The changes in AS 1684.2-2021 from the 2010 edition are outlined briefly in the Preface to the new edition - see below. You will also find a summary of the changes in an issue of TimberTrader News which you can access via this link https://www.timbertradernews.com/2020/08/19/standard-changes/.

Exposed timber with conventional coatings only achieves Group 3 status. However, it's possible that a case can be made for CLT 'massive construction' combined with fire retardant treatment to achieve Group 2 status via a Performance Solution. More detailed advice on using this pathway is contained in our Technical Design Guide #17 titled Fire Safe Design of Timber Structures - Compliance with the NCC. A copy can be downloaded free of charge from our website via this link https://www.woodsolutions.com.au/publications.