According to Coventry Fasteners , roofing fasteners have been a weak link in building structures. The problem does not lie in any design or performance of the fasteners, but their failure occurring as a result of a weakening overtime caused by corrosion.
Corrosion is normally associated with non-precious metals such as steel, zinc, aluminium and copper and is the natural process of reverting the metal to the ore from which it came. In the presence of air, water or salt, these metals corrode rapidly. The presence of oxygen causes oxides to form, which gives the metals a disfigured appearance and causes them to be unsafe or useless.
Corrosion of fasteners can be caused by salt laden air from the ocean, airborne acids from industry and chemical sprays, UV from the sun or humidity in tropical and moist areas. Corrosion affects the performance of fasteners which can cause structural integrity issues. To combat the forming of corrosion on fasteners it is important to understand the areas which are most prone to corrosive elements and then react by selecting the most appropriate fastener type and coating for the application.
Class 3 is recommended for external use in mild or moderate industrial and mild marine applications. In moderate marine applications, Buildex recommend ZACS 4 or Climaseal 4 corrosion protection. Buildex coating Climaseal 3 complies with this class.
Class 4 is recommended for external use in moderate and severe marine environments, classified in accordance with ISO 9223 as generally between 100m from the beach front to approximately 300m inland. In high winds, this may extend further inland. Buildex coating ZACS 4 and Climaseal 4 comply with this class.
When fixing polycarbonate, stainless steel and aluminium roofing profiles in highly corrosive environments, it is recommended that stainless steel fasteners should be used.
In order to test the actual corrosion performance of their products, Buildex operate a research, development and testing programme. Buildex started the use of ‘real world’ outdoor exposed testing, operating three outdoor testing stations and have recently utilised four sites controlled by BHP and CSIRO.
Outdoor test sites expose the fasteners to corrosive influences. Anti-corrosive coatings on Buildex fasteners such as Climaseal 3, ZACS 4 and Climaseal 4 meet and exceed AS3566. Product features such as Shankguard are a result of the research, development and testing programme.