Sorry I will correct that! A house with 4 or more tenants now has to be registered to be a rooming house. With the local council that is.

Try GIO for insurance, we have our rooming house with them. Rooms with 4 or more tenants now have to be registered. Here is a link that might be helpful:
http://165.142.249.2/CA256902000FE154/Lookup/CAV_Publications_Rooming_Houses/$file/Rooming_House_Operators_Guide.pdf