Renovation Sub-floor Area (Logan)

Hi

I am planning to renovate the sub-floor area (not legal height) of a highset home in Logan. Do I need to get the construction in the sub-floor approved and certified by council? My plan is:

1. Convert the double garage to two study/home office with one rumpus
   
   
2. Add several windows to the wall
   
   
3. Replace garage doors
   
   
4. Add a bathroom
   
   
5. Add a kitchenette

Another question is generally how much does it cost for this kind of renovation?

 

I have done a few now in Logan, the first I did mostly myself with a few basic tradies for 20k, though I'm pretty hardcore

Not sure about papers and permits, but someone will be along soon to talk you out if it and no doubt start fear mongering the thread with insurance floods leases blah blah blah

Pick the right property in a good location for these projects and the returns are substantial, also buyers are paying a premium ATM for these, so the cg is sweet, though you probably already know this.

I have been watching these seq build underneath highset threads on here and to be honest, you will find better advice off here from people that are doing/done it.