By the end of 1998 New Zealand had a suite of three Earth Building Standards. These were the first and most comprehensive of their kind in the world.
The standards development project was managed by Standards New Zealand (SNZ) supported by the members of a voluntary Technical Committee, each of whom had specialist knowledge in a relevant area. The Earth Building Association of New Zealand provided committee members with expertise in both the design and construction of earth buildings.
As well as many mandatory provisions, the standards have extensive commentary sections throughout which contain much in the way of advice and explanation which with help the design and construction of successful earth buildings.
The Earth Building Standards referred to are:
NZS 4297:1998 Engineering Design of Earth Buildings (Specific Design)
This provides for the structural and durability design of unfired earthen wall buildings. The scope is limited to adobe, pressed brick, poured earth and rammed earth and which contain clay and other aggregates, and which rely on the clay particles present to achieve satisfactory performance with or without chemical stabilization. Such materials shall comply with NZS 4298 “Materials and Workmanship for Earth Buildings”.
NZS 4298:1998 Incl Amendment#1 2000 Materials & Workmanship for Earth Buildings
This sets out requirements for the materials and workmanship requirements for the use of unfired earth in the form of adobe, pressed earth brick, rammed earth or poured earth. It applies to buildings which are designed in accordance with NZS 4297 “Engineering Design of Earth Buildings” and NZS 4299 “Earth Buildings Not Requiring Specific Design”. This Standard provides a means of compliance with the materials and workmanship requirements of earth walled structures. Test methods for earth building materials and criteria for acceptable results are included.
NZS 4299:1998 Incl Amendment#1 1999 Earth Buildings Not Requiring specific Designs
This sets down construction requirements for earth walled buildings not requiring specific engineering design. Many drawings of construction details which have been proved in New Zealand are included to help builders in earth to achieve durable and weather resistant buildings. It is to be used in conjunction with NZS 4298 “Materials and Workmanship for Earth Buildings”.
They are available from Standards New Zealand’s Web Site
These standards have been adopted as Acceptable Solutions to some clauses of the NZ Building Code. This means that any building designed and built in accordance with them automatically meets those provisions of the NZ Building Code and will get Building Consent.
Earth buildings must also meet other requirements of the building code. E2/AS2 is an Acceptable Solution for External Moisture http://www.building.govt.nz/userfiles/file/publications/building/compliance-documents/e2-external-moisture-dec-2011-6.pdf specifically written for earth buildings which now amends relevant parts of NZS 4299. Some other parts of the NZBC, such as H1 (Energy Efficiency), and some other referenced NZ Standards eg NZS 3604 for Light Timber Frame Construction have also been amended since the Earth Building Standards were written, so EBANZ Is currently embarked upon revisions of those parts of the standards in conjunction with SNZ .
It is possible to construct your earth house without the need for structural design by an engineer by using NZS 4299 Earth Buildings Not Requiring Specific Design. In fact the Standards will probably save you money anyway. It was reported recently that an engineer was able to complete some work for around $500 thanks to the standards, when it could have cost up to $3000 previously.
It is also crucial to the NZ Earth Building Industry that the Standards do not get photocopied. Every lost sale to Standards New Zealand means there is an increased chance that these Standards will not be revised and reviewed but simply dropped (SNZ is not government funded).