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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; 2022-June

19.6 2022 – June 

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

Revised clauses:

Clause 15.4 Tray Roofing and all its sub-clauses were comprehensively revised for this update.

Change in recommendation:

The rest of the updates consisted of minor changes, grammar fixes, and minor edits to improve clarity.

19.6A Revision Detail - 2022 - June

CategoryClause Number (at time of update)Clause (As of current publication)Details
3 - Substantial change to recommendation3.23.10.3 Aluminium Fastening Pattern TablesCorrected minimum depth of corrugated aluminium to 17 mm instead of 27 mm. Added H36 to the headings for correct identification and product selection.
3 - Substantial change to recommendation7.1.17.1.1 Minimum Roof Cladding PitchAdded corrugated profiles with a height of more than 35 mm to 7.1.1A Minimum Pitch for Generic Metal Roofing.
3 - Substantial change to recommendation8.38.4 Flashing CoverIncreased recommended cover for 8.4E Barge Flashing Cover — Trapezoidal and Secret Fixed and 8.4G Barge Flashing Cover — Corrugate Category C from 50 mm to 75 mm.
3 - Substantial change to recommendation15.415.4 Tray RoofingThe entire clause 15.4 Tray Roofing, including all sub-clauses, had been revised.
3 - Substantial change to recommendation15.4.315.4.1 Tray Roofing MaterialsThis sub-clause has been entirely revised as part of the revision of the main clause 15.4 Tray Roofing.
4 - Clause Inserted 15.4.2 Tray Roofing ProfilesNew clause, inserted as part of a comprehensive revision of 15.4 Tray Roofing.
4 - Clause Inserted 15.4.5 Tray FixingsNew clause, inserted as part of a comprehensive revision of 15.4 Tray Roofing.
4 - Clause Inserted 15.4.6 Standing Seam End LapsNew clause, added as part of the comprehensive revision of 15.4 Tray Roofing.
4 - Clause Inserted 15.4.7 SarkingNew clause, introduced as part of a comprehensive revision of 15.4 Tray Roofing.
4 - Clause Inserted 15.4.8 Tray VentilationNew clause, introduced during a comprehensive review of 15.4 Tray Roofing.
4 - Clause Inserted 15.4.9 Standing Seam Roofing Wind LoadsNew clause, introduced during comprehensive revision of 15.4 Tray Roofing.
4 - Clause Inserted 15.4.10 Penetrations on Tray RoofingNew clause, introduced during a comprehensive review of 15.4 Tray Roofing.
4 - Clause Inserted 15.4.12 Canning and Purlin CreasingNew clause, introduced as part of a comprehensive revision of 15.4 Tray Roofing.
4 - Clause Inserted 15.4.13 Installing Tray CladdingNew clause, introduced as part of a comprehensive revision of 15.4 Tray Roofing.
4 - Clause Inserted 15.4.13.1 Tray Cladding Set OutNew clause, introduced a during a comprehensive revision of 15.4 Tray Roofing.
4 - Clause Inserted 15.4.13.3 Provision for Expansion — Tray RoofingNew clause, introduced during a comprehensive revision of 15.4 Tray Roofing.
4 - Clause Inserted19.119.6 2022 – JuneRevision message June – 2022.
2 - Editing and rearrangement11 IntroductionUpdate Revisions Message
2 - Editing and rearrangement3.183.10.1 G550 Steel Roof Fastening Pattern TablesEdited table headings for improved readability. Inserted a table explaining wind speed as per NZS 3604.
1 - Minor Errata9.4.2.39.4.2.3 Cricket Back CurbsGrammar fix. Rewrote the last sentence.
1 - Minor Errata17.1.2.2.317.1.2.2.3 Number of SpansClarification.
0 - Clause Removed15.4.1Self-Supporting CladdingClause removed during a comprehensive revision of 15.4 Tray Roofing. The subject is now discussed through various new sub-clauses.
0 - Clause Removed15.4.2Fully Supported Roof And Wall CladdingClause removed during a comprehensive revision of 15.4 Tray Roofing. For information about the subject, see 15.4.7 Sarking.
0 - Clause Removed15.4.2.1TypesClause removed as part of the overall revision of 15.4 Tray Roofing.
0 - Clause Removed15.4.2.2Traditional Architectural Metal PanelsClause removed as part of the overall revision of 15.4 Tray Roofing.
0 - Clause Removed15.4.2.3Long Length Strip Roof CladdingClause removed as part of the overall revision of 15.4 Tray Roofing.
0 - Clause Removed15.4.2.4Types Of JointsClause removed as part of the overall revision of 15.4 Tray Roofing.
0 - Clause Removed15.4.2.5Standing SeamClause removed as part of the overall revision of 15.4 Tray Roofing.
0 - Clause Removed15.4.2.6Angled SeamClause removed as part of the overall revision of 15.4 Tray Roofing.
0 - Clause Removed15.4.2.7Roll CapClause removed as part of the overall revision of 15.4 Tray Roofing.
0 - Clause Removed15.4.2.8Transverse LapsClause removed as part of the overall revision of 15.4 Tray Roofing.
0 - Clause Removed15.4.3.1CopperClause removed as part of the overall revision of 15.4 Tray Roofing. For information about this material, see 4.16.5 Copper.
0 - Clause Removed15.4.3.2ZincClause removed as part of the complete revision of 15.4 Tray Roofing. For information about this material see 4.16.4 Zinc.
0 - Clause Removed15.4.3.3AluminiumClause removed as part of the complete revision of 15.4 Tray Roofing. For information about this material see 4.16.3 Aluminium.
0 - Clause Removed15.4.3.4Stainless SteelClause removed as part of the complete revision of 15.4 Tray Roofing. Information about this material can be found at 4.16.2 Stainless Steel.
0 - Clause Removed15.4.3.5Coated SteelClause removed as part of the revision of 15.4 Tray Roofing, information about this product is still available in 4.16.1 Steel.
0 - Clause Removed15.4.4LoadingsClause removed as part of the overall revision of 15.4 Tray Roofing.
0 - Clause Removed15.4.4.1FixingClause removed as part of the overall revision of 15.4 Tray Roofing.
0 - Clause Removed15.4.4.2SubstrateClause removed as part of the overall revision of 15.4 Tray Roofing.
0 - Clause Removed15.4.4.3FastenersClause removed as part of the overall revision of 15.4 Tray Roofing.
0 - Clause Removed15.4.5UnderlayClause removed during a comprehensive revision of 15.4 Tray Roofing. Information about underlay can be found in 10.11 Underlay.
0 - Clause Removed15.4.6VentilationClause removed during a comprehensive revision of 15.4 Tray Roofing. The subject is now discussed in 15.4.8 Tray Ventilation.
0 - Clause Removed15.4.7DrainageClause removed during a comprehensive revision of 15.4 Tray Roofing. For information about drainage, see 5 Roof Drainage .
0 - Clause Removed15.4.7.1ValleysClause removed as part of the overall revision of 15.4 Tray Roofing.
0 - Clause Removed15.4.8Facade CladdingThis clause was removed during a comprehensive revision of 15.4 Tray Roofing. The subject is now discussed through various other sub-clauses.
0 - Clause Removed15.4.9Edge FinishesThis clause was removed during a comprehensive revision of 15.4 Tray Roofing, please see the new sub-clause 15.4.6 Standing Seam End Laps.
0 - Clause Removed15.4.9.1Ridge And HipClause removed as part of the overall revision of 15.4 Tray Roofing.
0 - Clause Removed15.4.9.2Apron Or AbutmentClause removed as part of the overall revision of 15.4 Tray Roofing.
0 - Clause Removed15.4.9.3Eaves And VergeClause removed as part of the overall revision of 15.4 Tray Roofing.
0 - Clause Removed15.4.9.4PenetrationsClause removed as part of the overall revision of 15.4 Tray Roofing.
0 - Clause Removed15.4.9.5CappingsClause removed as part of the overall revision of 15.4 Tray Roofing.
0 - Clause Removed15.4.10DurabilityClause removed during a comprehensive revision of 15.4 Tray Roofing. For durability issues, see 15.4.10 Durability.
0 - Clause Removed15.4.10.1Patina FormationClause removed as part of the overall revision of 15.4 Tray Roofing.
0 - Clause Removed15.4.10.2Copper PatinationClause removed as part of the overall revision of 15.4 Tray Roofing.
0 - Clause Removed15.4.10.3Zinc PatinationClause removed as part of the overall revision of 15.4 Tray Roofing.