Why Asphalt Roofing is Superior to other Roofing Materials, including Metal

With a proven history of value and performance, asphalt shingles are the obvious choice in today’s roofing market

WASHINGTON, D.C. - Asphalt shingles have been the most effective and widely used roof covering for new home construction and reroofing over the last 150 years — in fact, it has been installed on four out of every five homes in the U.S.

This figure should come as no surprise because asphalt shingles give homeowners and builders a wide range of options to choose from in today’s steep-slope roofing market.  And even in today’s challenging economic climate, the market share for asphalt roofing shingles is likely to continue to increase.

Currently, home value declines are equal to what the U.S. experienced during the height of the housing recession. Rising foreclosures and high negative equity rates make it almost certain that we won't see home values bottom out until the end of 2012 or later.

While the news from economists is sobering, it is also upbeat for asphalt shingles. The logic is simple: When the roofs on these devalued homes fail, property owners will seek the easiest and most affordable solution —asphalt-based shingles.

Whether homeowners are in negative equity or not, roof replacement is not a discretionary purchase.

With almost all housing values in flux, and alternative roofing materials proving costly, property owners will opt for asphalt roofing products to protect their investments. The same logic can be applied to builders’ choices in the slumping new construction market.

The choice is yours

Generally speaking, slate, concrete, metal, clay tile, wood shakes and shingles are niche products. Clay and concrete tile are popular in Florida and the Southwest, particularly in multi-housing developments. However, these products are heavy and more difficult to install and most look for some form of waterproofing beneath them (self-adhering or asphalt-coated underlayments) as tiles only shed water, versus asphalt shingles that seal to themselves. In addition, natural slate, concrete and clay tile are usually specified by an architect who will ensure the building has the structural strength to handle the additional weight of the roofing product. After specification, retrofitting may be required for alternative materials whereas asphalt shingles can often be installed over existing home structures. This process of specification and retrofitting can add cost to a typical installation.

Wood shakes and shingles are aesthetically pleasing to some, but wood roofing has a long list of disadvantages, including limited fire-, wind- and weathering-resistance. Effects of aging that cause splits, or curling in wood, also requires more maintenance than other roofing options. Cedar shake manufacturers have come up with a variety of treatment options to ease the natural limitations of wood, but these enhanced products can be costly.

Metal roofing is the most recent product to challenge asphalt shingles’ impressive market share. Metal roofs have respectable wind and fire resistance, but over time many may require additional coatings to maintain its original color, adding to the price. They initially cost about 30 percent more than high-end asphalt shingles—copper roofing can be twice as expensive—which can make them less than practical in today’s competitive steep-slope roofing market.

In uncertain economic times, installing an asphalt- based roof is a practical choice.  Spending considerably more money on a metal roof that can fade and rust over time may not provide a return on the initial investment.

Separating fact from fiction

There is no question that metal roofing has come a long way from the non-galvanized, corrugated tin roofs of the past. High-quality metal roofing made of aluminum or other light-weight materials and finished with Kynar/Hylar® or other specialized coatings can resist fading and chalking for decades.

However, these high-end metal roofs can’t compete with architectural, asphalt-based shingles when it comes to low initial life-cycle costs and reasonable installation fees.

In addition, exposed fasteners on lower cost metal systems lead to leaks and can be a maintenance expense. A lower hail protection rating may also be associated with metal roofing materials.

Many metal roof systems will also require coating over time to maintain their aesthetic charm that can be paramount in a residential environment. 

“Restoration of metal roofing is a target market for most coatings manufacturers,” said Lynn Picone, Sr. Product Manager for the Topcoat line of reflective coatings for GAF.   

John Ferraro, General Manager for the Roof Coatings Manufacturer Association confirmed the use of new technology reflective coatings as one option to restore metal roofing and also added that reflective coatings used in a myriad of restoration applications have grown over 40 percent in the past 5 years.

Unfortunately, it is the property owner who must pay the additional costs for these “extras.”

Any professional roofing contractor who installs both asphalt shingles and metal roofing will tell you that asphalt shingles are easier to install, repair and maintain. Asphalt shingles also feature a much broader selection of products and price ranges, as well as an increased availability of installers than metal roofing.

In northern climates, some metal roofing products also require snow guards to prevent the dangerous movement of ice and snow on a sloped roof. These accessories suspend the build-up of snow and ice until it can melt completely or drop off in small amounts. Again, this can complicate the roofing installation, may add additional costs, and could compromise the waterproofing integrity of the system if not installed properly.

Condensation forming under metal roofs is another concern in a variety of climates. The severity of the problem also varies based on construction type; location of vapor retarders, if any; lack of vented air space above ceilings and in attics; the levels of interior moisture being generated by the household; and, a variety of other factors.

Condensation forming under metal roofs is a concern, and the Metal Construction Association addresses it specifically in an August 2007 technical paper, “Controlling Condensation in Steep Slope Metal Roofing Systems.”2-7

The asphalt-based roofing industry has dealt with the issue of condensation under steep-slope roofs for decades. Asphalt shingle manufacturers recommend—and often require—sufficient levels of attic ventilation that can usually be achieved through a combination of ridge and soffit ventilation. However, these solutions are not always practical for metal roofing systems.

The proper installation of asphalt shingles is also well-documented in comparison to unconventional, custom metal roof designs. For example, in March 2011, the Asphalt Roofing Manufacturers Association (ARMA) and the National Roofing Contractors Association released Quality Control Guidelines for the Application of Asphalt Shingle Roof Systems.

This booklet provides guidance, based on technical knowledge from experienced asphalt shingle manufacturers and installers, for the on-site evaluation of asphalt shingle roof system applications. The booklet provides concise and standardized information, as well as visual examination evaluation criteria for a roof substrate surface, underlayment, drip edge, fasteners, asphalt shingles and flashings.

For more information about this guide, please visit www.asphaltroofing.org.

Protecting the environment

It is true that in today’s economy, some property owners are more interested in affordability than sustainability when it comes to steep-slope roofing.

However, more and more consumers are seeking “green” products in an effort to live as environmentally responsible as possible.

That’s why ARMA and the Construction Materials Recycling Association have spent years developing innovative solutions and breaking down barriers to enhance the sustainability of asphalt shingles.

When it is time to replace a roof and dispose of the old materials, contractors have more convenient, cost-effective options available to recycle and reduce waste. Recycled asphalt shingles provide valuable material such as asphalt and aggregate that can be used in road construction or maintenance projects.

Years ago, ARMA formed a sustainability committee to further research environmental issues, such as recycled content and shingle recycling. Many asphalt shingle roof systems contain recycled content and use significantly less energy during its manufacture than other types of roof systems, including metal roofing.

Typically, asphalt shingle production is more common place, strategically covering a wide geography—resulting in less energy used for transportation and installation. Shingles may be shipped in recyclable packaging, and many use locally available raw materials. In 2011, a record number of roofing contractors participated in shingle recycling programs across the U.S.  For more information, visit www.shinglerecycling.org or www.earth911.com.

Both many metal and asphalt shingle styles and colors also meet reflectivity standards for “cool” roof systems. But for shingles, the choices are greater.

Property owners can now choose from among a huge range of asphalt-based strip shingles, laminate shingles, interlocking shingles, and large individual shingles—across a dramatic spectrum of contemporary styles and shadow lines.

Perhaps most exciting of all is the enormous variety of rich, gorgeous colors now available, many of which are Energy Star® rated. Not to mention a profusion of textures, evoking the charm of natural materials such as tile, slate, and cedar without all of the cost and installation hassles.

There are many options in today’s steep-slope roofing market. But asphalt-based shingles offer an unparalleled combination of affordability, aesthetics, reliability and a wealth of choices for property owners.

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The Asphalt Roofing Manufacturers Association (ARMA) is a trade association representing the majority of North America's asphalt roofing manufacturing companies, plus their raw material suppliers. The association includes almost 95 percent of the nation's manufacturers of bituminous-based roofing products.

Footnotes

2. NRCA Metal Roofing Manual.

3. MBMA Metal Roofing Systems Design Manual.

4. ARMA Technical Bulletin – Ventilation and Moisture Control for Residential Roofing, 1997.

5. J.F. Straube, Moisture, Materials & Buildings, HPAC Engineering.

6. J.F. Straube, Moisture in Buildings, ASHRAE Journal, January 2002.

7. H. Hens and F. Vaes, Laboratory of Building Physics, Katholieke Unversiteit, Leuven, Belgium, The Influence of Air Leakage on the Condensation Behavior of Lightweight Roofs, Air Infiltration Review, Volume 6, No. 1, November 1984.