Vertical brick cracks exterior chimney

[Randall Clark]

This home is approximately 28 years old and has three chimneys. All of them have thin vertical cracks, some wider than others. Any thoughts on causes of these cracks and repair process, if needed.

[Marc M]

This home is approximately 28 years old and has three chimneys. All of them have thin vertical cracks, some wider than others. Any thoughts on causes of these cracks and repair process, if needed.
While inn Dale Febs class I remember he mentioned that these types of cracks are typically caused by expansion and contraction from heat. You can always try contacting hem directly. Hes a good guy.