Residential space as private office space - Upgrade floors?

[Tomfh]

I have a job in which a residential building is being converted to private office usage, including a training class room. The existing floor joists satisfy residential live loading (1.5/2.0kPa), but struggle to satisfy commercial live loading (minimum 3kPa).

Is there any way to avoid upgrading floors in such situations? Maximum occupancy signage perhaps?

I am in Australia. Loading is AS1170 etc.

 

[To Madeira]

Don't forget the 2.7kN point load requirement in AS1170 as well.