Hi,
I am thinking about building a small room (3mx6m) with ensuite inside the rear gable end of my garage. From what I understand this means a change of use from class 10 to class 1 in the BCA.

My situation is I have a 6mx9m garage seperate from the house, built 5 years ago, it is colourbond with a portal frame. The slab has a membrane under it. I would like to install a room and ensute into the rear of the garage, basically a bedsit for my daughter.

After talking to the council, state building control and the surveyor who signed off on the garage. I think I need to:



  • engage a building designer to draw the site plan and interior fit out,
  • pay a building surveyor to assess whether the slab and structure meet the building code,
  • have an engineer assess the structural detail,
  • pay a council fee for a building permit, then I can,
  • hire a builder, a plumber and an electrician.


This seems like a lot of consultants for some battens, insulation and gyprock.


Whilst I recognise the need for the sparky and the plumber, do I really need a builder to screw some battens to the top hats and attach some gyprock?


Are there likely to be other hurdles I haven't for seen, will the slab be suitable for a class 1? It is 100mm MP25 with a 200mm thick edge, there are 400x400x400mm footings under each post for the protal frame.

Another complication is that the garage is too close tot he fence for a Class 1 building, it is 800mm and needs to be 900mm, although I am not certain the fence is straight and in the right position. Does this mean I will need a fire rated wall on that side?

Fortunately for me I did put thermal break between the roof sheeting and the top hats, plus sisalation inside the wall cladding.

What I can do without needing to change the use of the building? Can I build a room for use as a studio that has a bathroom for convience? (not intended to be slept in of course)



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