Certain heating emissions can also affect coloration. Sulphur from wood-burning stoves, for instance, may cause zinc around a chimney to take on a slightly yellowish color.

When applying zinc to a wooden substrate, care must be exercised in the type of woods used. Avoid woods with a pH less than five. They can have a corrosive effect on zinc in the presence of humidity.

Plywood as a direct support must also be avoided. It can be composed of acidic wood species or may contain tanins or phenolic glues that will aggravate the risk of corrosion on the underside of the zinc.

In general, zinc is most vulnerable from its underside. To prevent corrosion, a well-ventilated airspace is required, along with a protective barrier to separate it from incompatible supports.

An interesting aspect of green building is application of new technology and the subsequent revival of long-overlooked materials. Roofing can be produced from a number of products, including block tin, ingot copper, antimony, sheet zinc, sheet iron and tin-plated carbon steel, a widely-used sheet metal roofing product.

In the 1990s, metallurgical research and field testing was done to develop an alloy with extremely high corrosion resistance.

The result is a zinc/tin roofing material which is oxygen-reactive and which surpassed 5,164 hours of salt spray-testing with no visible rust.

A formulated combination of zinc and tin makes new tin roofs long-lasting and gives them unique visual characteristics. Alloy roofs are naturally reflective. New, high-tech coatings make alloy roofs even more resistant to ultraviolet radiation.

Coated, or uncoated, alloy roofs are designed to weather naturally to a gray patina and can withstand even severe corrosive conditions in industrial, coastal and salt-water environments, Thomas says.

Sustainable roof designs can range from a traditional standing seam roof to a vertical wall, barrel applications, shingles or customized sections in flat or spherical shapes.