Posted September 6th, 2013 by Lenora Hamilton
When it comes to durable roofing materials, metal is hard to beat. Although steel roofing is currently the most popular metal roofing product used in the United States, zinc roofing has many benefits over steel. Zinc roofing is has been common in Europe since the 19th century, and this popularity is slowly being transferred to the United States for both commercial and residential applications. Longevity, durability and malleability are just a few of the many unique characteristics of zinc roofing that make it an excellent roofing choice.
Zinc has several distinct advantages over steel when it comes to resisting corrosion. Steel roofing is usually galvanized or aluminized, meaning zinc and aluminum coatings are used to protect the material against natural oxidation. Additional coatings, often containing color, can further protect the material against the elements. However, over time the coating breaks down and can become damaged, which can leave the steel substrate exposed and unprotected. The iron in steel reacts with oxygen and moisture, creating iron oxide, also known as rust. Rust is unsightly at best and will eventually lead to the destruction of the roof.
Zinc also reacts with compounds in the atmosphere, but instead of combining with oxygen to form a destructive oxide, zinc reacts with carbon dioxide, which results in zinc carbonate. Unlike rust, zinc carbonate does not compromise the structural integrity of the zinc panel but instead forms a protective, bluish-gray patina over the surface. Zinc’s property of forming a protective patina has been recognized and utilized for hundreds of years. Galvanizing is the process of applying a thin film of zinc to another surface, usually iron or steel, to prevent rusting. Zinc roofing goes a step further than galvanizing and uses panels completely manufactured from inert, non-corroding zinc.
Durability and Long Life
Because zinc is naturally resistant to corrosion and also stands up better to sun, wind and rain, a zinc roof has a much longer expected lifespan than a standing seam steel roof. While most steel roofs have an expected life of 25 to 50 years, properly installed zinc roofing can last over a century without failing. Zinc roofing is also recyclable at the end of its life.
Metal roofing in general is an excellent choice due to the ease of installation and long useful life. Zinc roofing possesses these properties along with the added benefit of being extremely flexible. Zinc can be easily bent into shapes ranging from gradual curves to sharp angles. Because of this unique characteristic, zinc is an excellent choice of material for use in modern architecture and on structures with uniquely shaped rooflines.
Zinc roofing does not use hazardous chemicals during manufacturing and does not require treatment or sealing prior to installation. This means that the runoff from a zinc roof is free of dangerous chemicals and makes a zinc roof an ideal addition to a green building that employs a rainwater collection system. The water collected from a zinc roof can be used to irrigate a lawn or garden with no risk of introducing chemicals that can damage grass, harm fruits and vegetables or contaminate groundwater.
Zinc roofing may seem cutting edge and new, but it has in fact been used as a roofing material for nearly 200 years. The popularity of zinc roofing during that time has fluctuated with the availability of zinc and with existing tastes and construction trends. Zinc roofing is a premium material, compared to steel or aluminum roofing systems. However, when considering all of the benefits, including corrosion resistant properties, long life and adaptability to a variety of roof shapes and configurations, it is still an excellent choice for use on all types of buildings despite the additional initial financial outlay.