Sleep outs are not granny flats – part two 

Part two of this BRANZ bulletin explains the Schedule 1 exemptions for sleepouts, including what’s allowed, the conditions that apply and when building or resource consent may still be required 

Sleepouts are often treated as a simple, consent-free alternative to small dwellings – but the distinction is more restrictive than many builders and homeowners realise. 

Under Schedule 1 of the Building Act, sleepouts can be built without consent only if they meet specific conditions. For example, to be build without a consent, they must not include kitchens and sanitary facilities. 

That means they are not interchangeable with small stand-alone dwellings, commonly referred to as granny flats, which operate under a separate exemption framework. 

Sleepouts up to 10m2 

The exemption for sleepouts up to 10m² has the fewest specific conditions around its construction. There is no minimum setback to the legal boundary and any residential building in the exemption for sleepouts up to 10m².  

While there are no minimum setbacks in this particular exemption, there are other requirements that may affect this. These may include district/unitary plan rules such as those around daylight recession planes and requirements in Building Code clause C regarding the risk of fire spreading to other property.  

Sleepouts are covered by Acceptable Solution C/AS1. Where an external wall is less than 1m from the boundary, the wall facing the boundary must have a fire resistance rating (FRR) of 30/30/30. (The three numbers in the FRR represent time to failure in minutes for how long the element can retain its loadbearing capacity, how long it can maintain its fire-separation capability and how long the element can shield heat from its far side. See Build 180 for more details.) This requirement does not apply if an automatic sprinkler system is installed. If the sleepout is less than 2m away from the main home on the same property (measured from the cladding) or less than 2m from a home on a neighbouring property, the sleepout wall will also need a 30/30/30 FRR. 

Sleepouts 10-30 m2 built with lightweight materials 

Of the three exemptions allowing sleepouts of up to 30m², this option allows homeowners to carry out the largest amount of the design and construction work themselves.  

The term ‘lightweight materials’ means:  

• Only light timber framing or light steel framing can be used.  

• Only lightweight wall and roof cladding materials can be used.  

Light wall claddings include:  

• Weatherboards – timber, fibre-cement or PVC.  

• Panel cladding – fibre-cement sheet, plywood and other panel materials.  

• Sheet metal claddings.  

Light roof claddings include: 

• Profiled sheet metal (typically a steel alloy).  

• Metal tiles.  

• Asphalt or fibreglass/asphalt shingles (usually fixed over plywood sarking).  

• Membranes on plywood substrates (but be aware that membrane suppliers usually require their products to be installed by trained and approved applicators).  

The technical definitions can be found in NZS 3604:2011 Timber-framed buildings. The wall cladding cannot weigh more than 30kg/m² and the roofing cannot weigh more than 20kg/m². To find out more about the weight of building materials to see if they are suitable, ask a building material supplier or check the manufacturer’s documentation.  

Several options for light wall cladding and light roof cladding are covered in Acceptable Solutions E2/AS1 (for timber-framed construction) and E2/AS4 (for light steel framed construction). Ensure that you are referring to the most recent edition of these Acceptable Solutions.  

The structural components of the sleepout must be designed and built so that they comply with Acceptable Solution B1/AS1. For timber-framed buildings, this can be achieved in practice by following NZS 3604:2011. For light steel framing, see the National Association of Steel Framed Housing design standards.  

If the intended building work involves extending an existing single-storey detached building, the total net floor area cannot exceed 30m².  

The foundations can be concrete slab on ground or a timber suspended floor following NZS 3604:2011.  

For all sleepouts 10–30m², the minimum setback to the legal boundary and any residential building in the Schedule 1 exemption is 1m. Note that, in practice, a greater setback or fire-rated walls may be necessary to comply with other requirements as discussed in 3.2.2 and 3.2.3. 

Kitset/prefab sleepouts 10–30m² designed/reviewed by an engineer 

The product manufacturer or supplier must have had the design of the building carried out or reviewed by a chartered professional engineer. The responsibilities of the manufacturer are covered in section 14G of the Building Act. 

The manufacturer or supplier should provide to the building owner/purchaser written evidence that a chartered professional engineer has designed or reviewed the building. It is important to follow the instructions of the manufacturer/supplier with regards to any building work required. 

Sleepouts 10–30m² designed/supervised by an LBP 

Any design or construction work for a sleepout under this exemption must be carried out or supervised by an LBP: 

• The design can be carried out by an LBP with a design licence or by a registered architect. 

• The construction work should be carried out or supervised by an LBP holding a licence for that specific area of work such as foundations, carpentry, roofing and so on. 

The work involved in this exemption is not restricted building work because building consent is not required. LBPs do not have to supply a record of work but are still professionally accountable for the work. The oversight of the Building Practitioners Board still applies. 

Building code and other Building Act requirements 

Sleepouts must comply with the Building Code to the extent required by the Building Act. Because a sleepout is a habitable space, it must have, among other things, fresh air ventilation, natural lighting, thermal insulation, a safe escape path and a smoke alarm. Understanding these requirements before design or construction starts is essential. 

While documents such as Acceptable Solutions and referenced standards can be used to show how a building may be constructed to comply with the Building Code, the documents may contain limitations or requirements that mean a sleepout as planned cannot be built. For example, NZS 3604:2011 has limits around subfloor members (pile lengths, for example), which may mean that a sleepout cannot be built on very steeply sloping land unless extensive excavations are made (and excavations come with their own rules and potentially a need for resource consent). 

For residential building work of $30,000 (including GST) or over, including a sleepout, there must be a written contract.