Copper is the best metal sheet in roofing. Its durability is almost not limited by natural weather conditions and in rural atmosphere corrosion occurs of less than 0.2 mm for 100 years. Roofing and facade uses a copper sheet with a thickness of about 0.6 mm.
Copper sheet is available most commonly in the natural copper- gold color, as the time passes it covers itself with brown and then green coating. It is patina consists primarily of copper hydroxy carbonate which protects the plate from further corrosion. You can also get artificially patinated copper plates in various shades of brown and green (mostly using ammonium sulfate). Some of them will change color over time, others remain permanently in the factory color.
Advantages of copper :
- low thermal expansion coefficient in the direction of rolling (1.7 mm/m with an amplitude of 100 degrees centigrade)
- the possibility of bending at low and high temperatures
- forge ability best of all sheets
Disadvantages of copper:
- in contact with other metals (mainly steel) galvanic corrosion occurs at the contact with another metal
- in contact with the wall or facade green stains may appear