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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 v23.12:Revision-History; 2023-September

19.2 2023 – September 

The following revisions to the NZ Metal Roof and Wall Cladding Code of Practice were published on 1 September 2023.

Versioning and presentation:

  • Beginning with this revision the Code of Practice updates its version number with each update, to make it clear when the current update was published.
    The version numbering uses a year.month pattern: for example this update is v23.09, where 23 indicates the year (2023) and 09 indicates the month (September).
    Refer to 19 Revision History for a log of specific changes in each update.
  • An overall upgrade to styling for improved typeface readability and better contrast in headings.
  • Additionally there are new "Quick Actions" on the COP Home page for reference to updates and interactive tools, and the registration process has been streamlined.

Substantial change to recommendations:

Editing and rearrangement:

The rest of the updates consisted of minor corrections and edits.

19.2A Revision Detail - 2023 - September

CategoryClause Number (prior to update)Clause (As of current publication)Details
2 - Editing and rearrangement11 IntroductionUpdated Revisions Message
2 - Editing and rearrangement1.11.1 Disclaimer and CopyrightRemoved copy explaining the update-policy and created a new subclause for those explanations.
4 - Clause Inserted 1.1.1 Code of Practice Update-PolicyOutline the update policy, new Version numbering scheme, and process for requesting archival content
2 - Editing and rearrangement2.12.1 DefinitionsAdded definition for Reglet flashing.
4 - Clause Inserted 3.11 Wind Load/Span Graphs – Designs to AS/NZS1170New clause to group 3.11.1 Steel Cladding Wind Load Span Graphs and 3.11.2 Aluminium Cladding Wind Load Span Graphs for designs to AS/NZS 1170.
2 - Editing and rearrangement33 StructureRevision of the introductory clause to clarify uses of 3.10 Fastening Pattern Tables – Designs to NZS 3604 and3.11 Wind Load/Span Graphs – Designs to AS/NZS1170.
1 - Minor Errata3.2.13.2.1 AS/AZS 1170.2:2011Fixed typo: amendments. Completed the last sentence and formatted the link to 3.7 Modes of Failure properly.
1 - Minor Errata3.6.2.13.6.2.1 Wind LoadResized photographs so they display the same.
1 - Minor Errata3.6.2.23.6.2.2 Snow LoadsGrammatical fix for clarity.
1 - Minor Errata3.7.23.7.2 DeflectionFixed typo: distributed and roofing.
2 - Editing and rearrangement3.93.9 Fastener Requirements and OverhangsClause has been renamed.
4 - Clause Inserted 3.10 Fastening Pattern Tables – Designs to NZS 3604New clause to group 3.10.1 G550 Steel Roof Fastening Pattern Tables and 3.10.3 Aluminium Fastening Pattern Tables for NZS3604-designs.
3 - Substantial change to recommendation4.9.44.9.4 Compatibility TableCorrection to "use with caution" for contact between concrete and steel. Removed brand names in favour of generic descriptive terms.
4 - Clause Inserted4.15.14.15.1 Ground ClearanceNew clause under 4.15 Clearances
3 - Substantial change to recommendation5.5.75.5.7 Valley Capacity CalculatorEnabled valley calculations for roofs at pitches below 3° - enforces a minimum freeboard of 30mm
3 - Substantial change to recommendation5.6.25.6.2 SumpsAdded recommendation for internal sumps to be sealed against the sides and sole of the gutter. Some typo fixes.
1 - Minor Errata6.26.2 ComplianceFixed a missing link to: 7 External Moisture Roofing, 8 External Moisture Flashings, and 9 External Moisture Penetrations.
2 - Editing and rearrangement8.28.2 Flashing DesignRevised 8.2A Notched Flashing illustration to recommend a screw fastener to the purlin in preference to a rivet.
2 - Editing and rearrangement8.2.18.2.1 Flashing EdgesRemoved recommendation to provide longitudinal flashings with an anti-capillary gap, as this is impractical.
4 - Clause Inserted 8.3 Metal Fascias and FacadesA new clause providing guidance for purpose-made Metal Fascias and Facades.
2 - Editing and rearrangement8.4.48.5.5 Apron FlashingsCorrected name for 8.5.5H Parapet — Reglet Flashing, Chase Cut and 8.5.5I Parapet — Reglet Flashing, Face Fixed.
2 - Editing and rearrangement9.4.2.69.4.2.6 Penetration Flashings on Trapezoidal ProfilesClarifying text for fixing under-soaker flashing added to 9.4.2.6B Level Under-Soaker: Trapezoidal,
1 - Minor Errata1212 Fitness For PurposeFixed typo: Addition
1 - Minor Errata13.313.3 Working on RoofsEdited the caption under 13.3A Working on Roofs Safety Systems.
1 - Minor Errata14.314.3 Accepting DeliveryAdded clarifying statement to contact the supplier when the condition of the product is in doubt.
1 - Minor Errata14.13.114.13.1 NailsPhoto of Nail Pull-Out rotated.
3 - Substantial change to recommendation14.19.314.19.3 Correctly Installed GuttersChanged recommendation for gutter drainage to be more consistent with MBIE tolerances.
1 - Minor Errata15.1.115.1.7 Spring CurvingUpdated reference to the tables in this clause.
1 - Minor Errata15.1.615.1.6 Concave RoofsRemoved reference to a redundant table. Some grammar fixes.
1 - Minor Errata15.1.915.1.11 Crimp CurvingFixed a broken link to 16.8 Overpainting.
2 - Editing and rearrangement15.4.815.4.9 Standing Seam Roofing Wind LoadsRenamed table, it is now called: Generic Standing Seam Clip Spacing and inserted Medium Wind Zone.
1 - Minor Errata15.4.12.415.4.13.4 Finishing at Ridges and Eaves of Tray RoofingTypo fix.
1 - Minor Errata1616 Maintenance Some editing for accuracy.
4 - Clause Inserted 16.1 Maintenance ComplianceNew clause inserted.
0 - Clause Removed16.1Improved DurabilityClause removed during the over-all revision of 16 Maintenance .
0 - Clause Removed16.2Normal MaintenanceThis clause was removed during the over-all revision of 16 Maintenance
4 - Clause Inserted 16.3 Reactive MaintenanceNew clause created during the over-all revision of 16 Maintenance .
3 - Substantial change to recommendation16.316.4 Scheduled MaintenanceThe clause was revised as part of the overall revision of 16 Maintenance .
3 - Substantial change to recommendation16.416.5 Preventative MaintenanceThis clause was revised during the overall revision of 16 Maintenance .
3 - Substantial change to recommendation16.516.6 Special MaintenanceThis clause was revised during the overall revision of 16 Maintenance .
3 - Substantial change to recommendation16.616.2 InspectionClause revised as part of the over-all revision of 16 Maintenance .
3 - Substantial change to recommendation16.716.7 WashingThis clause was revised during the overall revision of 16 Maintenance .
3 - Substantial change to recommendation16.7.116.7.1 Lichen And MouldTHis clause was revised during the overall revision of 16 Maintenance .
2 - Editing and rearrangement16.7.216.7.2 GraffitiThis clause was revised during the overall revision of 16 Maintenance .
3 - Substantial change to recommendation16.816.8 OverpaintingThis clause was revised during the overall revsion of 16 Maintenance .
4 - Clause Inserted 16.8.1 Preparation for OverpaintingNew clause created during the overall revision of 16.8 Overpainting.
3 - Substantial change to recommendation16.8.116.8.3 Unpainted CladdingThis clause has been revised during the overall revision of 16 Maintenance .
2 - Editing and rearrangement16.8.216.8.4 Weathered Pre-Painted CladdingThis clause was revised during the overall revision of 16 Maintenance .
2 - Editing and rearrangement16.8.316.8.1.1 White CorrosionThis clause has been revised during the overall revision of 16 Maintenance .
2 - Editing and rearrangement16.8.416.8.1.2 Red CorrosionThis clause was revised during the overall revision of 16 Maintenance .
4 - Clause Inserted 16.8.5 Unweathered Pre-Painted CladdingNew clause created during the overall revision of 16 Maintenance .
3 - Substantial change to recommendation16.8.516.8.2 ApplicationThis clause has been renamed and completely revised during the overall revision of 16 Maintenance , previously independent clauses have also been incorporated. They are: Brush Application, Roller Application, Spray Application 
0 - Clause Removed16.8.6Brush ApplicationThis clause has been removed during the overall revison of 16 Maintenance . Brush Application is now discussed in 16.8.2 Application.
0 - Clause Removed16.8.7Roller ApplicationThis clause has been removed during the overall revison of 16 Maintenance . Roller Application is now discussed in 16.8.2 Application.
0 - Clause Removed16.8.8Spray ApplicationThis clause has been removed during the overall revison of 16 Maintenance . Spray Application is now discussed in 16.8.2 Application.
0 - Clause Removed16.9Material SelectionThis clause was removed during an overall revision of 16 Maintenance .
0 - Clause Removed16.9.1ResidentialThis clause was removed during an overall revision of 16 Maintenance .
0 - Clause Removed16.9.2CommercialThis clause was removed during an overall revision of 16 Maintenance .
0 - Clause Removed16.9.3Responsibility and LiabilityThis clause was removed during an overall revision of 16 Maintenance .
0 - Clause Removed16.9.4Special Environments And ExclusionsThis clause was removed during an overall revision of 16 Maintenance .
0 - Clause Removed16.11StorageThis clause was removed during an overall revision of 16 Maintenance .  Storage is dealt with through various clauses under 14 Installation.
2 - Editing and rearrangement18.218.2 Pitch & Rise CalculatorRenamed from "Roof Pitch Tangent" to "Pitch & Rise Calculator" for clarity.
2 - Editing and rearrangement18.518.5 Geometry And MeasurementRenamed from "Geometry And Mensuration" to "Geometry And Measurement".
4 - Clause Inserted 19.2 2023 – SeptemberNew clause listing revisions for September 2023.