Is zinc the new green standard for building?
article from HowStuffWorks.com
A bird's-eye view of Paris shines with the natural patina of zinc. In the late 1800s, zinc was the material of choice for Parisian rooftops. Once metallurgists honed the process of smelting zinc into sheets, the metal became popular particularly in Belgium, France and Germany [source: Porter]. Two hundred years later, some of those original roofs still crown the historic buildings.
Borrowing from this dated European trend, American architects and contractors seeking more sustainable resources have rediscovered the value of zinc for roofs and walls. Embedded in the Earth's crust, a majority of the element comes from underground mining. Extracting zinc along with other metals and minerals for manufacturing takes a toll on the environment. But compared to aluminum, copper and steel, zinc requires a fraction of the energy to convert it into usable materials.
Zinc is the 27th most common naturally occurring element, frequently found in batteries, brass and galvanized steel. Our bodies depend on zinc for cell production, vision and fertility. When we catch a cold, zinc supplements can give our immune systems a boost. Although saddled with a higher price point than other building materials, including asphalt shingles and timber, zinc is providing fresh options and inspiration for healthier home construction as well.
Gray metallic paneling may not sound appealing for home sweet home, but zinc has some surprising -- and attractive -- benefits. Zinc sheeting is highly malleable, which means it can conform to a variety of styles, both angular and curved. The shapes of the individual zinc panels are manufactured in any number of shapes, such as undulating waves, interlocking hexagons and parallel ridges. After time, its brighter gray coloration gives way to a duller patina that can be tinted with hues of blue, green and red.
The Benefits of Zinc Sheeting
We hear a lot these days about going green inside the home. But what about the greenhouse gases produced from the construction and maintenance of the buildings we reside in? Timber converted to wood paneling, noxious chemicals in paints and the alteration of natural landscapes comprise only a few of the negative environmental impacts of new construction. For the green-conscious home hunters, zinc's properties can ease this aspect of eco-guilt.
Architectural grade zinc sheeting is a mix of zinc, copper and titanium to maximize malleability and tensile strength, or the maximum weight it can support. Overall, the innate resilience of zinc is one of its most important assets. A properly installed zinc roof can last beyond 100 years, compared to 25 years for asphalt shingles. Zinc owes this impressive longevity to its ability to heal itself. If you leave a piece of iron out in the rain or in contact with salt, the chemical reaction will form ferrous oxide, or rust, which corrodes the iron. Zinc, on the other hand, develops a protective layer called zinc hydroxyl-carbonate [source: Zaso]. Once formed, that layer blocks moisture and chemicals from penetrating to the zinc beneath; if scratched, the hydroxyl-carbonate will reform over time.
The low toxicity of zinc sheeting is a major plus for the environment. Every year, more than 10 million tons (9 million metric tons) of asphalt shingles alone end up in landfills [source: Northeast Recycling Council]. Toxic chemicals in the shingles then leach into the soil. Conversely, zinc is nearly 100 percent recyclable. In addition, the water run-off from zinc roofing doesn't pick up additional chemicals that will taint the soil and groundwater supply.
Since most zinc sheeting can be recycled, it further lowers the energy cost of manufacturing. Already, zinc mining and production take a quarter of the energy needed for aluminum and half that for copper [source: Zaso]. Moreover, recycling zinc demands less than 20 percent of the original input [source: Evans].
Probably the most pertinent downside for the average consumer is cost. Zinc roofing and siding cost more than the average brick and mortar on the market, similar to the price of copper [source: Lengel]. In the long run, zinc's durability and low maintenance may outweigh the initial price difference. And until U.S. cities' skylines share the zinc-speckled sheen of Paris, be prepared to pay a significant premium.
- Evans, Layne. "Architectural Zinc: From Gray to Green." McGraw Hill - Provided by RHEINZINK America, Inc. Construction.http://ce.construction.com/article.php?L=102&C=377&P=1
- Lengel, Allan. "Hip Lofts to Bring Glimmer of Zinc to Hyattsville." The Washington Post. April 9, 2007. (April 6, 2009)http://www.washingtonpost.com/wp-dyn/content/article/2007/04/08/AR2007040800904.html
- Northeast Recycling Council. "Asphalt Shingles Waste Management in the Northeast." February 2007. (April 6, 2009)http://www.nerc.org/documents/asphalt.pdf
- Porter, Frank. "Zinc handbook." International Zinc Research Organization. CRC Press. 1991. (April 6, 2009)http://books.google.com/books?id=laACw9i0D_wC
- Zaso, Janet. "Essential Zinc: Building for the Future." McGraw Hill Construction. April 2009. (April 6, 2009)http://continuingeducation.construction.com/article.php?L=84&C=487&P=1