KINGI® roofing screw is the responsible professional’s choice
A well-constructed sheet metal roof should easily last more than 50 years. However, problems are often caused by rusting roofing screws whose corrosion resistance is not sufficient for outdoor use, even though according to building regulations a roofing screw must resist rust for as long as the roofing sheet.
HAMK’s Sheet Metal Centre tested the corrosion resistance of roofing screws from eight different manufacturers in urban and industrial climate conditions. The test included Kingi’s C4-approved roofing screw compared with CE-marked screws that had been on the market longer.
In Finland, the most common atmospheric corrosivity category is C3, urban and industrial atmosphere, which covers approximately 80% of buildings. In the test, the roofing screws were exposed to cyclic salt spray that best imitated these climate conditions. The test duration was set at a demanding 1,000 hours. The screws were fastened to Ruukki’s Pural roofing sheet, which has known weather resistance and made it possible to determine a comparison period for the corrosion resistance of the screws.
CE-marked screws do not withstand outdoor exposure
Both the screw’s base material and coating affect the corrosion resistance of a roofing screw. The first CE-marked screws began to rust at the head after just 187 hours of salt spray exposure. The coating on many CE-marked roofing screws was completely ruined after 425 hours of exposure.
After 618 hours, all but one of the screws had lost their paint and were covered in rust, and their testing could no longer be continued. After the 1,000-hour test, only KINGI® roofing screws were fully usable. Only KINGI® roofing screw is C4-approved.
After the 1,000-hour test, only the KINGI® roofing screw was completely rust-free. At the end of the test, rust had formed on the cut edges of the Pural roofing sheet. Practical experience shows that edge corrosion of a similar extent develops on the Pural coating only after well over 20 years of use. The test duration can be considered the extreme service life of a good roofing sheet. According to the test, the KINGI® roofing screw lasts well for the service life of the roofing sheet and even longer.
Developed and manufactured in Finland, the KINGI® roofing screw is the only painted carbon steel screw approved for use in severe urban and industrial climates, that is, in corrosivity category C4.
With the exception of Kingi, all the screws in the test, including the CE-marked ones, were ruined after 618 hours.
KINGI® self-drilling screws after 1000 hours of exposure.