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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.


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 v24.06:Testing-And-Mrm-Standards; Mrm-Pre-Painted-Coil-Standard-Performance-Requirements

17.4 MRM Pre-Painted Coil Standard – Performance Requirements 

Materials used by New Zealand Metal Roofing Manufacturers Inc. (MRM) members for the manufacture of roofing, cladding and accessories, for use on Residential, Commercial and Industrial buildings, shall comply with this standard.

17.4.1 Part1: ASNZS/2728:2013 

Compliance with the following sections of AS/NZS2728:2013 in their entirety is required. To be clear, if the following sections are interpreted as Informative in AS/NZS 2728:2013, they are considered Normative (i.e., must be complied with) in this NZMRM standard.

  • Material must comply with Sections 2.1 through to 2.9 inclusive, including subsections, and section 2.10.2, of AS/NZS 2728:2013, with reference to Section 1 Scope and General.
  •  AS/NZS 2728:2013 appendices A, C, D, E, F, G, H, I (Cyclic corrosion test only), M and O are all integral parts of this standard.

17.4.2 Part 2: Additional Criteria 

In addition to the requirements of Part 1, all prepainted materials must comply with the Hazardous Substances and New Organisms (HSNO) act 1996.

17.4.3 Commentary 

Section 1 of AS/NZS 2728:2013 includes clauses on Scope, Referenced Documents, Definitions, Safety, Product Finishes, and Surface Protection

Sections 2.1 through 2.9 of AS/NZS 2728:2013 cover performance requirements. Specifically: Appearance, Gloss, Dry Film Thickness, Impact Resistance, Adhesion, Scratch Resistance, Durability of Organic Film, and Humidity Resistance.

Section 2.10.2 of AS/NZS 2728:2013 is the Cyclic Corrosion test. Note the MRM standard does not include the 2.10.1 Salt Spray Test.

17.4.4 Appendices of AS/NZS 2728:2013 included as Normative in the MRM Standard 

A   Purchasing Guidelines – Gives additional information, specific requirements and fitness for purpose.

C   Atmospheric Environments – Categorises environments for determination of performance level requirements of clause 2.8.

D   Test Panels –  Specifies preparation of test samples for exposure testing.

E   Reverse Impact Testb –  Procedure required for testing impact resistance to the reverse side

F   T-Bend Adhesion Test – Procedure to be used for T bend adhesion

G   Ball Adhesion Test – Adhesion test procedure for laminate products.

H   Durability and Corrosion Resistance – Procedure for 4 year exposure test to determine resistance to UV exposure and marine environment. Note: Compliance with this test has been interpreted as being Informative in AS/NZS 2728:2013. This test procedure is required for demonstration of compliance with this MRM standard.

I     Accelerated Corrosion test –  Note the MRM standard only requires that the Cyclic corrosion test be carried out.

M   Safety Requirements –  Guidelines on safe applications of paint coatings

O   Colour Durability –  This four year Colour Durability Expectations is Normative in the MRM standard and Informative in AS/NZS 2728:2013.

17.4.5 Appendices of AS/NZS2728:2013 considered Informative in the MRM Standard: 

B   Demonstrating Compliance –  Statistical sampling and Product Certification.

J    Test Sites – Categorisation of specific test sites for testing

K   Advice on weathering performance – Loss of Gloss, Chalking, Checking, Colour Fade and Erosion.

L   Storage and Handling

17.4.6 Copyright Acknowledgement 

The referenced standard AS/NZS NZS 2728:2013 – Prefinished/prepainted sheet metal products for interior/exterior building applications – performance requirements is provided by Standards New Zealand under licence 001027. Please refer to the Standard for full details, available for purchase from