Technical Requirements for Building Consent Exempt Granny Flats
Building Consent Exemption Requirements for Granny Flats (DMRUs)
Granny flats do not require a building consent if the exemption criteria below are met.
You must apply for an Exemption Project Information Memorandum (PIM) before work begins. It is important to note that a key requirement of this process is that no building work has started before the exemption takes effect
All work must be completed by a Licensed Building Practitioner (LBP).
Single-Storey, Standalone and Self-Contained
A DMRU must be:
A new construction
Single-storey with no mezzanine
Standalone (detached)
Self-contained – complies with all the requirements of the Building Code that apply to the classified use of ‘Housing- detached dwelling’
Intended for a single household or family
Building Dimensions and Location
Floor area – 70m² or less
Maximum floor level - 1 metre above the supporting ground
Maximum building height - 4 metres above floor level
2 metres or more from other residential buildings or legal boundaries
Can not be built across boundaries between allotments
Construction Material Requirements
Construction material lightweight roof cladding materials, maximum weight 20kg per square metre
Wall cladding materials maximum weight 220kg per square metre
Light steel or timber framing
Water Supply System
Connection types:
Network utility operator (NUO)
On-site system (only if NUO is unavailable or lacks capacity)
Compliance pathways used (To be indicated by the LBP):
G12/AS1
G12/AS3
Surface Water Drainage System
Connection types:
NUO system
On-site system
Compliance pathway used (To be indicated by the LBP):
E1/AS1
E1/AS2
E1/VM1
Foul Water Drainage System
Connection types:
Connected to network utility operator (NUO) (eg reticulated sewer)
On-site system (used only if NUO is unavailable or lacks capacity)
Compliance pathway used (to be indicated by the LBP)
G13/AS1
G13/AS2
G13/AS3
G13/VM4
Additional Plumbing and Drainage Criteria
Total fixture units do not exceed 30
No pumped systems inside the building
Main drain is ≥ DN100 at minimum 1:60 grade
Branch drains are ≥ DN65 at minimum 1:40 grade
Upstream vents are ≥ DN65
No uncontrolled water heating
Electricity and Gas
Independent electricity supply
Independent gas supply (if applicable)
Electric or gas heaters if installed
Checklist
MBE have provided a handy checklist to ensure that all the actions required by the exemption have been carried out - Granny flats exemption: Completion checklist.
How We Can Help
In some situations, building consent or resource consent may still be required. If you need assistance interpreting the new standards or ensuring your proposal meets all requirements, our planning team is here to help.
We can provide expert guidance and support to ensure your granny flat project progresses smoothly.
