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Earth buildings standards update laying path for new building designs

Drafts of three earth building standards are now available for public comment: DZ 4298 Materials and construction for earth buildings, DZ 4299 Earth buildings not requiring specific engineering design and DZ 4297 Engineering design of earth buildings.

Earth layers

What NZS 4298 is about

NZS 4298:2020 Materials and construction for earth buildings sets out requirements for the use of unfired earth in the form of adobe, cob, pressed earth brick, rammed earth, and poured earth. It applies to buildings that are designed in accordance with NZS 4297 or NZS 4299.

Commentary to this standard takes heed of the long history of successful earth building worldwide. It is necessary to demonstrate that earthen materials used (with or without admixtures) produce results that meet at least the minimum standards of strength and durability. Tests and the required results are detailed so that assurance can be given that the earth building material will meet NZBC requirements.

What NZS 4297 is about

NZS 4297:2020 Engineering design of earth buildings is intended for use by structural engineers. Many of the structural design principles are chosen to be similar to those for reinforced masonry and reinforced concrete, and it is assumed that users of this standard will have a knowledge of design in these materials. However, earth has unique characteristics that need to be considered apart from other forms of masonry.

What NZS 4299 is about

NZS 4299 Earth buildings not requiring specific engineering design sets a minimum standard for the design and construction of earth buildings. When applied by architects, designers, builders, engineers, apprentices, building consent authorities, and building industry regulators, NZS 4299 provides these users with cost-effective and practical specifications and guidance information for designing and constructing earth buildings, without the need for specific engineering design.

NZS 4299 provides prescribed methods for the design and construction of reinforced earth walled buildings including domestic dwellings and other residential buildings, and some commercial buildings that fit into 1.1 Scope and 1.2 Limitations.

A note from Graeme North, chair of the committee

After this standard was published in 2020, MBIE/Building System Performance (BSP) undertook to assess it for citation as Acceptable Solutions to some clauses of the New Zealand Building Code. After some consideration they identified a few parts of the published standard that they considered were not yet in a form that they could readily cite.

Some earth building standards committee members also noticed a few errors of a typographical nature that had crept in, and some users of the standards also reported a few details that could be a little clearer. Earth Building Association of New Zealand (EBANZ) also noted that some few minor areas of the published standards could benefit from minor technical updates in light of changing regulations and the results of new research.

MBIE/BSP (the building regulator) along with Standards New Zealand and the reconvened standards committee agreed to work together to look at the areas that might benefit from being amended.

After an exhaustive process these proposed amendments are now issued for public comment before being finally processed and incorporated into the 2020 Standard.

As chair of the standards committee I would like to thank my colleagues and everyone else who has assisted with this process in a collaborative and co-operative way to bring all this work to a satisfactory conclusion.
Our end goal is to make the use of a wide range of earthen materials as easy as possible in the context of Aotearoa/New Zealand and beyond.

To see the draft, learn more about the major changes for each and provide comments visit our Consultation hub:

Standards New Zealand consultation hub(external link)