Rust is a form of corrosion associated with iron and steel reacting in the presence of moisture and oxygen.
What this means at your property
An orange stain on a surface may originate from a nearby fastener or metal component. Removing the mark may improve appearance while leaving the moisture source or deteriorating component unchanged.
Does a rust stain establish structural damage?
No. The significance depends on the component and its condition. Ask the appropriate specialist to evaluate affected structural or safety-critical metal, and separate stain cleaning from any necessary component repair or replacement.