low slope and steep slope. Low-slope roofs are used on roof pitches from 1/4:12 to 3:12. They are commonly made from steel and consist of interlocking panels applied directly over bar joists or purlins. Low-slope roofs are generally not very visible from ground level.

Steep-slope roofs are used on roof pitches of 3:12 or greater and divided into two categories: structural and architectural. Structural steep-slope roofs are usually applied over open framing but can be installed over a solid deck, while architectural steep-slope roofs always require a solid deck. Steep-slope roofs are usually made from steel, aluminum, copper or zinc and are visible from ground level.

Regardless of whether it’s a low-slope or steep-slope application, the features and benefits inherent in metal roof systems make them very viable choices for use on commercial buildings of all types, from hospitals and corporate headquarters to schools and retail centers. Here are some of the reasons why.


Design Flexibility

Today’s metal roof systems can bring added drama and imaginative design to the exterior of any building. That’s because they’re offered in a wider choice of options today than ever before to help create more visually interesting buildings.

Metal roofs offer virtually unlimited architectural creativity with a vast array of shapes, styles, profiles, textures and an ever-growing palette of colors, ranging from standard hues to custom-matched tones. They adapt to styles ranging from traditional to contemporary and enable buildings to stand out or blend with their environments.


Low Environmental Impact

Metal roof systems are also an environmentally responsible choice for buildings of all types. That’s because they typically have a recycled content of at least 25 percent, and the metal is 100 percent recyclable at the end of its useful life, thereby contributing to the recycled content of future products. Metal’s recycled content can even help earn LEED points in the Materials & Resources category.

Metal roofs are also sustainable. Their extremely long service lives lower the demand for energy and raw materials to produce replacement systems. And in many retrofit applications, metal roofs can be installed over old flat roofs, thereby eliminating the need to remove the old roofing and preserving landfill space.


Extremely Durable

Today’s metal roof systems are exceptionally durable. Many are warranted up to 30 years, some even more. That’s because today’s high-performance paints and coatings are designed to protect the metal panels for decades, while the patina that forms on noncoated copper and zinc panels protects the metal from the elements naturally.

Today’s generation of paints and coatings also help metal panels retain their appearance, ensuring that the building maintains its aesthetic appeal and property value over time.


Lower Construction Costs

Metal roof panels are lighter in weight than most other roofing choices. As a result, they can often help lower construction costs by reducing framing and foundation requirements because less structural support is needed.

Construction costs may also be lowered because metal panels can usually be installed faster than other materials. That’s because their installation is not slowed by weather conditions. This all-weather capability minimizes delays, gets the building closed-in quicker and speeds up completion. And faster completion means quicker occupancy.


Lower Energy Costs

Lower construction costs aren’t the only way metal roofs can improve the bottom line. Lower energy costs are another. For example, an increasing number of local, state and/or federal initiatives and codes are now requiring that roofs on commercial buildings have a minimum solar reflectivity and thermal emissivity in order to reduce energy consumption by lowering air-conditioning loads within the building. Roofs that meet these requirements are called “cool roofs” because they have lower surface temperatures.
As a result of new developments in pigment technology, painted metal roofs perform very well as cool roofs and can provide a very energy- and cost-efficient solution, as evidenced by research conducted by Oak Ridge National Laboratory, Oak Ridge, Tenn.
For example, results of a three-year study showed that painted metal roofs retained 95 percent of their initial solar reflectivity values over time. This is important because some codes assume reflective performance of all roof material degrades at the same rate.
The same study showed that some membrane systems lost 40 percent of their solar reflectance after only three years due to dirt retention. Metal roofs shed dirt more readily than other roofing materials, which is important, because the dirtier a roof, the more its reflectance is compromised.


Low Life-cycle Costs

Metal roofs have long been considered the most cost-effective roof systems. Now there’s proof, thanks to a study conducted by the Ducker Organization, an independent research organization based in Troy, Mich., that specializes in the construction industry.
Building owners who participated in the study said they expect low-slope metal roofs to last 40 years–17 years longer than built-up roofs and 20 years longer than single-ply systems.
They also said they expected the life-cycle cost of a metal roof to be about $0.30 a square foot per year, significantly less than the $0.37 for built-up roofs and $0.57 for single-ply roofs. The life-cycle cost of a roof is determined by computing the present value of all costs associated with the roof over time, including original cost of the roof, regular maintenance activities and any repairs.


Low Maintenance Costs

When it came to maintenance, study participants who owned metal roofs said they spent less than 4 percent of the total installed cost on maintenance compared to 19 percent by owners of built-up roofs and 28 percent by owners of single-ply roofs.
And perhaps most importantly, when asked if they would use the same roofing material in the future, 92 percent of the metal roof owners said they would, compared to 46 percent of the built-up owners and 58 percent of the single-ply owners.
Discover Metal’s Possibilities

Now that you’ve seen the possibilities of today’s metal roofing, imagine what metal can bring to your next building. Metal roof systems offer more innovative design options, more durability and greater cost efficiency than you may have thought possible. When properly chosen and installed, they are indeed cost-effective, attractive, long-lasting, easily maintained and environmentally friendly building materials.
For help in creating a building exterior that’s visually unforgettable and surprisingly affordable, visit www.themetalinitiative.com. There you’ll find even more information about metal’s architectural advantages, life-cycle costs, case studies, photos, news, related links and more.
Toy Henson is director of education and market development for The Metal Initiative.
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