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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:Revision-History; 2022-April

19.9 2022 – April 

The following revisions to the NZ Metal Roof and Wall Cladding Code of Practice were published on 1 April 2022.

Change in recommendation:

4.9.1 Dissimilar Metals: Gutters and spouting made from materials which are incompatible with the roof cladding to include special provisions such as a gap between spouting and fascia, using leaf deflectors, and considering low fronted spouting.

Revised clauses:

  • 8.4 Flashing Cover: Revision of the minimum requirements for flashing cover in the Metal Roofing Code of Practice. Drawings have been updated and a category C added for SED Wind Zones up to 60 m/s on all pitches.
  • 10.10 Ventilation Pathways has completely revised for clarity. The revision includes a new recommendation to provide additional ventilation for trough or tray section roofs.

The rest of the updates consisted of minor changes, editing, and new drawings for 14 Installation, without any changes in recommendations.

19.9A Revision Detail - 2022 - April

CategoryClause Number (at time of update)Clause (As of current publication)Details
3 - Substantial change to recommendation4.9.1, Dissimilar MetalsChange of recommendation for spouting and roof cladding made from incompatible material.
3 - Substantial change to recommendation8.38.4 Flashing CoverClause has been completely revised.
3 - Substantial change to recommendation10.110.10 Ventilation PathwaysClause revised for clarity.
2 - Editing and rearrangement11 IntroductionUpdate Revisions Message
1 - Minor Errata2.1, 2.12.1 DefinitionsAdded defintion for SED Wind Zone.
2 - Editing and rearrangement3.15, 3.133.4 ProfilesInserted new Drawing: Profile Types –
2 - Editing and rearrangement5. Gutter Capacity CalculatorEnabled Profile Description Field to describe product.
1 - Minor Errata5. Valley Capacity CalculatorStandardise internal structure - no user facing or operational changes.
1 - Minor Errata5. Downpipe Capacity CalculatorStandardise internal structure - no user facing or operational changes.
2 - Editing and rearrangement5. Maximum Area Above Spreader CalculatorEnabled Profile Description Field to describe product.
2 - Editing and rearrangement7. Maximum Run CalculatorEnabled Profile Description Field to describe product.
2 - Editing and rearrangement8. Flashing EdgesCopy moved from 8.4 Flashing Cover to this clause.
4 - Clause Inserted 8.4.1 Apron UpstandsNew clause created from 8.4 Flashing Cover.
4 - Clause Inserted 8.4.2 ClearancesNew clause created from 8.4 Flashing Cover.
4 - Clause Inserted 8.4.3 Ridging and Other Transverse FlashingsNew clause created from 8.4 Flashing Cover.
1 - Minor Errata8. Eaves FlashingCorrected reference typo E1/AS1 to E2/AS1.
2 - Editing and rearrangement9. Maximum Area Above Penetration CalculatorEnabled Profile Description Field to describe product.
1 - Minor Errata10. Fascia VentsGrammar fix.
4 - Clause Inserted Vented Soft EdgeNew clause.
2 - Editing and rearrangement10. Methods of VentilationClause renamed.
1 - Minor Errata10. BattensGrammatical fix for clarity.
4 - Clause Inserted 10.10.3 Applied FleecesNew Clause.
2 - Editing and rearrangement14. ScrewsUpdated drawings: 14.13.2D Screw Gauge and 14.13.2E Threads per Inch (TPI).
2 - Editing and rearrangement14.1614.16 Stop-endsDrawings updated: 14.16A Dog-eared Stop-ends, 14.16B Pull-up Stopends, and 14.16C Corrugate Stop-ends.
2 - Editing and rearrangement14.1714.17 Turndowns (Drip Forming or Drip Edging) UPdated drawing: 14.17A Profile Turndown
2 - Editing and rearrangement14. Roof Cladding DamageDrawing updated: 14.19.1A Sealed and Riveted Saddle
2 - Editing and rearrangement14. UnloadingDrawing updated: 14.3.1A Sling with Spreader Bar.
2 - Editing and rearrangement14.614.6 Walking On RoofsDrawings updated: 14.6A Walking in the Pan and 14.6B Spreading Weight over two Ribs.
4 - Clause Inserted 19.9 2022 – AprilRevision message – April 2022.