2.3. Single-storey detached buildings up to 30sqm in floor area with prefab or kitset components

Medium sized metal shed with no windows.

This exemption covers the construction of small buildings such as garden sheds, greenhouses, cabins or sleepouts greater than 10 square metres but less than 30 square metres.

Please note: The below exemption comes into force from 31 August 2020. You will still need a building consent if your project starts before this date.

This exemption covers the construction of small buildings such as garden sheds, greenhouses, cabins or sleepouts greater than 10 square metres but less than 30 square metres.

Before you begin, please read the notes for single-storey detached buildings.

If you are providing sleeping accommodation in such a building, note that the facilities (eg portable water) of an existing dwelling must be readily available and used for sanitation, and the building cannot include cooking facilities because of the risk of fire.

If you are purchasing a prefabricated or kitset building, you will need to check with the manufacturer or supplier that a chartered professional engineer has designed or reviewed the building. Homeowners must also seek and follow manufacturers/supplier instructions to ensure that the building work be carried out in accordance with that design.

The net floor area of a single storey, detached building is limited to a maximum of 30 square metres.

The net floor area in a building is measured to the inside of the enclosing walls or posts/columns.

Some suppliers and manufacturers of proprietary products have pre-engineered kitsets with a unified sign-off from a chartered professional engineer. These kitsets must be constructed in accordance with the instructions and the design approved by the engineer.

What is exempt

  1. The owners of a commercial property intend to construct a 30 square metre detached building to serve as a garage. The proposed building will be more than its own height away from the boundaries and it contains no potable water supply and no facilities for cooking or sanitation. The owners want to buy a pre-engineered kitset from a proprietary product supplier or manufacturer which has been signed off by a chartered professional engineer for design. The kitset is then installed by the property owner in accordance with the instruction manual.
  2. A 25 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. Plans and specifications associated with the kitsets and prefabs are signed off by a chartered professional engineer. Subsequently, the work is carried out in accordance with that design.

What needs consent

  1. A homeowner decides to build a sleepout with a net floor area of 31 square metres on a property that has a residential dwelling on it. This sleepout would require a building consent as its floor area is greater than 30 square metres.
  2. A homeowner decides to construct a greenhouse with a net floor area of 25 square metres on a property that has a residential dwelling on it. The prefabricated greenhouse is imported from overseas without design sign off from a chartered professional engineer. This greenhouse would require a building consent as the greenhouse was not designed or reviewed by a chartered professional engineer.
  3. A 25 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. Although the building designed by a chartered professional engineer, the building is not made of kitset or prefabricated products. The building will require a building consent because the structural components are not kitset or prefabricated products (exemption 3B (section 2.4) may apply if the work is carried out or supervised by a licensed building practitioner).

What the law says

43. Single-storey detached buildings exceeding 10, but not exceeding 30, square metres in floor area (where kitset or prefabricated)

1. Building work in connection with any detached building if—

(a). the building is a kitset or prefabricated building, and the product manufacturer or supplier has complied with subclause (3); and

(b). the building work is carried out in accordance with the design referred to in subclause (3); and

(c). the building—

(i). 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

(ii). exceeds 10 square metres in floor area, but does not exceed 30 square metres; and

(iii). does not contain sanitary facilities or facilities for the storage of potable water; and

(iv). does not include sleeping accommodation, unless the building is used in connection with a dwelling and does not contain any cooking facilities; and

(v). if it includes sleeping accommodation, has smoke alarms installed.

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.

3. The product manufacturer or supplier (as defined in section 14G) must have had the design of the building carried out or reviewed by a chartered professional engineer.

This information is published by the Ministry of Business, Innovation and Employment’s Chief Executive. It is a general guide only and, if used, does not relieve any person of the obligation to consider any matter to which the information relates according to the circumstances of the particular case. Expert advice may be required in specific circumstances. Where this information relates to assisting people: