Survey confirms life expectancy of 40+ years without major maintenance
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After 26 years, the drip edge of this roof in a heavy industrial environment shows how the coating continues to prevent the spread of red rust. |
55% Al-Zn is a metallic coated steel created to give exceptionally long life in new and retro-fit roof applications. A major survey of European roof applications now confirms superior performance from roofs in UNPAINTED 55% Al-Zn, and shows a life expectancy in excess of 40 years without the need for major maintenance.
A random selection of roofs in UNPAINTED 55% Al-Zn was subjected to close visual inspection. Roofs tested were mainly in urban, industrial and marine environments, and ranged in age from 9 to 26 years. Most (some 80%) had a slope of 10 degrees or less. Buildings in Germany, France, Belgium and the Netherlands were surveyed in 2003, following a 2002 inspection of roofs in the UK and Sweden.
Summary of findings
- The superior corrosion resistance of unpainted 55% Al-Zn
is proved beyond doubt. Components and accessories in ‘traditional’
galvanised steel were in most cases suffering from advanced deterioration,
whilst 55% Al-Zn remained virtually unaffected.
- All roofs were in good to excellent condition in terms
of both technical and aesthetic performance - regardless of age, location
or environment.
- Based on the field inspection results, all are projected
to perform well for at least another 20 years without the need for major
maintenance. This indicates a total life of 40+ years, and confirms
the experience of similar surveys in Australasia and North America.
- In some cases, small isolated areas of corrosion were
observed. These were attributable to manufacturing defects, poor installation,
unsatisfactory design or maintenance practices, or localised highly
corrosive environments in the vicinity of chimneys or roof vents.
- Environmental conditions play a vital role in the long-term
performance of unpainted 55% Al-Zn roofs, because a highly corrosive
environment depletes the protective metallic coating. Environmentally-friendly
regulation has caused emissions of airborne acidifying pollutants and
the incidence of acid rain to be substantially reduced throughout Europe.
This means that the long-term performance of 55% Al-Zn roofs will increase
yet further; and expectations of life in excess of 50 years may well
become the norm.
- Quality of design, installation and maintenance is vital to obtain full benefit from the exceptional corrosion resistance and long life offered by 55% Al-Zn. The survey underlines the strong recommendation for designers and installers to select ancillary fittings and fasteners in materials compatible with 55% Al-Zn. For more details, click here.