In 1976 ZINCALUME steel was released and quickly became the preferred choice for steel roofs. This steel is made of iron dipped in a special blend of aluminium, zinc and a little silicon and possessed higher corrosion resistance under aerated non-moist conditions.
Since late 2013, a next generation of ZINCALUME steel can be purchased with magnesium added into this mix. This newer steel technology results in even higher levels of protection against corrosion.
To compare warranties, previous generation ZINCALUME steel (labelled AZ150) carries a roofing warranty up to 25 years, whereas ‘Next Generation’ ZINCALUME steel (labelled AM125) carries a warranty up to 36 years.
Rainwater tanks made from ZINCALUME steel include AQUAPLATE® steel which is fabricated with an inner poly lining, but they can also be found made out of ZINCALUME steel with a separate polyethylene lining that sits inside to protect the steel from water corrosion.