Are your chimney stacks secure?
Chimney stacks are one of the most vulnerable elements of a building because of their high exposure. Unfortunately, they are usually in the most inaccessible places. It may be possible to examine them from the ground or from a neighbouring building with the aid of binoculars. If the stack is of brick or stone, examine the condition of the mortar pointing. If it is rendered, check for cracking in the coating. Check also that the pots are securely fixed.