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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 v24.12:Revision-History; V2406-June-2024

19.3 v24.06 June 2024 

The updates published on 1 June 2024 include improvements to 5.4.2.3 Spouting Support Systems and clarifying recommendations to prevent negative pressure with 10.10.1.3 Ridge Vents. Substantial changes include removing wind load/span graphs for 0.70 mm aluminium.

Editing and rearrangement updates involve updating and editing images for consistency, clarifying 7.3.2 Roof Cladding Expansion Provisions, material thickness, and amending references to the availability of 4.16.1.6 AM Coatings in New Zealand. Minor edits were made for grammar, style, clarity, and consistency.

Notable revisions:

In addition to these and some minor edits and rearrangements, several images have been revised for consistency. For a detailed list of revisions, please visit 19.3 v24.06 June 2024.

19.3A Revision Detail v24.06 - 2024 - June

CategoryClause Number (prior to update)Clause (As of current publication)Details
3 - Substantial change to recommendation5.4.2.35.4.2.3 Spouting Support SystemsClause renamed. Expanded recommendation for compatibility of spouting support systems.
3 - Substantial change to recommendation10.10.1.310.10.1.3 Ridge VentsAdded recommendation for ridge vents to be smaller than eaves vents.
0 - Clause Removed3.11.2.3Trapezoidal Five Rib Aluminium – 0.70The clause has been removed because aluminium is now offered in 0.90mm as the standard thickness.
0 - Clause Removed3.11.2.1Corrugated Aluminium – 0.70The clause has been removed because aluminium is now offered in 0.90mm as the standard thickness.
2 - Editing and rearrangement11 IntroductionUpdated Revisions Message and rewriting for clarity. No changes in recommendations.
1 - Minor Errata1.41.4 AcknowledgementsTypo fix: tradespeople
1 - Minor Errata1.5.11.5.1 MediationMinor revisions for grammar and clarity. No change to recommendations.
1 - Minor Errata1.5.21.5.2 AdjudicationMinor revision for grammar, style, and clarity. No change to recommendations.
1 - Minor Errata1.5.31.5.3 Arbitration and LitigationMinor punctuation fix.
2 - Editing and rearrangement2.12.1 DefinitionsAdded definition for Vented Ridging.
1 - Minor Errata33 StructureMinor revision for style, grammar, and clarity. No change to recommendations.
1 - Minor Errata3.23.2 StandardsMinor review for style, grammar, and clarity. No change to recommendations.
1 - Minor Errata3.2.13.2.1 AS/AZS 1170.2:2011Minor revision for style, grammar and clarity. No changes to recommendations.
1 - Minor Errata3.33.3 PerformanceMinor revision for style, grammar, and clarity. No changes to recommendations.
2 - Editing and rearrangement3.4.63.4.6 Material ThicknessMinor review for style, grammar, and clarity. Edit to clarify the use of 0.63 mm material.
1 - Minor Errata4.24.2 Metal CorrosionMinor edit for style, grammar, and clarity. No change to recommendations.
1 - Minor Errata4.5.24.5.2 Sea SprayMinor revision for style, grammar, and clarity. No changes to recommendations.
1 - Minor Errata4.6.14.6.1 Assessment of Marine EnvironmentsMinor revision for style, grammar, and clarity. No changes to recommendations.
1 - Minor Errata4.6.24.6.2 Environmental GuidesMinor revision for style, grammar, and clarity. No changes to recommendations.
1 - Minor Errata4.8.34.8.3 Graffiti RemovalMinor revision for style, grammar, and clarity. No changes to recommendations.
1 - Minor Errata4.8.44.8.4 LichenMinor revison for style, layout, grammar, and clarity. No changes to recommendations.
1 - Minor Errata4.9.14.9.1 Dissimilar MetalsMinor revision for style, layout, grammar, and clarity. No changes to recommendations.
1 - Minor Errata4.9.44.9.4 Compatibility TableMinor revision for layout, style, grammar, and clarity. No changes to recommendations.
1 - Minor Errata4.10.14.10.1 Unwashed AreasEdit for style, grammar, clarity, and consistency.
1 - Minor Errata4.10.24.10.2 Poultice CorrosionMinor edit for style, grammar, clarity, or consistency. No change to recommendations.
1 - Minor Errata4.10.64.10.6 Capillary ActionMinor edit for style, grammar, clarity, or consistency. No changes to recommendations.
1 - Minor Errata4.114.11 Inert CatchmentMinor edits for style, clarity, consistency, and grammar. No changes to recommendations.
1 - Minor Errata4.124.12 PondingMinor edits for grammar, style, clarity, or consistency. No changes to recommendations.
1 - Minor Errata4.134.13 Pitting CorrosionMinor edit for grammar, clarity, consistency, and style. No changes to recommendations.
1 - Minor Errata4.144.14 Swarf Staining and Cut Edge CorrosionMinor edits for grammar, punctuation, clarity, and consistency. No changes to recommendations.  
1 - Minor Errata4.154.15 ClearancesMinor editing for style, grammar, clarity, and consistency. No changes to recommendations.
1 - Minor Errata4.15.14.15.1 Ground ClearanceMinor edit for style, layout, grammar, clarity, and consistency. No changes to recommendations.
1 - Minor Errata4.15.24.15.2 Site ManagementMinor edit for style, grammar, layout, clarity, and conistency. No changes to recommendations.
1 - Minor Errata4.16.1.14.16.1.1 Metallic CoatingsMinor edit for grammar and punctuation. No changes to recommendations.
2 - Editing and rearrangement4.16.1.64.16.1.6 AM CoatingsRemoved reference to coatings weights and availability in NZ.
1 - Minor Errata4.16.34.16.3 AluminiumMinor edits for grammar, style, punctuation, and consistency. No changes to recommendations.
1 - Minor Errata4.16.44.16.4 ZincMinor edit for style, grammar, and punctuation. No changes to recommendations.
1 - Minor Errata5.75.7 Outlets and DownpipesEdits for clarity and corrected link to Inert Catchment
1 - Minor Errata7.3.27.3.2 Roof Cladding Expansion ProvisionsMinor edit for style, grammar, consistency, or clarity.
4 - Clause Inserted19.119.3 v24.06 June 2024New clause providing details of the updates published on 1 June 2024.