Do i need council approval for this building?

A 9 square metre sleepout is constructed in the backyard of a residential dwelling. It is more than its own height away from all boundaries and the associated residential dwelling, and does not contain cooking or sanitary
facilities, or a potable water supply.

Owners of a childcare centre intend to build a 10 square metres detached building to serve as a staff retreat area. The proposed building will be more than its own height away from the boundaries. It contains no potable water supply and no facilities for cooking or sanitation.

Schedule 1 of the Building Act 2004

Single-storey detached buildings not exceeding 10 square metres in floor area

1. Building work in connection with any detached building that:
(a). is not more than 1 storey (being a floor level of up to 1 metre above the supporting ground and a height of up to 3.5 metres above the floor
level); and
(b). does not exceed 10 square metres in floor area; and
(c). does not contain sanitary facilities or facilities for the storage of potable water; and
(d). does not include sleeping accommodation, unless the building is used in connection with a dwelling and does not contain any cooking facilities.

2. However, subclause (1) does not include building work in connection with a building that is closer than the measure of its own height to any residential building or to any legal boundary.

Comparable materials and assembly are to be used; also replacement should be in the same position as the original.

Buildings that are not going to be lived in such as garages, sheds, farm buildings and potting sheds, can be repaired or replaced. But must not be a public building and can only be a single story.

Check with your local council on this as some council have the discretion to exempt quite detailed structures.

This could be a construction site office.

Make sure you always check that there are no planning requirements for your area (for example daylight planes, and how far you need to be from boundaries. Also sometimes you have rules for maximum coverage of an area).