The Building Code of Australia (BCA) has evolved over several decades and buildings are only normally required to meet the standards of the version of the code that applied when their design was approved. 

However, the requirement to upgrade a building to current code can be triggered by undertaking significant works at that building. 

Compliance with all aspects of the BCA can be assessed, whether a general audit of the building, or investigation of a specific element (such as combustible cladding material).  Assessments can occur at any point in the ownership cycle but are particularly relevant around transactions or when considering major refurbishment work or upgrades.