Titanium – zinc is the most commonly chosen roofing sheet. Manufacturers’ warranty covers up to 30 years, but you can expect longer life. Assuming that the sheet loses its thickness of 2 microns/year, after 100 years a sheet with a thickness of 0.7 mm becomes 0.4 mm thick.
Titanium – zinc sheet consists of (in accordance with DIN EN 988):
99.685 % zinc (zinc with a purity of at least 99.995 %)
copper 0,08-1,0 %
titanium 0.02-0.2 %
aluminum 0-0,015 %
On the market there are different colors available, which are always a derivative of gray. The smallest thickness of the metal sheet that is used for roof covering is 0.7 mm, for elevation 0.7 mm thickness is allowed but for visual reasons of 0.8 mm is recommended .
Titanium – zinc sheet is available in glossy natural silver color (so-called bright-rolled). After a few days application in normal weather conditions the sheet naturally starts becoming matt and takes on patina (first covers with zinc hydroxide and then zinc carbonate, which prevents from further corrosion). You can also get a titanium-zinc sheet artificially patinated in various shades of gray. These sheets maintain the factory color regardless of the weather.
The advantages of titanium – zinc:
- good press formability sheet – around 7 mm in an Erichsen attempt
The disadvantages of titanium – zinc:
- cracking during bending at a temperature below 6 degrees centigrade (with some color sheets even higher)
- the need to separate the sheet from the basis with structural mat (vapour permeable underlay), that provides the ability to drain the condensate on the bottom side of the sheet
- high thermal expansion coefficient in the direction of rolling (2.2 mm/m with an amplitudeof 100 degrees centigrade).