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Sustainable Design
The Ecological Benefits of Metal Roofing
Metal roofing has a long, successful history worldwide. It's proven track record
spans all types of projects-new construction and remodeling for commercial,
industrial, and residential buildings. With today's heightened interest in and
demand for ecologically sound building materials, metal roofing rises to the
top as the product of choice. The Metal Construction Association ardently supports
metal roofing's inclusion in all lists of environmentally friendly or "green"
roofing materials
The ecological benefits of metal roofing include:
Sustainability
Metal roofing's durability can virtually eliminate the need to use future raw
materials to produce roofing. Metal roofing is unaffected by the hot-cold/wet-dry
weather cycles that break down other materials. Other roofing materials, however,
are heavily affected by weather extremes. In addition, metal roofing is known
for its ability to hold up against other weather forces including windstorms,
hail, ice, and snow. No other roofing material has greater ability to withstand
a wider range of weather conditions than metal. There are many handmade metal
roofs still in existence that date back to the 1800s. Commercially produced
metal roofing systems have been available since about 1910; numerous profiles
and types have been produced since then, and there are examples of these roofs
across the country. While some metal roofs are quite lasting and durable, with
exposed metallic surfaces, modern technology also has introduced quality paint
systems that beautify metal roofing and are warranted for as long as 50 years.
Metal roofs can be repainted for additional life, if necessary. As America's
homes and other structures age, it is imperative that we choose long-term building
products; metal is the product of choice for sustainability.
Recycled content
As consumers, many of us are careful to collect our recyclable materials and
turn them in for collection. In reality, though, we are offered very few consumer
products where we can "close the loop" by purchasing products that
are high in recycled content. Metal roofing, however, offers that option to
consumers by allowing them to choose a significant building product on the basis
of its recycled content. Most metal roofs have recycled content ranging from
25% to 95%. This is in stark contrast to conventional roofing shingles, which
have much shorter lives and use oil-based products as their primary raw material.
The recycled content of metal roofing has been a compelling reason for several
state and local entities, such as solid waste districts and departments of natural
resources, to include metal roofing on their list of "green" and recycled
content products.
Recyclability
While metal roofing is known for its extremely long life, it does have the added
benefit of being 100% recyclable if it is ever removed in the future, perhaps
as part of a building renovation. Whereas other old roofing materials are disposed
of by the ton in landfills across the country each year, the steel, aluminum,
and copper used in metal roofing can be recycled in their entirety, potentially
even becoming another metal roof.
Low Weight
Depending on the product chosen, metal roofing has a weight that is 1/3 to as
little as 1/8 the weight of conventional roofing shingles! In comparison to
heavy tile and slate roofing, the weight of metal roofing is virtually miniscule.
This low weight serves several valuable purposes. First, it puts less weight
load on a structure. This helps extend the life of buildings and it also provides
invaluable protection against roof cave-in threat in the event of seismic activity.
However, with retrofit applications, many metal roofs can be installed over
the old roofing material. This prevents the need to remove the old roof and
fill up valuable landfill space. Each year, about 20 billion pounds of old composition
roofing shingles are dumped into U.S. landfills. Metal roofing is the way to
avoid this degradation of the environment. Additionally, metal's low weight
and high strength present an ideal way to cover and encapsulate existing asbestos
roofing shingles rather than create a health risk as a result of removing the
asbestos and putting it in a landfill. State EPA offices support this practice
of asbestos shingle encapsulation.
Product Safety
Metal roofing and the finishes used on it are inert, safe materials that do
not pose a health risk. Furthermore, metal roofing is noncombustible, which
provides additional fire protection for homes. Of course, one roofing material
that has turned out to be very dangerous is asbestos shingle roofing. Asbestos
was used extensively many years ago and now that we have realized the health
hazards it poses, we're spending many millions of dollars each year to get rid
of it. This worry does not exist with metal. Also, many consumers with chemical
sensitivities are turning to metal roofing and finding that it does have the
allergy problems associated with other roofing materials. Today's commercially
produced metal roofing systems are carefully tested on an ongoing basis for
performance, wind resistance, fire resistance, and hail resistance. They are
listed with various building codes and entities including Underwriters Laboratories;
International Congress of Building Officials; Dade County, Florida; Southern
Building Code Congress International; and others.
Energy Efficiency
Metal roofing is rapidly gaining acceptance as a very energy efficient material.
Property owners have reported energy savings of as high as 20% and even more
after installing metal roofing. The reflectivity and subsequent energy efficiency
of metal roofing has been confirmed in studies done by Florida Solar Energy
Center, Florida Power and Light, Oak Ridge National Laboratory, and other independent
organizations. Ongoing studies are being conducted to continually substantiate
and quantify the energy efficiency of metal roofing. Many available metal roofs
are being documented to meet Energy Star requirements. Prepainted metal roofing
can display solar reflectance of at least 65% and thermal emittance of 80%.
This can have a tremendous impact on energy usage by reducing air conditioning
costs and the smog and pollution that are created by the production of that
energy. Additionally, the low thermal mass of metal roofing means that it dissipates
heat very quickly once the sun goes behind a cloud or sets for the day. Other
roofing materials have greater thermal mass and will continue to radiate captured
heat into the structures beneath them even when the sun is not shining.
Conclusion
In light of the above benefits, the Metal Construction Association strongly
encourages metal roofing's consideration and inclusion on lists of "green"
building products. Many state "green" programs have already included
metal roofing products on their published lists. Roofing is a major component
of any structure, and it is a component where the product chosen can have a
dramatic effect on the building's life cycle and energy costs. Metal roofing's
many benefits, including sustainability, recycled content, recyclability, low
weight, and energy efficiency, far outweigh virtually all other roof systems
from an ecological standpoint.
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