Granny flat rules in Whanganui.
A small home in Whanganui may provide accommodation for family members or a tenant on an established section. Some older properties offer space, but access, existing services and trees can affect the layout. Heritage and character requirements may apply in villa streets. Ground conditions vary from sandy terraces to papa clay, and low-lying land near the river needs flood information. The design needs to address the requirements of the actual property.
Building consent and resource consent requirements
The building consent exemption and the national planning standard are separate. A project can proceed without either consent only when all the relevant requirements are met.
Schedule 1A, under the Building Act 2004
Building consent, if all Schedule 1A conditions are met
A new, detached, single-storey home up to 70 m² may be built without a building consent if every exemption condition is met. Licensed professionals, Building Code compliance, a Project Information Memorandum and council notifications are still required.
NES-DMRU, under the Resource Management Act 1991
Resource consent, if all relevant requirements are met
The national planning standard can permit one detached minor dwelling without resource consent when its standards and other relevant requirements are met. Some district and regional rules remain, including those for hazards, infrastructure and earthworks.
Both took effect on 15 January 2026. They do not retrospectively approve existing dwellings.
National planning standards
The NES-DMRU is the national planning standard for detached minor dwellings. These measurements apply when its requirements are met. A district plan can allow more generous measurements. Other relevant site restrictions still apply.
| Standard | Residential zone | Rural zone |
|---|---|---|
| Maximum internal floor areaMeasured to the internal face of the external walls. An attached or internally accessed garage counts inside it. | 70 m² | 70 m² |
| Maximum area of the site covered by buildingsThe 50% standard overrides any district plan coverage standard below 50% in a residential zone. | 50% | As required by the zone |
| Minimum distance from the main homeDistances are measured from the outside face of the wall cladding. | 2 m | 2 m |
| Minimum distance from the front boundary | 2 m | 10 m |
| Minimum distance from side and rear boundaries | 2 m | 5 m |
The permitted activity rule: One detached minor residential unit per site. It applies in residential, rural, mixed use and Māori purpose zones, as defined in the National Planning Standards, or the equivalent zones where a council has not implemented them yet.
- Special character, design guides and visual amenity
- Screening for rubbish and recycling storage
- Wall and roof colour, reflectivity and external finishes
- Minimum outdoor open space, privacy or sunlight access
- Minimum window area
- Parking
- Minimum site size
- A design that satisfies a local character guide
- A minimum private outdoor space around the unit
- A sunlight or privacy assessment for the neighbours
- An on-site car park
- A minimum site area under the district plan
- Neighbour notification for a permitted activity
Other requirements for your property
Check heritage and character requirements for older properties, including any limits affecting visibility and materials. Flood information matters on low-lying land near the river. Existing drainage and service connections may need upgrading. The ground report, available space and construction access also need to inform the proposed design.
Flooding, coastal hazards, fault lines and land stability can affect the building location, floor level and need for consent. Check the council information and obtain site advice where needed.
Check connection requirements and capacity. Relevant regional plan rules still apply, including requirements for an on-site wastewater system.
Buildings near electricity lines and other significant infrastructure must meet the relevant safe-distance and planning requirements.
Rules can apply near airports, ports, industry and farming operations, or on contaminated land. They may affect where a home can be built and what design measures are needed.
Earthworks may need resource consent even when the dwelling does not. Subdivision requirements are separate and remain in place.
Relevant protections for heritage, cultural sites and outstanding natural features still apply.
Check covenants and easements on your property title. The national planning standard does not override private covenants, and more stringent council bylaws can still apply.
Development and financial contributions may be payable. Ask your council to confirm which charges apply to your project.
A district plan may allow a larger home or a smaller boundary setback. That does not change the separate Schedule 1A requirements. For example, an 80 m² dwelling or a 1 m setback would not meet the 70 m² and 2 m conditions for this building consent exemption.
Check the main eligibility conditions
Check these conditions with your designer and council. They are a starting point; all relevant exemption requirements must be met.
The minor dwelling must be physically separate from the principal home. An attached extension is assessed under different requirements.
The NES-DMRU planning standard requires a minor dwelling to be secondary to a principal home on the same site and in the same ownership. If both are proposed together, confirm the construction order and requirements with the council.
The NES-DMRU allows one detached minor dwelling per site. For a cross-lease, the site includes all the land under the cross-lease. A district plan may allow more, subject to its requirements.
The building consent exemption applies to new dwellings. A building conversion may meet the planning standard, but it is not covered by this building consent exemption.
Ground, climate and construction
Sandy terraces and papa clay require foundations based on the ground report. Drainage upgrades and access can affect work on older properties. The indicative construction period is 9 to 12 weeks, with the chosen builder confirming the actual scope and programme.
Steps to plan your project
Review the title, planning requirements and services with your designer, builder and council before construction.
Check covenants and easements that could restrict a second home, its size, location or access.
Review council maps and relevant district and regional rules for natural hazards, infrastructure and other restrictions.
Identify the water, wastewater and stormwater connections and confirm capacity. Check any requirements for an on-site wastewater system.
Apply for and receive a Project Information Memorandum before construction starts. It records the council information relevant to the property and proposed work.
Your designer confirms the design requirements for the property and prepares the required plans and documentation. The Schedule 1A exemption requires appropriately licensed professionals.
Notify the council before construction and provide the required completion documents afterwards. Your designer and builder must supply the records and certificates required for their work.
Frequently asked questions
Do heritage overlays stop backyard builds in the villa suburbs?+
Heritage or character requirements may affect visibility, materials and other design decisions. A dwelling behind an existing house can have different effects from street-facing work, but the actual rules still need to be checked for the property and proposal.
What rent could a two-bedroom home receive in Whanganui?+
Around $520 a week is an indicative rent used on this site. Actual rent depends on the property's location and condition. Compare current listings with the full project cost, including foundation and drainage work, and allow for vacancy and ongoing expenses.
Sand or papa: does the ground matter?+
The ground conditions affect foundation design. Sandy terraces may suit slabs, while papa clay may need engineered footings and particular drainage. The ground report should establish the requirements, with the resulting construction work included in the chosen builder's quote.
Can an older villa section accommodate a small home?+
An older section may have enough space, but suitability depends on access, services, drainage, trees and applicable title or planning requirements. Heritage rules may also apply. The design needs to account for those conditions rather than relying on section size alone.
Official guidance
Use the official guidance below and confirm current district requirements with your council before construction.
- NES-DMRU: Frequently Asked QuestionsMinistry for Cities, Environment, Regions and Transport, September 2026 (INFO 1387)
- National Environmental Standards for Detached Minor Residential UnitsMinistry for the Environment
- Granny flats exemption guidance and resourcesBuilding Performance, MBIE
- Changes to allow granny flats to be built without a building consentBuilding Performance, MBIE
Checked against these sources in September 2026. Confirm the current requirements for your property before construction.
More information for Manawatū-Whanganui
Regional guidance and nearby council guides.