So that’s why the roof’s colour changed.Ĭopper is also a desirable roofing material due to its pliability, which makes it easier to work with and bend into the different shapes needed for the roof. The City of Toronto began replacing the copper roof on Old City Hall in 1997 and the new copper has not yet acquired its patina, which can take many years to form, depending on the climate. It’s a big reason why copper roofs are so durable. In its natural, untreated form, copper sheets will react with the atmosphere to form a green patina, often referred to as antique copper or Verdigris. The tarnish is called patina and very often it protects the material below to help it last longer. The result is a compound called malachite (Equation 4), which varies in color from shades of dark green to shades of blue. The difference in colour from the green of the old roof to the brown of the new roof are due to a tarnish that forms over time on copper, many other metals, stone and stained and finished wood. The first reaction that gives patina its color is when one molecule of carbon dioxide and one molecule of water, both in the air, react with two molecules of copper oxide on the surface of the copper. Installed in the late 1920s, Old City Hall’s roof was made of copper and the fact that it lasted about 70 years reinforces copper’s reputation as one of the most durable roofing materials. Like on any “home”, the roof needed replacement. What Happened to the Roof on Old City Hall? It was the same colour as the domed roof on another Toronto landmark, St, Lawrence Hall and the same colour as many world landmarks, including the Statue of Liberty.īut, starting in 1997, Old City Hall’s roof colour began to change and it was completely brown by 2005. Call VR Roofing for all of your copper roofing needs.If you live in or around Toronto, you may have wondered about the changing colour of the roof on one of the city’s most famous landmarks, the classic Old City Hall.įor as long as most people reading this post can remember, Old City Hall’s roof was a light green colour.

Van De Hey Refined Roofing, LLC (VR Roofing) is a custom roofing company that proudly services the Appleton, Little Chute and the Fox Valley area, Sheboygan, Oshkosh, Madison, Milwaukee, Shorewood, Sheboygan, Oconomowoc, Verona, Waukesha, Green Bay, and De Pere areas in Wisconsin. In closing, you can achieve your desired color of copper roof patina, but it is not as long lasting as the natural patinas ar e.

It will depend on the geographic characteristics as discussed above if you wish to maintain that chemically chosen patina. The copper roof starts out salmon pink brown and makes it’s way to the statue of liberty bright green.Īs I said before, you can alter the coppers color via chemical treatment but here’s the catch, unlike the natural progression of the color from salmon pink to bright green, when you do a chemical treatment to change the patina over the course of a few months, the processes will need to be repeated a certain amount of time later. There is, however, a major caveat to that unnatural choice.Ĭoppers natural patina occurs as a gradual progression depending on the coppers physical orientation and the local weather and pollution levels on a grading scale of lighter and lighter greens. It’s even possible to choose the color of a coppers patina through chemical treatment. That being said it is still possible to use chemical treatments to advance this copper roof patina process. The environment will affect the color and the rate at which the copper changes colors.

The thing about copper that a lot of people love is that its natural coloring is very sensitive to the air and certain elements of the air that are geographically relevant, as well as that areas humidity. To properly understand what’s involved in achieving a copper roof patina one must first understand copper.Ĭopper is an extremely durable and versatile metal that can last close to one hundred years and even after can be recycled and almost one hundred percent reused.

Patina copper roof