Fitting Ridge tiles

[Coaster]

Hello.
I have hardro slates with ridge tiles re-fitted or replaced in places by a roofer. The ridge tiles are ok, but where the cement they're sitting on has cracked in certain places... the crack has followed on into the roof tile below.
Can I ask if that's normal?
If i ever attempt repairs, is there any methods to stop the cement cracking the tiles below (that is if it's important)

ta for any comments.

 

[HaydnExport]

no it's not, get the roofer back to do a proper job

 

[datarebal]

These dont last forever.. I have seen jobs where many have cracks in them they are man made and not natural slate. How old is the roof?
It might be that there were hair line cracks in them when the ridges were rebeded.. with all the movement during rebeding might not have helped things.

Probably the best course of action would be to totally replace the top course then rebed the ridge.

 

[Coaster]

The tiles are about 40 years old, they were re-seated about 2 years ago.

 

[datarebal]

probably living on borrowed time then.