Roofs installed as long ago as 1977 are forecast to deliver corrosion-beating performance for at least another 20 years - without major maintenance.

Age: 26 years
Slope: 10 degrees
Environment: Heavy industrial
Location: Flemalle, Belgium

Installed in 1977, the 55% Al-Zn roof in the centre of the picture is very dirty, but despite 26 years in a very aggressive environment is still in good condition.

A section of the 55% Al-Zn roof abuts on to another profiled section in pre-painted hot-dip galvanised steel, and is also bordered by unpainted hot-dip galvanised. If ever a picture were worth 1000 words, this is it: the superior performance of 55% Al-Zn is obvious.

Age: 20 years
Slope: 18 degrees
Environment: Urban
Location: Tomteboda, Sweden

Unpainted 55% Al-Zn steel has weathered the urban environment of Stockholm exceptionally well - with virtually no change in performance or appearance since it was last inspected 14 years ago.

Age: 23 years
Slope: < 5 degrees
Environment: Industrial
Location: Münster, Germany

This standing seam roof in 55% Al-Zn certainly doesn’t look its age. The slight staining is probably due to the chromate-based passivation system which was applied twenty years ago in the manufacture of 55% Al-Zn: today’s passivation systems are enhanced with acrylics to reduce staining and abrasive marking. The staining does not affect the long-term corrosion resistance of the material.

Age: 22 years
Slope: 7 degrees
Environment: Urban
Location: Chambéry, France

This roof is in excellent condition, though a few seams showed some rusting caused by installation damage.

Age: 22 years
Slope: < 5 degrees
Environment: Industrial
Location: Wisbech, U.K.

After 22 years service in an industrial (high levels of acidifying pollutants) environment in the UK, the galvanised roof vent is terminally rusted, but the roofing in 55% Al-Zn is still in excellent condition.