With regard to Option 1 I would have thought that for any form of dual occupancy council approval is essential and it is the council approval that will take time. So even if a Private Certifier approves that the building is fire rated and done properly as a dual ocx (which can take a week or so...
I have recently purchased a property in hills area that has 4 bedrooms.
The good thing about this property is that the previous owner has built and approved extension on the house with it's own separate entry from the side of the house a huge bedroom and it's own bathroom and shower plus a...