If it’s the walls of the building that are affected, then it’s the responsibility of the strata.
The drainage pipes are the responsibility if the strata and they need to maintain them in good order.
As for the garden brick walls, if they are in your lot the damage and repair may be payable by the strata. There was a case through the courts in nsw where bamboo grew into neighbours yard and caused damage. The court determined the owner of the bamboo was responsible for the repair.