Phone: 02 94817443

Can I build a 2 storey Granny Flat?

Can I build a 2 storey Granny Flat?

Generally, the answer is YES.

HOWEVER- the code stipulates that the higher the building gets, the larger the rear and side setbacks will need to be, to compensate for the increased height. Once a building exceeds 3.8m in height, then a formula applies to determine the required setbacks, as per the table below.

Lot Size (sqm) Min Side Setback Amended Side
Setback Formula
Min Rear Setback Amended
Max Rear Setback
Height <= 3.8m Height >3.8m Height <=3.8m  Height >3.8m
450-900 0.9m 0.9m + (0.25 + H/3.8m) 3m 8m max
900-1500 1.5m 1.5m + (0.25 + H/3.8m) 5m 12m
1500+ 2.5m 2.5m + (0.25 + H/3.8m) 10m 15m

H= Additional Height Over the 3.8m


Block Size is 650sqm. Granny Flat Height is 4m from natural ground at the highest point. We know that the height of the building is 200mm higher than the 3.8m, therefore the following formulas will apply:

Side Setback Formula:  900mm + 0.25x200mm = 900mm + 50mm  = 950mm side setback

Rear Setback Formula:  3000mm + 3x200mm = 3000mm + 600mm = 3600mm rear setback

NOTE: once the building reached 5.5m or higher (up to 8.5m), the rear setback can remain at 8m



Ph: (02) 9481 7443

Or visit our SHOWROOM at:

Unit 20, 7 Sefton Road, THORNLEIGH NSW 2120