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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 v24.03:Revision-History; V2403-March-2024

19.1 v24.03 – March 2024 

In the most recent update to the NZ Metal Roof and Wall Cladding Code of Practice , published on 1 March 2024, there were no substantial changes to recommendations.

New Clauses:

7.4.1 Wall Cladding End Laps: Giving guidance for flashing end laps on wall cladding. Including an illustration.

Editing and rearrangement:


The rest of the updates consisted of some renamed clauses, and minor corrections and edits.

19.1A Revision Detail v24.03 - 2024 - March

CategoryClause Number (prior to update)Clause (As of current publication)Details
2 - Editing and rearrangement11 IntroductionUpdated Revisions Message
2 - Editing and rearrangement2.12.1 DefinitionsAdded definition for Stand-off clips.
1 - Minor Errata3. Material GradeFixed typo in title for 3.4.5C Typical Result for G550 Steel.
2 - Editing and rearrangement4.174.17 Tray Roofing Clip DurabilityMade provision for plastic clips in table 4.17A Allowable Clip Material for Tray and Trough Cladding Over Dry Internal Environments.
2 - Editing and rearrangement5. Gutter Capacity CalculatorUpdate Manufacturer's Data illustration to ignore freeboard when there is Overflow along Gutter
4 - Clause Inserted 7.4.1 Wall Cladding End LapsNew Clause giving guidance about wall cladding end laps.
1 - Minor Errata8.48.4 Flashing CoverSized text for consistency throughout the illustrations. Added a hem to 8.4E Barge Flashing Cover — Trapezoidal and Secret Fixed and 8.4G Barge Flashing Cover — Corrugate. Adjusted the cover shown in 8.4O Parapet Cap Cover (no change to values)
2 - Editing and rearrangement8. Parapet CappingsNew illustration showing a 8.5.4G Parapet-Roof Intersection.
2 - Editing and rearrangement12.1.312.1.3 Thermal NoiseRenamed photograph to 12.1.3A Poor Purlin-to-Rafter Connection.
1 - Minor Errata14.1114.11 OverhangMinor adjustments on illustration for improved accuracy, some minor content editing for clarity.
1 - Minor Errata15.4.515.4.5 Tray FixingsTypo fix.
1 - Minor Errata15.4.815.4.8 Tray VentilationTypo Fix.
1 - Minor Errata15.4.1115.4.11 Tray Roof FlashingReformatted text in illustrations for consistency.
4 - Clause Inserted 19.1 v24.03 – March 2024New revison clause detailing changes following the update on 1 March 2024