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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; 2020-June

2020 – June

19.18 2020 – June

The following updates to the NZ Metal Roof and Wall Cladding Code Practice (COP), are effective 1 June 2020.

New clauses:

In this update, we included new clauses concerning 17.2 MRM Fastener Performance Requirements and Testing and 17.3 MRM Soft Edge Standard.
We updated 3.9 Fastener Requirements and Overhangs to include 3.11.2 Aluminium Cladding Wind Load Span Graphs.
We added a new table 5.3.3 Minimum Freeboard Values to 5.3 Roof Drainage Design and implemented interface refinements to 5.4.7 Gutter Capacity Calculator.

The rest of this update consists of minor improvements, such as tidying up drawings and edits for clarity and grammar.

19.18A Revision Detail - 2020 - June

Category	Clause Number (at time of update)	Clause (As of current publication)	Details
2 - Editing and rearrangement	1	1 Introduction	Update Revisions Message
2 - Editing and rearrangement	3.16.4	3.9.3 Fastener Patterns	Fastener pattern illustrations updated for clarity - no change to intent.
2 - Editing and rearrangement	3.16.5	3.11.1 Steel Cladding Wind Load Span Graphs	Clause renamed.
2 - Editing and rearrangement	3.16.5.1	3.11.1.1 Corrugated Steel – 0.40	Clause renamed and Fastener pattern illustrations updated for clarity - no change to intent.
2 - Editing and rearrangement	3.16.5.3	3.11.1.2 Corrugated Steel – 0.55	Clause renamed and Fastener pattern illustrations updated for clarity - no change to intent.
2 - Editing and rearrangement	3.16.5.2	3.11.1.3 Trapezoidal Five Rib Steel – 0.40	Clause renamed and Fastener pattern illustrations updated for clarity - no change to intent.
2 - Editing and rearrangement	3.16.5.4	3.11.1.4 Trapezoidal Five Rib Steel – 0.55	Clause renamed and Fastener pattern illustrations updated for clarity - no change to intent.
2 - Editing and rearrangement	3.16.5.5	3.11.1.5 Trapezoidal Six Rib Steel – 0.40	Clause renamed and Fastener pattern illustrations updated for clarity - no change to intent.
2 - Editing and rearrangement	3.16.5.6	3.11.1.6 Trapezoidal Six Rib Steel – 0.55	Clause renamed and Fastener pattern illustrations updated for clarity - no change to intent.
4 - Clause Inserted		3.11.2 Aluminium Cladding Wind Load Span Graphs	New clause.
4 - Clause Inserted		3.11.2.1 Corrugated Aluminium – 0.70	New Clause for Aluminium Cladding Wind Load Span Graphs.
4 - Clause Inserted		3.11.2.1 Corrugated Aluminium – 0.90	New Clause for Aluminium Cladding Wind Load Span Graphs.
4 - Clause Inserted		3.11.2.3 Trapezoidal Five Rib Aluminium – 0.70	New Clause for Aluminium Cladding Wind Load Span Graphs.
4 - Clause Inserted		3.11.2.2 Trapezoidal Five Rib Aluminium – 0.90	New Clause for Aluminium Cladding Wind Load Span Graphs.
3 - Substantial change to recommendation	5.6.3	5.3.2 Rainfall Intensity	Clause had been completely revised, with updated Rainfall Intensity Maps at the end of the main Clause, Roof Drainage.
1 - Minor Errata	5.6.3.1	5.3.2.2 Duration	Replaced comparison chart with a simplified one.
2 - Editing and rearrangement	8.3	8.4 Flashing Cover	Added minimum flashing cover values for change of pitch junctions.
4 - Clause Inserted		17 Testing and MRM Standards	New clause.
2 - Editing and rearrangement	17	17.1 Metal Cladding Testing	Clause renamed.
1 - Minor Errata	17.5.1	17.1.5.1 Allowance for Variation	Fixed "overall" to "over all"
4 - Clause Inserted		17.2 MRM Fastener Performance Requirements and Testing	New clause.
4 - Clause Inserted		17.2.1 Requirements for Fastener Testing	New clause.
4 - Clause Inserted		17.2.2 Test Panel Requirements	New Clause.
4 - Clause Inserted		17.2.2.1 Test Location	New Clause.
4 - Clause Inserted		17.2.2.2 Site Orientation	New Clause.
4 - Clause Inserted		17.2.2.3 Preparation of Test Panel	New Clause.
4 - Clause Inserted		17.2.3 Fastener Performance Testing	New Clause.
4 - Clause Inserted		17.2.3.1 Site Testing	New clause.
4 - Clause Inserted		17.2.3.2 Field Performance Validation	New clause.
4 - Clause Inserted		17.2.3.3 Accelerated Testing	New clause.
4 - Clause Inserted		17.2.3.4 Fastener Shanks	New clause.
4 - Clause Inserted		17.2.3.5 Sealing Washer Conductivity	New clause.
4 - Clause Inserted		17.2.4 Appearance	New clause.
4 - Clause Inserted		17.2.5 Weatherproofing	New Clause.
4 - Clause Inserted		17.2.6 Fastener Performance Test Report	New clause.
4 - Clause Inserted		17.3 MRM Soft Edge Standard	New clause.
4 - Clause Inserted		17.3.1 Soft Edge Product Techincal Statement Requirements	New clause.
4 - Clause Inserted		19.18 2020 – June	New clause. Revision detail.
0 - Clause Removed	5.5	Gutters	The clause had been removed. Gutters are now discussed in more detail in a separate clause for each type, under the main clause Types of Gutter.