This section looks at how the height requirements may impact the construction of your granny flat.

Building height:

(also referred as ‘height of building’) means the vertical distance between ground level (existing) and the highest point of the building, including plant and lift overruns, but excluding communication devices, antennae, satellite dishes, masts, flagpoles, chimneys, flues and the like. (Definition from Standard Instrument.)


  • The maximum height that can be achieved as complying development for a secondary dwelling is 8.5 metres measured from the ground below that point.
  • However, if the height of the secondary dwelling is more than 3.8 metres then the setback will increase relative to both the height of the building and size of the lot.


Note: the above image illustrates a rare situation where the granny flat is built above the garage however the same rules apply if the granny flat was built to the side of the garage fronting the primary road.

  • A setback is to be calculated at the closest point to the boundary from the building line. (In determining the building line, the eaves of the building are excluded if they are less than 450mm from the boundary.)
  • The front setback of any building should be consistent with the existing streetscape. That is, the building must have a similar setback as the two closest buildings (within 40 metres).



  • If a lot is a battle-axe lot with three boundaries, disregarding any access laneway, the rear setbacks are not used. The side setbacks apply to these three boundaries.
  • Identifying the rear and side boundaries on a corner lot requires you to identify the primary road. The primary road is the road that faces the front of a principal dwelling house.
  • For the purposes of calculating a side or rear setback, the maximum building height of a dwelling on a sloping lot is to be used.