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Disclaimer

Although the information contained in this Code has been obtained from sources believed to be reliable, New Zealand Metal Roofing Manufacturers Inc. makes no warranties or representations of any kind (express or implied) regarding the accuracy, adequacy, currency or completeness of the information, or that it is suitable for the intended use.

Compliance with this Code does not guarantee immunity from breach of any statutory requirements, the New Zealand Building Code or relevant Standards. The final responsibility for the correct design and specification rests with the designer and for its satisfactory execution with the contractor.

While most data have been compiled from case histories, trade experience and testing, small changes in the environment can produce marked differences in performance. The decision to use a particular material, and in what manner, is made at your own risk. The use of a particular material and method may, therefore, need to be modified to its intended end use and environment.

New Zealand Metal Roofing Manufacturers Inc., its directors, officers or employees shall not be responsible for any direct, indirect or special loss or damage arising from, as a consequence of, use of or reliance upon any information contained in this Code.

New Zealand Metal Roofing Manufacturers Inc. expressly disclaims any liability which is based on or arises out of the information or any errors, omissions or misstatements.

If reprinted, reproduced or used in any form, the New Zealand Metal Roofing Manufacturers Inc. (NZMRM) should be acknowledged as the source of information.

You should always refer to the current online Code of Practicefor the most recent updates on information contained in this Code.

Scope

This Code of Practice provides requirements, information and guidelines, to the Building Consent Authorities, the Building Certifier, Specifier, Designer, Licensed Building Practitioner, Trade Trainee, Installer and the end user on the design, installation, performance, and transportation of all metal roof and wall cladding used in New Zealand.

The calculations and the details contained in this Code of Practice provide a means of complying with the performance provisions of the NZBC and the requirements of the Health and Safety at Work Act 2015.

The scope of this document includes all buildings covered by NZS 3604, AS/NZS 1170 and those designed and built under specific engineering design.

It has been written and compiled from proven performance and cites a standard of acceptable practice agreed between manufacturers and roofing contractors.

The drawings and requirements contained in this Code illustrate acceptable trade practice, but recommended or better trade practice is also quoted as being a preferred alternative.

Because the environment and wind categories vary throughout New Zealand, acceptable trade practice must be altered accordingly; in severe environments and high wind design load categories, the requirements of the NZBC will only be met by using specific detailing as described in this Code.

The purpose of this Code of Practice is to present both Acceptable Trade Practice and Recommended Trade Practice, in a user-friendly format to ensure that the roof and wall cladding, flashings, drainage accessories, and fastenings will:

  • comply with the requirements of B1, B2, E1 E2 and E3 of the NZBC;
  • comply with the design loading requirements of AS/NZS 1170 and NZS 3604 and with AS/NZS 1562;
  • have and optimised lifespan; and
  • be weathertight.

COP v25.12:Introduction

View Whole Section for Introduction

The NZ Metal Roof and Wall Cladding Code of Practice (COP) is published by NZ Metal Roofing Manufacturers Inc. (MRM), to provide:

  • acceptable trade practice for fixing metal roofing, metal wall cladding, and accessories,
  • prescriptive detailing for designers, and
  • sets a benchmark for the standard of detailing and workmanship required over and above that required to comply with the NZBC.

The COP does not describe or dismiss alternative methods, which may need specific acceptance by the Building Consent Authorities.

It is published in accordance with current technology, materials, and building codes. The COP will be periodically updated to reflect changes in legislation and standards or improvements in technology and available materials.

The most current Code of Practice is available on the MRM website, www.metalroofing.org.nz/cop, as Code of Practice Online (MRM COP Version 25.12).

In the latest update (on 1 December 2025), we made few substantial changes to recommendations. Most of the revision consisted of editing and rearrangement for clarity, consistency, and accuracy. We have also linked all published Bulletins to the relevant content in the CoP.

Important changes

Editing and rearrangement

  • 15.1.2A Spring Curving Calculator has been updated and can now work from either height or desired radius to enable profile selection and calculate the total length of seal required.
  • We made some edits for clarity and added a reference to wall cladding to 17.1.3.2 Point Load Testing.
  • In 4.6.3 Material Selection, we changed materials endorsed as complying with AS/NZS 2728 coating types to align with the current product range.

For a detailed list of updates, please visit 19.1 v25.12 December 2025 in the Code of Practice.

Bulletins

Published bulletins are now linked to relevant content in the Code of Practice.

Six new bulletins are now available from Bulletins on the MRM Home page:

 

Important Notice:

In a move to help us better understand our audience and make the NZMRM Metal and Wall Roof Cladding Code of Practice even more useful and relevant, we are introducing an industry selector to the existing registration form. If your particular industry is not listed please select one that is closest.

Registration is important so everybody will be informed of important revisions which is done on a quarterly schedule. You will only receive four emails per year regarding our updates.

The data gathered stays anonymous and will never be shared with anyone outside the NZMRM.