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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.


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:Introduction; Standards-And-Related-Documents

1.3 Standards and Related Documents 


NZ 22952017Pliable, permeable building underlays. (either NZS 2295 2017 or NZS 2295 Amendment 1 2017)
NZS 36022003Timber and wood based products for use in building.
NZS 36031993Amendment 4 2005 Timber Structures Standard.
NZS 36042011Timber Framed Buildings.
AS/NZS 1170.02002Amendment 5 2011 Structural design actions. General Principles. Commentary to Parts 0, 1 and 2.
AS/NZS 1170.12002Amendment 2 2009 Structural design actions. Permanent, imposed and other actions.
AS/NZS 1170.22011Amendment 4 2016. Structural design actions. Wind Actions.
AS/NZS 1170.32013Amendment 1 2007 Structural design actions. Snow and ice actions
AS 1562.11992Design and Installation of sheet roof and wall cladding – Part 1 Metal
AS 1562.32006Design and Installation of sheet roof and wall cladding – Part 3 Plastic (was AS/NZS 1562.3 1996)
AS/NZS 17341997Aluminium and aluminium alloys - Flat sheet, coiled sheet and plate
AS/NZS 27282013Prefinished/prepainted sheet metal products for interior/exterior building applications—Performance requirements
AS/NZS 42571994/97Plastic roof and wall cladding materials. Parts 0-9 Methods of Test.
AS/NZS 43892015Roof Safety Mesh.
AS/NZS 46002005Amendment 1 2010. Cold-formed Steel Structures.
AS 13912007(R2017) Metallic materials - Tensile testing at ambient temperature
AS 13972012Continuous hot-dip metallic coated steel sheet and strip - Coatings of zinc and zinc alloyed with aluminium and magnesium
AS 3566.120021. General requirements and mechanical properties
AS 3566.220022. Corrosion resistance requirements. (Withdrawn)
AS 42562006Plastic roof and wall cladding materials. (Now AS only previously AS/NZS 4256 1994). Parts 1-5. Plastic materials.
BS 14701987Specification for wrought aluminium and aluminium alloys for general engineering purposes. (Replaced by 9 EN Standards) See AS 1734
BS 28701980Specification for rolled copper and copper alloys. (Replaced by EN standards)
BS EN 9881987and BS EN 1179 2003 Specification for zinc alloy sheet and strip
ISO 92232012Corrosion of metals and alloys. Corrosivity of atmospheres - Classification.
ISO 92242012Corrosion of metals and alloys. Corrosivity of atmospheres - Guiding values for the corrosion categories.
ISO 92252012Corrosion of metals and alloys -- Corrosivity of atmospheres -- Measurement of environmental parameters affecting corosivity of sites
ISO 92262012Corrosion of metals and alloys -- Corrosivity of atmospheres -- Determination of corrosion rate of standard specimens
AS/NZS 3500.32015Stormwater drainage
AS/NZS 2179.12014Metal shape or sheet rainwater goods, and metal accessories and fasteners
AS 21801986Metal rainwater goods - Selection and installation
HB 1141998Guidelines for design of eaves and box gutters
AS 43122008Atmospheric corrosivity zones in Australia
HB 392015Installation code for metal roofing and wall cladding
AS/NZS 23122002Guide to the protection of structural steel against atmospheric corrosion by the use of protective coatings
AS 4040.01998Methods of testing sheet roof and wall cladding Introduction, list of methods and general requirements
AS 4040.11998Methods of testing sheet roof and wall cladding Resistance to concentrated loads
AS 4040.21998Methods of testing sheet roof and wall cladding Resistance to wind pressures for non-cyclone regions
AS/NZS 4200.12017Pliable building membranes Part 1: Materials
AS 4200.22017Pliable building membranes Part 2: Installation