When two different or “dissimilar” metals are interconnected or joined, rust in the form of galvanic corrosion will occur. Galvanic corrosion can have serious consequences as it can accelerate the process of corrosion for one of the metals involved.
The best way to prevent rust via galvanic corrosion is to avoid mixing metals and always use similar metals together. Think zinc-coated steel gutter mesh and zinc-coated steel screws with your steel roof and you’ve got the right idea.
The proportion of total time that surfaces are wet is known as “time of wetness” (TOW). Atmospheric corrosion occurs when metal surfaces are subjected to frequent wetting by dew, fog or rain, especially if the moisture has an acidic content. Gutters clogged with leaves and debris are bad news for corrosion prevention. Fortunately, clogged gutters can be easily avoided by installing an over-the-gutter mesh with the appropriate aperture (hole size) for your home and location.
Galvanised steel, COLORBOND® steel, zinc-coated steel and stainless steel are all examples of specially coated steels that are rust-resistant. However, it is important to choose a rust-resistant steel that is fit for purpose. Avoid mixing dissimilar metals by selecting the rust-resistant steel that is most compatible with your roof and gutter materials.
For further reading on Dissimilar Metals click here.
In and of itself, stainless steel is a rust-resistant material. However, when joined to a roof made from a different material, such as COLORBOND® steel, it can cause your roof to rust prematurely. If you are considering stainless steel, it is important to ensure that the roof and gutter materials are compatible and not dissimilar.