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.
Related HowStuffWorks Articles
- Evans, Layne. "Architectural Zinc: From Gray to Green." McGraw Hill 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