When is shire approval needed?

From shire to shire (whether it be suburban and/or rural) regulations for retaining height does slightly vary, but in general, when retaining anything higher than 500mm will require shire approval and an engineer’s certificate.

What type of blocks/stone is better?

It is a personal choice. When built correctly natural, reconstituted or Natural earth blocks are a fantastic way to add value to your property. They are the most cost effective way to retain when comparing to brick or twin side which are also commonly used.