A small standalone dwelling still needs a foundation suited to its site. MBIE published new granny-flat foundation guidance in September 2026 for qualifying homes built under the building consent exemption. It gives owners, designers and builders a way to think through ground conditions and foundation options. For a Northland property, that conversation is worth having before a standard plan, kitset or fixed price becomes the starting point. [1]
What the new foundation guide actually covers
MBIE's guidance applies to new standalone dwellings with a net floor area of no more than 70 square metres that are being built under the granny-flat building consent exemption. It explains how ground conditions affect foundation selection and how a proposed solution can meet the Building Code. The foundation solutions it describes are optional, not a list of compulsory designs for every section. Another solution may be used if it complies with the Code. [1]
That matters when someone brings a standard floor plan to a section in Whangarei, Kaipara or the Far North. A drawing that works well on one site does not establish what lies beneath the next one. Talk with the designer and builder about what property records, site observations and ground investigation are needed before committing to the foundation design. Where conditions are uncertain, ask whether a suitably qualified geotechnical or structural professional should assess them.
Choose the foundation for the site, not the site for a foundation shown in a sales brochure.
Look below the proposed floor level
Start with the location and level of the proposed dwelling. Check access for construction, the fall of the land, evidence of fill or persistent wet areas, existing retaining work and where rainwater will go. These are prompts for investigation, not a remote diagnosis of whether any particular Northland section is suitable. MBIE's new guide is specifically intended to help match foundation solutions with different ground conditions. [1]
A ground assessment can affect the floor height, excavations, drainage design, build sequence and budget. If a concept relies on extensive cut and fill or a retaining wall, price that work separately rather than assuming it comes with the small dwelling. Ask the project team to record the ground assumptions in the design and quote so changes discovered during site works can be discussed clearly.
Check what the PIM says about the site
The building consent exemption does not mean the council is absent. For a qualifying project in Whangarei District, the owner must apply for a project information memorandum (PIM) and notify the council before work begins and after completion. Whangarei District Council says its review considers the exemption criteria, site hazards, infrastructure, heritage, bylaws and district plan requirements. Work can begin after the PIM is received and all conditions are met. The PIM may instead identify a need for a building consent. [3][4]
The council also says it does not approve, monitor or inspect the exempt construction itself. That makes the design, licensed professionals, site records and quality checks especially important. Owners in Kaipara or the Far North should confirm the process with their own district council rather than assume Whangarei's forms and steps apply unchanged. [3][4]
Keep foundations and services in the same conversation
Foundation planning should not stop at the edge of the floor. Locate existing water, wastewater and stormwater arrangements and find out whether there is capacity for another dwelling. A new foundation location can affect the route for drainage and services; an assumed connection can in turn affect where the dwelling sits. MBIE's general exemption guidance points owners to site-specific risks, utility connections and other approvals. [3]
Further changes to the granny-flat exemption are scheduled for 8 October 2026, two days after this article's publication. MBIE says the changes will allow some existing network water and drainage connections to be used or modified where the utility provider agrees and any required approvals are obtained. Existing on-site systems may also be used or upgraded where they have enough capacity and meet the Building Code. As at 6 October, those changes are announced but not yet in effect. Check the operative guidance and the relevant utility provider's position before fixing a servicing plan. [2]
What to ask before accepting a foundation price
Ask what ground information the price assumes, who checks it and what happens if the investigation finds different conditions. Confirm whether excavation, ground improvement, retaining, drainage, access and spoil removal are included or separate. Ask the designer how the foundation choice fits the proposed dwelling and what drawings or calculations the builder will use.
Do not treat an image, an indicative package price or another property's foundation detail as an engineering assessment. MBIE's guide supports selecting a suitable solution; it does not remove the obligation for a compliant design and competent work. Under the exemption, all conditions still need to be met, the building must comply with the Building Code and the relevant work must be carried out or supervised by licensed building professionals. [1][3]
A practical Northland starting sequence
First, confirm the proposed dwelling qualifies for the exemption and obtain the relevant property and site information. Next, ask the design team what investigation is appropriate for the intended building position. Then review the PIM and any site-specific council information alongside the proposed foundation and servicing layout. Finally, request a quote that states its assumptions and the process for dealing with changes.
If you need the broader rules before tackling the ground, read our earlier granny-flat exemption overview. This article is general planning information, not an assessment of a particular section or a conclusion that any foundation type, exemption or service connection is approved. Check the current official guidance, council requirements and your site's details with suitably qualified professionals before work starts.
