This is an excerpt from NSW State Environmental Planning Policy (Exempt and Complying Development Codes) 2008 (Current version for 25 October 2019), Part 2 > Division > Subdivision 9. Full document can be found here.
Subdivision 9 Cabanas, cubby houses, ferneries, garden sheds, gazebos and greenhouses
2.17 Specified development
The construction or installation of a cabana, cubby house, fernery, garden shed, gazebo or greenhouse is development specified for this code if it is not constructed or installed on or in a heritage item or a draft heritage item, on land in a foreshore area or in an environmentally sensitive area.
2.18 Development standards
(1) The standards specified for that development are that the development must:
(b) not have a floor area of more than:
(i) on land in Zone RU1, RU2, RU3, RU4, RU6 or R5—50m², or
(ii) on land in any other zone—20m², and
(c) be not higher than 3m above ground level (existing), and
(d) be located at a distance from each lot boundary of at least:
(i) for development carried out in Zone RU1, RU2, RU3, RU4, RU6 or R5—5m, or
(ii) for development carried out in any other zone—900mm, and
(e) if it is not on land in Zone RU1, RU2, RU3, RU4 or RU6—be located behind the building line of any road frontage,
(f) not be a shipping container, and
(g) be constructed or installed so that roofwater is disposed of without causing a nuisance to adjoining owners, and
(h) to the extent it is comprised of metal components—be constructed of low reflective, factory pre-coloured
materials if it is located on land in a residential zone, and
(i) if it is located on bush fire prone land and is less than 5m from a dwelling—be constructed of non-combustible
(j) if it is constructed or installed in a heritage conservation area or a draft heritage conservation area—be located in the rear yard, and
(k) if it is located adjacent to another building—be located so that it does not interfere with the entry to, or exit from,
or the fire safety measures contained within, that building, and
(l) be a Class 10 building and not be habitable, and
(m) be located at least 1m from any registered easement.
(2) There must not be more than 2 developments per lot.