Loading ...Roofs. Our Colorbond sheets don’t rust where they are cut or drilled, and I’ve often wondered about that. So I looked it up. Thanks for the prompting!
“BlueScope Steel recommend ‘cold cutting’ coated steel products. If this recommendation is followed, these products will ‘self heal’, that is, the zinc in the surrounding coating will protect the newly exposed edge. How does this happen? In the presence of moisture, a reaction occurs between the zinc and the steel which results in galvanic protection of the exposed steel, thereby inhibiting corrosion. The degree of protection depends on the thickness of the coating (the amount of zinc), and this is taken into account when Building Standards are formulated.”
They have standard coatings, and two heavier duty ones for seaside locations. I have been on hundreds of Bluescope roofs and never seen any rust.
Railway. Looking at the sleepers in the photo makes me wonder what condition the bridge timbers are like. Stopping off to admire the view might induce severe anxiety!