Granny flats foundations guidance

About this document

  • Published on 10 September 2026
  • ISBN: 978-1-997308-54-6 (Online)

Introduction

Use this guidance to choose suitable foundation solutions for granny flats built under the granny flats building consent exemption.

The guidance:

  • explains which foundation solutions are suitable for different ground conditions
  • helps you choose an appropriate foundation type
  • explains how foundation solutions comply with the New Zealand Building Code.

This guidance applies to granny flats that:

  • are standalone new builds
  • have a net floor area of 70 square metres or less
  • are built under the granny flats building consent exemption.

The foundation solutions in this guidance are optional. You can use other foundation solutions if they comply with the New Zealand Building Code.

Contents

The guidance includes:

  • the purpose of the guidance and who it is for
  • the policy and regulatory context for granny flats
  • ground conditions and foundation selection
  • foundation types and design considerations
  • glossary, test methods and example reports.

Disclaimer

This document is a guide only. It should not be used as a substitute for legislation or legal advice. To the extent permitted by law, the Ministry of Business, Innovation and Employment (MBIE) is not responsible for the results of any actions or omissions taken on the basis of information in this document, or for any errors or omissions.

Supporting resources

Visit the granny flats resources hub for videos and additional guidance about the granny flats exemption:

Building a granny flat: resources

 

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: