Rusty red roof
On this example, after nearly nine years, the coating is coming to the end of its life, thereby requiring a new coating.
|Rusty red roof requiring recoating|
The coating has reached the end of its effectiveness because the coating no longer can stretch as the metal panels expand. Splits have developed allowing sunlight to directly interact with the primer. When primer is affected by sunlight, the metal becomes exposed, meaning rust will show.
Darker colors age faster when compared to light tints.
In this case new primer is needed. Ideally, the time to recoat is before the primer is compromised.