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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 v24.03:Revision-History; 2021-December

19.9 2021 – December 

The following revisions to the NZ Metal Roof and Wall Cladding Code of Practice were published on 1 December 2021.

Summary of Changes in this update:

The rest of this update comprises minor edits and fixes.

19.9A Revision Detail - 2021 - December

CategoryClause Number (at time of update)Clause (As of current publication)Details
3 - Substantial change to recommendation3.17.13.11.1.1 Corrugated Steel – 0.40Drawing edited to change C2 recommendation to stay below Very High.
3 - Substantial change to recommendation3.17.23.11.1.2 Corrugated Steel – 0.55Changed recommendation for C2, to only be used below Very High Wind Zones.
3 - Substantial change to recommendation4.10.34.10.3 Solar Collectors and Other Roof Mounted StructuresClause has been completely revised.
3 - Substantial change to recommendation8.88.9 Compression TimberChanged recommended minimum moisture content to 12% following advice from Scion .
3 - Substantial change to recommendation12.112.1 Roof NoiseThis clause has been substatially revised. Some-subsections have been promoted to headings and some had been deleted a part of the revision.
4 - Clause Inserted 12.1.1 Wind NoiseNew clause, raised and revised from former sub-sub clause of Roof Noise.
4 - Clause Inserted 12.1.2 Precipitation NoiseNewly created clause from the revised Roof Noise.
4 - Clause Inserted 12.1.3 Thermal NoiseNew clause, information elevated from the revised Roof Noise.
4 - Clause Inserted 19.9 2021 – DecemberRevision message for the 1 December 2021 Update.
2 - Editing and rearrangement11 IntroductionUpdate Revisions Message
2 - Editing and rearrangement5.3.75.4.7 Gutter Capacity CalculatorAll calculators now require input of both 50 year and 10 year ARI.
2 - Editing and rearrangement5.4.75.5.7 Valley Capacity CalculatorAll calculators now require input of both 50 year and 10 year ARI.
2 - Editing and rearrangement5.6.35.7.3 Downpipe Capacity CalculatorAll calculators now require input of both 50 year and 10 year ARI.
2 - Editing and rearrangement5.7.15.8.1 Maximum Area Above Spreader CalculatorAll calculators now require input of both 50 year and 10 year ARI.
2 - Editing and rearrangement7.1.47.1.4 Maximum Run CalculatorAll calculators now require input of both 50 year and 10 year ARI.
2 - Editing and rearrangement9.4.49.4.4 Maximum Area Above Penetration CalculatorAll calculators now require input of both 50 year and 10 year ARI.
1 - Minor Errata1.31.3 Standards and Related DocumentsFixed column spacing.
1 - Minor Errata2.12.1 DefinitionsClarified definitions for tray, trough, standing seam, and secret fixed profiles.
1 - Minor Errata3.6.23.7.4 Roof TrafficChanged "trademan" to trades people for gender neutrality.
1 - Minor Errata3.183.10.1 G550 Steel Roof Fastening Pattern TablesFixed grammar for consistency. Fixed drawings to show C2 fastening pattern.
2 - Editing and rearrangement4.6.24.6.2 Environmental GuidesEnvrinmental guides redone for improved display on all browers.
1 - Minor Errata15.115.1 Curved RoofsGrammar fix.
1 - Minor Errata16.816.8 Overpaintingslight formatting change for improved reading.